I have written quite a bit on the differences between Lasik and PRK (Primer on PRK vs Lasik and Lasik vs PRK: What the Lasik Doctor Doesn’t Tell You – Short story: Run screaming from Lasik, it’s dodgy as hell, the very definition of a ‘quick-fix’), and I’ve written about my own PRK experiences (My Laser Eye Surgery, Part I: PRK Pre-Op Preparation, My Laser Eye Surgery, Part II: The PRK Operation, My Laser Eye Surgery, Part III: PRK Post-Op Recovery), but I haven’t yet spoken much about my own side-effects from my laser eye surgery.

Six-plus years after surgery, I’m still incredibly happy with both the recovery and with the results (vision I think is still better than 20/20, but as I age it’s naturally deteriorating). I have suffered (and still ‘suffer’) one side-effect: haloing. Halos can occur regardless of whether you’ve gotten Lasik, which cuts a flap in the cornea (never get Lasik!), or PRK/Epi-Lasik/Lasek (note the e in Lasek), which do not cut flaps in the cornea.

What is Haloing?

Haloing is an effect where your pupil opens wider than your corrected zone on your cornea (effectively a lens carved into the cornea itself). The image hitting your eye is simultaneously well-corrected and uncorrected. This results in an faint (typically less uncorrected light is getting through) overlapping blur, often with a starburst-like effect.

For me, before surgery, I would look at lights in the city night sky and see some form of haloing even with my contacts and glasses. I researched what it could look like and compared with what I was already getting. Hopefully the reader can make the same decision process.

I knew going into my surgery that my absolute widest pupil diameter was about 8-8.5mm. I measured my own in a *completely* dark room using a camera with a flash that would bounce off the ceiling and capture the pupils at the instant before they reacted to the flash. My laser doc measured my pupils in a semi-dark room and got about 6.5mm.

My highly scientific pupillary measurement process.

I knew that the system’s true correction zone (ignore any taper zone, that’s worthless, as I’ve written about in my Pre-Op Preparation article) was about 6-6.5mm, so I knew that I was going to be susceptible to haloing under very dark conditions. And I am, and will be forever. Unless I get my eyes done again in later years after my vision naturally deteriorates (and assuming these future machines have wider treatment zones).

In my case, I have say 6-6.5mm of great corrected vision, but a donut-shape of another 2mm of uncorrected vision. So in very dark conditions (and only in very dark conditions) I will get 70-80% of the light entering my eye and hitting my retina being corrected perfectly, but overlapping that, 20-30% of the light will be blurry, virtually the same blurriness as it was before my surgery.

This results in excellent vision of objects, with a faint after-image. But only when haloing will occur.

When Does Haloing Occur?

In practice, I only notice it when there is a rather bright object in a very dark setting. When the setting is very dark (driving at night in the country), but the object is not bright enough (pretty much everything except headlights and retroreflector cat-eyes on signs/road/etc), the halo is too faint to see, it’s below my visual acuity. And when the setting is bright enough (driving in the city), the ambient light from orange streetlights is more than enough to contract my pupil to 6-6.5mm (still quite wide), and all the light hitting my retina is corrected, so there are no halos.

I really only notice it in the countryside. Very bright stars have halos, but fainter ones do not (their halos are too faint to detect). Cat-eyes on the side of the road and reflective signs in the distance (small size) have halos, but large size signs or the moon do not (maybe because their size and brightness contracts my pupils?).

And I can make all the halos go away if I turn on the map-light in my car. It’s a fairly dim light, shining only on the dark console between the seats, but that’s just enough ambient light to contract my pupils. I can actually play with it. A distant road sign will have a halo, and when I increase/decrease the brightness in the car just enough, I can watch the halo shrink/increase as my pupil contracts/dilates.

Anyway, it’s interesting. But not really disturbing. I’d prefer not to have it, but I haven’t actually changed my behaviour any way. I don’t drive with any lights on in the car cabin (even though the light is still quite faint, just enough to have my pupils go from Extremely Wide to Very Wide). It simply never bothers me enough to bother about it. It’s kind of interesting though.

How Likely are Halos

From what I understand, the best laser systems as of this writing (2017) offer a true treatment zone with correction (ignoring taper zones) of about 6-6.5mm. And since typical human pupils can expand to around 8mm in very dark conditions, some degree of haloing is fairly likely to occur in most people who undergo laser eye surgery. However, that does not mean that all haloing is considered equal, or that each person will experience halos under the same lighting conditions. Slight changes in pupillary response can dramatically increase the frequency of haloing.

Should I Worry about Halos?

Absolutely. If you think about it, how your pupils react to different lighting conditions, and how bad your prescription was before surgery will both have a big effect on your haloing.

If your pupils go Extremely Wide (beyond the treatment zone, ignoring taper, etc) under relatively lighter ambient lighting situations (say driving at night in the city), then you’re going to experience haloing much more frequently. If I saw halos on every bright object (remember only the bright objects have enough light for their 20-30% halo to even register) in the city, then I may not be happy about that. Some folks who undergo laser eye surgery, especially on machines that have smaller true treatment zones (broken record: taper zones mean nothing, ignore them), will experience halos even under fairly bright ambient lighting conditions, like city driving at night.

There’s a big difference there. If you only experience haloing when it’s very dark, you’re going to experience very few cases where there is a bright enough light to halo that triggers one. However, if you experience haloing (if your pupils expand beyond the treatment zone) when it’s not completely dark, like in a city, then there are going to be LOTS of bright lights creating that ambient light, and you’re going to experience a lot of haloing.

Uncorrected vision before surgery will also affect how large the halos are. If, before surgery, the light causing the halo would have been only slightly enlarged from blurring, the faint haloing will only be as large as that after-surgery (under halo lighting conditions). But if your vision was so poor that oncoming headlights would have been blurred out to the size covering half your vision, then that diffusion of the light through your uncorrected cornea will still enter the eye. It will likely be fainter, but could be very large.

Summary

It’s essential to know what your true treatment zone (the fully-corrected, non-tapered treatment zone) will be. And it’s important to know how wide your pupils get in dark and semi-dark conditions.

I knew before my surgery that my eyes would expand wider than my treatment zone under very dark conditions, but that my pupils were not wider than the treatment zone under moderately dark conditions. I was okay with this, understanding when I would see halos and when I would not.

To be honest, as with all aspects of laser eye surgery I discuss on here, I’d prefer if the surgeon gave all the information on the topic that a prospective patient would need to make an informed decision. I understand that many prefer not to know all the nitty-gritty details, and would prefer to go into the surgery with their eyes closed (ha!). That’s obviously not me. And I’m assuming that’s not you.

That said, I understand why the doctors typically measure your pupil in a ‘mostly dark’ room. That more closely simulates the environments you’d be most annoyed if you had haloing. It’s not often that we are in extremely dark settings that have very bright lights. Driving at night in the dark countryside is one of them. And even then, at least for me, it’s more of a science experiment than an inconvenience.

Of course each prospective patient is going to have to ask their own questions, get their own answers from their doctors, and come to their own decision about haloing. About all aspects of the surgery.

Good luck, and keep me posted on your journey!

Continued Reading

Here are my posts on PRK and laser eye surgery, continue reading or, feel free to join the discussion in the comments below!

Laser Eye Surgery Primer: Lasik vs PRK
Lasik vs PRK: What the Lasik Doctor Doesn’t Tell You
My Laser Eye Surgery, Part I: PRK Pre-Op Preparation
My Laser Eye Surgery, Part II: The PRK Operation
My Laser Eye Surgery, Part III: PRK Post-Op Recovery
Halos: A Likely Complication of PRK or Lasik (You are Here)
    

The post Halos: A Likely Complication of PRK or Lasik appeared first on is this your homework?.

In July of 2011, I had PRK laser eye surgery done. Shortly before, I wrote up a Primer on PRK vs Lasik that the reader may find interesting (TL;DR: Lasik is a dodgy quick-fix, avoid it, stick with PRK). Since then I expanded on the differences between PRK and Lasik, which hopefully provides the reader with all the questions they should be asking their laser eye surgeon: Lasik vs PRK: What the Lasik Doctor Doesn’t Tell You.

Before I went into the surgery, I did a great deal of research and found a dizzying array of variables that the prospective patient should take into account before choosing whether to have the surgery and where to have it performed. Resulting from this research I detailed the critically important questions that need to be asked before going under the laser: My Laser Eye Surgery, Part I: PRK Pre-Op Preparation. In a subsequent article, I described the PRK procedure itself: My Laser Eye Surgery, Part II: The PRK Operation.

Here, at long last is my account of my Post-PRK recovery. I’d written some of this in the months following my surgery for a friend who was considering the procedure, but for unknown reasons never posted it here. Well, here it is, some six-plus years later. And yes, I’m still extremely happy with my PRK experience. I would do it again in a heartbeat (though I’d look into the new epithelial-flap (not corneal-flap like Lasik!) methods like Lasek (note the e) or Epi-Lasik.

Day 1

No pain, just a little dryness. Feels like you’ve had non-breathable contacts in overnight (which you have). Overall, the eyes were scritchy, but I was happy playing Ray Charles in the blacked-out apartment. I listened to a few audio books, took lots of drops constantly (never did the pain ones as I mentioned), and chewed gum to try to get rid of the awful taste of the antibiotic drops as they drip down the back of your throat (you’ll love that bit!). Got driven by my friend to my 1-day follow up and everything was looking good. It was a very bright trip, but not as bad as immediately post-op. I took another half sleeping pill that night, not so much because I was uncomfortable, but because I didn’t do anything all day and wasn’t really tired. I wanted to make sure I got a ton of sleep though, as that helps the healing process.

Day 2

No pain but slightly more discomfort, you’re now at 48h wearing the same non-breathable bandage contact lens. I didn’t take any drugs (not even ibuprofen). Boredom was the worst part, but I entertained myself with frequent trips to the bathroom to pee from all the water I was drinking, by eating, with more audiobooks, and by listening to a couple DVDs with my eyes closed. I used my computer a tiny bit, but it was really bright, I couldn’t see very well (huge magnification required), and the strain wasn’t super good for me. That night I took another half of a sleeping pill for the same reasons.

Day 3

This is the only day that was bad. My eyes were very dry, I’d now been wearing the same non-breathable contacts for 72h and my eyes were really dry and really scratchy, even with the constant lubrication of the eye drops. This is where the nickel really dropped on the preservatives in the eye drops, as my eyes were really dry and scratchy and they were no longer providing much relief at all, almost making it worse. I took a T3 in the morning and it was a lot better. I went to my 3-day follow-up. I took the skytrain and bus over there. My light sensitivity was not crazy bad, but I did have two pair of sunglasses on and a hat. My progress was going well, they lowered the frequency of the steroid drops on one eye, and kept the other at the same level. Best thing was that they replaced the bandage contact lenses with a new pair. Hallelujah! That felt a hundred times better. With the new pair, the pain and discomfort didn’t make its way past the T3s. I kept on the T3s every 4h or so, when the pain would come back (ever had super dry eyes? It’s like that), and then my wife came home with the new preservative free drops. That made a huge difference, and I was finally over the worst of it that evening. I took another half of a sleeping pill that night, just to make sure I got a good night’s sleep through the discomfort, but I did sleep well.

Preservative-free drops are absolutely essential.

Day 4

This day was easy. You’re back to boredom though. Your eyes are a bit dried out and scratchy (mostly due to the new bandage contact), but the new drops do the trick. I may or may not have taken a T3 that morning, but I don’t think I did. I started to get pretty stir-crazy this day, but I kept entertained by going from couch to bathroom all day for water, urination, and drops. I snuck a few minutes on my computer to see how the world was doing and post something pithy and only mildly self-pitying on my social media, but I still couldn’t really bear it much. To deal with the boredom, my wife and I went for a walk that night when it got dark, and it was glorious to get out of the house. I did without the sleeping pill.

Day 5

By now, your eyes are back to drier than a nun’s… well, they’re dry, and scratchy. I couldn’t really detect any traces of the ‘healing pain’ and ‘rawness’ I’d felt over the past few days, so I was pretty sure all the discomfort was from the 48h of wearing the bloody contact lens. I went to my 5-day post op appointment (again by myself on Skytrain and bus), and man did it feel great to get out of the house again. The first part of the checkup was the removal of the accursed bandage lenses, and immediately, I felt like a million bucks. All the pain and discomfort vanished. The checkup went well and the doc stopped the drops in one eye, and told me to do once a day on the other eye for two more days. The photosensitivity was pretty much under control by that point, and I took the tinfoil down either that afternoon or the next morning.

Week 2

No pain, no discomfort. I used the no-preservative eye drops when I’d feel a bit of dryness, but this was pretty infrequent. I kept a little 1ml blister drop back in my pocket at all times, but only really used them when I was staring unblinking at my computer or walking around outside. By the end of week two, I was still carrying them, but rarely used them.

During all this time though, actually right from Day 0, my eyesight wasn’t very good. It was much better than I was without my contacts, but it was still not good enough to pick out really any details on anything, no matter how close or how far. The vision wasn’t near-sighted, it was as if you were trying to look through a slightly blurred lens. It’s hard to describe, but it’s as if your focus capability is great, but your resolving detail wasn’t there. I could see things equally poorly at 1m and at 10km.

Over this first two weeks, as I’d anticipated through my reading, the vision ‘cured’ up gradually. After about a week and a half, the detail was coming along pretty well, but by then I was experiencing slight double-vision, “ghosts” as they’re called. This is where, due to the swelling and healing of the epithelium, there is a slight, faded double image that is slightly offset from the main image. What made it challenging was that the ghost would be offset in different directions for each eye. So, there’d be a faint double image at 2 o’clock on one eye, and another faint double-image at, say 6′oclock on the other eye. The result: treble-vision.

Again, this was expected, but it made the detail in the world all but impossible to see. I could walk around fine, see shapes, signs, etc, way better than I could before surgery without glasses, but it was hard to make out details. As a result, I was walking around in a bubble of awareness that was just large enough to keep me from bumping into people and tripping over things. My world felt small, so the cabin-fever effect was still there from the 5 days of being a shut-in. I actually played a game of ultimate on Day 7 post op. (cleared with the doc and wearing safety sunglasses of course). I couldn’t really see the disc and was pretty ineffective, so I stayed on the sideline mostly. Still, I got out of the house.

Generally the vision and ghosting would be pretty good in the morning, and as the eyes would dry out more through the course of the day, it would get worse. From day to day, it would improve, usually better in the morning than it had been the day before, but some days it would slide backwards. Each eye was on its own schedule. I expected this, complete with setbacks, but there was some frustration involved as you’d wake up and think you’re done with the visual artifacts, only for them to come back by the end of the day.

Throughout this week, I was on the computer a fair bit, but it was a bit of a pain, it still required giant font sizes, but less and less so over the course of the first 2 weeks. I probably could have, but I didn’t feel comfortable driving by the end of Week 2.

Week 3

I played another game of ultimate at the start of Week 3 on Day 14. By now I could see quite well, but still had the ghosting fairly noticeable. I had optimistically hoped I’d be back to normal 2.5 weeks after the surgery, for a big ultimate tournament, but I still had the ghosting fairly strong. I could mitigate this somewhat with the eye-drops, but not entirely and only for a little bit. I took a couple discs off the face that weekend, but I had fun. I had optimistically hoped that I’d be back on my ice-skates playing goal by then, but that would not have worked.

Right around the three week mark, as if a switch was thrown, my ghosting disappeared. My vision felt super-human. Whether it was three weeks of not being able to see or whether it was actually better than with my contacts previously, I felt like I could see details that I could never see before. I had set up a few benchmarks before the surgery, little eye tests I could give my self, and it looked like I was indeed better than my pre-op correction ever was. I could see detail on the trees at the top of the North Shore mountains from Downtown, license plates and road signs at greater distances, and the registration marks on the cargo containers at the rail yard across the street.

By now, my computer screen was back to normal size, and I had been driving since the 2.5 week mark. At the end of Week 3, I was forgetting at times that I’d had the surgery done. I wasn’t using any drops any longer, as for the past week or so, they were just to keep the ghosting under control.

Aside: A cure for eye dryness?

Also of note was that my eyes, even when I wouldn’t wear my contacts for a week or so, would always be relatively dry and red. I’d often wake up with little crystalline ‘eye crusties’ and have to rub them away when waking up. Surprisingly, since the surgery, this has disappeared altogether. After the first week, once I stopped wearing my sunglasses all the time, my wife was really surprised at how much whiter my eyes were. The redness that was always there previously was gone. I wondered if this was due to all the drops I was taking as part of the regimen, but it’s held out all this time. The dryness of my eyes is improved across the board. I woke up maybe twice with dry eyes in the first few weeks, but that was a more acute, painful dryness (soothed by the lubricating drops) than the general dry-tiredness that I’d usually wake up to. Other than those two occasions, I haven’t really noticed my eyes being dry at all in the 6+ years since the surgery. Only if I’m being very bad to them, staying up late staring at a computer screen, but even then, much less severe than pre-surgery. I had heard that this isn’t altogether uncommon in PRK surgeries, for it to help cure dry eyes, but I simply hadn’t really thought of myself as somebody who even had dry eyes before surgery. There you go.

Of course, Lasik can have serious complications with Dry Eye (to be fair there are very rare cases with PRK too). This isn’t your typical eye dryness that I experienced before surgery when I’d wear non-breahtable contacts overnight. I experienced this painful dry-eye in the days following the surgery. It’s extremely painful. It’s a lot more frequent with Lasik (PRK too in some extremely rare cases), because Lasik cuts that flap into the cornea, and when doing so, there’s a chance of cutting a nerve that helps keep your eyes hydrated. One so-called ‘solution’ to this with Lasik is surgically implanting plugs into your tear drainage ducts. This helps keep your eyes flooded more. I don’t know about you, but to me that doesn’t seem like much of a fix!

Weeks 4-5

My vision didn’t have any more artifacts, but kept improving slowly and steadily over this time. When I went in for my 5-week follow-up, I was measured in my left eye at a little better than 20/20, and the right eye was at 20/15 (better than 20/20).

5 Month Checkup

I had noticed my eyes had kept improving over the first few months and when I went in for my 5-month both eyes were at 20/15 (actually the right was a little better). I really felt like I had super-human vision. I still do. Whenever I talk to people about my surgery, we test our vision against each other, and I’ve always been a lot better. It’s pretty nice especially being able to make out street signs a half-block earlier.

Summary

I really feel fortunate that everything went just about perfectly for me. Other people take a lot longer to heal up and for their vision to settle. It’s often related to how much they have to correct, but not completely.

I have a friend who had to go back for a touch-up at the 1 year mark (it wasn’t the full procedure, didn’t require the 5 days of healing). During the year she had adequate vision, but not great, she wore light prescription glasses for that period. The worst part for her was the perpetual frustration of not knowing whether or not it was going to get there, when, and if it would take a touch up. She was at about -9 in both eyes before the surgery, and even without the perfect vision she was very glad to have had the correction (-.75 to -1 is a lot better than -9). As of a few months past her touch-up procedure, she said she was just about perfect, quite happy. She did spend an awful lot of time going back and forth for after-care checkups and of course the follow-up procedure, all of which was of course with the docs who did her surgery (and that different touch-up procedure). All for no additional cost of course.

So, part of your potential outcome is down to your prescription, but I also tried my very hardest to make sure that I picked the right surgery, by the right doctor, with the right equipment, with the right follow-up, and sticking to the pre- and post-op regime that gave me the best opportunity to heal. I tried to do everything I could to maximize my healing process. I ate well, and drank lots. I took vitamins. I slept as much as I could. I avoided the use of an eye-shield for the light, as I always got sweaty and that just seemed like an invitation for bacteria. I also avoided the use of the pain-drops in the eye, as I was told that can affect the healing process. Of course, I was told that feeling pain stresses the body which affects the healing process quite a bit as well. For me, the T3s were enough to handle the worst of the pain, and I avoided use of the pain-drops all together. Overall, I tried to maximize my self care.

I am certain that luck played a factor in my results, but I’m also certain that some amount of my over-preparation contributed to the great results.

Anyway, this is a magnum-opus, but hopefully it gives you an idea of what you’re in for. Let me know if you have specific questions, and I’ll get you a (shorter!) reply.

Good luck, and keep me posted on your journey!

PS: No guarantees on a shorter reply.

Continued Reading

Here are my posts on PRK and laser eye surgery, continue reading or, feel free to join the discussion in the comments below!

Laser Eye Surgery Primer: Lasik vs PRK
Lasik vs PRK: What the Lasik Doctor Doesn’t Tell You
My Laser Eye Surgery, Part I: PRK Pre-Op Preparation
My Laser Eye Surgery, Part II: The PRK Operation
My Laser Eye Surgery, Part III: PRK Post-Op Recovery (You are Here)
Halos: A Likely Complication of PRK or Lasik    

The post My Laser Eye Surgery, Part III: PRK Post-Op Recovery appeared first on is this your homework?.

Laser eye surgery is a very popular procedure for correcting near- and far-sightedness as well as astigmatism. Since the first techniques were developed in the early 1980s, many millions of people have gone under the laser hoping to eliminate the need for contacts and glasses. I myself underwent PRK in July, 2011. As is my nature, before I leapt, I looked very closely at the available information on laser eye surgery. What I found was surprising, even disturbing.

It wasn’t until I spent a great many hours investigating the procedure in detail, that I realized how stunningly little information is available to those who are performing their own casual investigation into laser eye surgery. I am dismayed at the lack of information or the outright misinformation provided by practitioners of the surgeries, no doubt in order to prevent scaring off their potential clientele.

The truth is that there are a huge variety of laser eye surgeries, all masquerading under one or two common names. If you think there is only one type (or ten types) of laser eye surgery commonly performed, you are seriously under-informed about the entire procedure. For example, two people, each having had the Lasik variety of surgery performed, could have had completely different surgeries, using completely different procedures, and with completely different risks, side-effects, and expected outcomes.

I hope the following article will provide prospective patients a strong base-level of necessary understanding of the currently available methods of laser eye surgery. Rather than trusting what I provide here as gospel, I prefer that the reader take this article as a jumping-off point for their own education.

For reasons that will become readily apparent after reading this article, I strongly recommend against the corneal flap-based Lasik procedures. Ultimately though, you must find your own answers. Before undergoing surgery, you should educate yourself on the risks involved, you should know what questions to ask of a potential surgeon, and most importantly, it is absolutely critical to know exactly why you would choose PRK, Lasek, Epi-Lasik, or especially Lasik.

While I will discuss some important areas of risk, especially the risk differences between the various procedures, this won’t be an exhaustive risk analysis of laser eye surgery. Each prospective patient should find their own answers to these questions through self-guided research and through conversations with their (hopefully independent) ophthalmologist and their potential eye surgeons. It is my hope however that, after reading this article, those looking into the surgery will have a better idea of just what questions they will need to find answers to.

A Brief Look at Eye Anatomy

Before we begin with the details of laser eye surgery, we need to establish the relevant structure of the eye, specifically the cornea, the transparent part of the eye which covers the iris, pupil, and interior parts of the eye.

The cornea is comprised primarily of the Stroma, with a layer of transparent skin, the Epithelium, covering it. The average corneal thickness in a Caucasian is about 540 µm (about 0.5 mm); it is less in Blacks (520 µm) and even less in Asians (490-510 µm). These are average values, and each individual’s corneal thickness can vary by a significant amount. As I’ll discuss further down, these variances can have very large effects on the risks of the various laser procedures.

In addition to performing about two-thirds of the focusing power of the eye (with the adaptive lens performing the remainder), a very important role of the cornea is to provide structural integrity of the eye. When intraocular pressure is too great, or the cornea is otherwise unable to resist against the pressures within the eye, serious conditions such as ectasia or keratoconus (bulging of the cornea, requiring transplant) can result.

Because all methods of laser eye surgery involve some level of cutting or reshaping of the cornea, the cornea’s structural integrity is always compromised; how much depends greatly on which type of laser surgery is chosen. The difference of just how much cornea is cut between the different methods may surprise you, and should be the paramount consideration when choosing a laser eye surgery method.

The Many Flavours of Laser Eye Surgery

The first step in understanding laser eye surgery is to examine the various procedures that fall under the broad umbrella of the term. The variations between different surgeries can be grouped as follows:

1. Where the correction is made and how the site is accessed.
   • Mid-Cornea – Cornea Flap: Lasik
   • Cornea-Surface
     • No Flap: PRK
     • Skin-Only Flap: Lasek and Epi-Lasik
2. How the correction ‘prescription’ or ‘map’ is developed.
   • General Prescription Map
   • Semi-Custom Preset Map
   • Fully Custom Map
3. How the eye is tracked and the laser is aimed.
   • Outside vs Inside Iris Tracking
     • 3D vs 2D Tracking
   • Tracking Speed
4. How the correction is applied to the eye and the size of treatment zone.
   • Correction Zone Only vs Correction Zone with Tapered Edge
     • Correction/Tapered Zone Larger/Smaller than Dilated Pupil

As you can see, each of the major category groups contains a number of choices (and sub-choices) which can drastically affect the surgery performed. This makes for a dizzying variety of possible procedures falling under the Laser Eye Surgery umbrella. While some discussions on laser eye surgery focus on comparing Lasik, Lasek, PRK, etc, even this level of detail covers only a subset of the important differentiators, and decision points, that make up just the first grouping above. In order to truly understand the procedure, prospective patients need to look at each of these areas in detail.

In this article, I will focus on just the first major question: where the correction is made. This is the major differentiator between Lasik, PRK, Lasek, etc. For more information about the subsequent (important!) questions, see my article: My Laser Eye Surgery, Part I: PRK Pre-Op Preparation.

Critical Decision: Correction Site and Access: Lasik vs PRK

The most critical decision in choosing a laser eye surgery procedure is selecting where the correction is made and how that correction site is accessed. The four primary types of laser eye surgery, PRK, Lasik, Lasek, and Epi-Lasik fall within two main categories of where the correction is made: mid-cornea corrections (Lasik) and cornea-surface corrections (PRK, Lasek, and Epi-Lasik). Each procedure (and their sub-types) are refinements on how that correction site is accessed.

While each of the differences between the various procedures warrants careful consideration, this factor alone, where the correction is made, has by far the greatest impact on overall short-term and long-term risk of the surgery.

Mid-Cornea Correction: Lasik

The Lasik family of eye surgeries, including the various ‘all laser lasik’ procedures (but not epi-lasik, see below) all involve cutting a flap into the cornea (some with a blade, others with a laser), folding that flap back, performing the correction mid-cornea by burning or more accurately vaporizing a lens shape in your cornea, and then finally re-seating the corneal flap. These mid-cornea procedures are relatively new compared to the much older cornea-surface procedures.

As illustrated above, the flap-based correction method involves cutting a significant way through the structure of the cornea, before any corrective shaping is performed. As a result of this, Lasik mid-cornea procedures are always more invasive, significantly compromising the biomechanical integrity of the eye.

This graphic illustrates an average 150µm cornea-flap cut (see the section below on the variability of Lasik cornea flaps), with 1-10 diopter mid-cornea corrections. Note that, since the creation of this graphic, among some practitioners, the 250µm ‘safe’ residual thickness is being revised to 300-350µm.

Cornea-Surface Correction: PRK, Lasek, & Epi-Lasik

The cornea surface procedures, PRK, Lasek, and Epi-Lasik, all involve removing only the epithelium, the skin layer which covers the cornea, and then performing the correction by reshaping the surface of the cornea. With PRK (pictured below), the skin layer is loosened by an alcohol bath, removed completely via a blade, and then allowed to grow back over the cornea after surgery. With Lasek and Epi-Lasik, the skin layer is loosened by an alcohol bath (all Lasek and some Epi-Lasik), a skin-only flap is created via a blade, and then re-seated overtop the cornea after surgery.

As illustrated above, the cornea-surface correction method involves lifting off the epithelium, the skin layer, then correcting the surface of the cornea. As a result, the cornea-surface procedures are the least invasive, retaining the highest degree of biomechanical integrity of the eye.

Each of the surface-ablation methods are quite similar, with the only differences being how the skin is removed and whether or not it is reseated after surgery. Check out the Pros and Cons section below for a more detailed breakdown of each.

This graphic illustrates 1-10 diopter cornea-surface corrections. Note that, since the creation of this graphic, among some practitioners, the 250µm ‘safe’ residual thickness is being revised to 300-350µm.

Serious Concerns with Lasik

If you haven’t already realized the serious concerns with Lasik, concerns arising over the significant difference between Lasik vs PRK (and the other cornea-surface procedures), I urge you to think intuitively about the procedures.

Use your instincts when assessing the wisdom of severing a significant portion of the cornea. Ask yourself what purpose the cornea serves (See: ‘A Brief Look at Eye Anatomy’ above) and what potential consequences can arise from compromising it so significantly. Bear those thoughts in mind as you read the following areas of concern with the Lasik procedure.

1. The Lasik Cornea Flap Never Heals

First, and most importantly, the ugly truth about Lasik is that the cornea flap never actually heals. The cut is permanent. The cornea is forever compromised. You may hear Lasik surgeons repeating a familiar talking-point that: “Within two years, the lasik flap will be strong enough that any force significant enough to dislodge it, would injure an untreated eye.” This is a lie. It’s a lie told over and over again by countless lasik doctors. They sleep at night by telling themselves that the wound does ‘heal’ in that the skin heals and it creates a bond, however the cornea itself never actually heals, never rebinds together, the flap is permanent.

The cornea flap never heals, only the skin layer overtop of it. There are numerous reports of quite mild trauma, even actions as light as finger rubbing, that have dislodged the flap even up to 14 years after surgery.

As you’ll see in the following section, the potential consequences of that permanently thinned cornea are incredibly serious.

2. Higher Risk of Permanent Vision Loss Due to Ectasia with Lasik

Ectasia is a stretching and bulging of the cornea, resulting in rapid vision loss, often requiring corneal transplant to treat. The causes of ectasia are manifold, but a significant rise in post-Lasik ectasia has been seen.

The Lasik community has taken the issue very, very seriously. The most frequent topic being discussed by Lasik surgeons in journals and at conferences is the development of methods of pre-screening patients to reduce the rate of post-lasik ectasia.

The true rate of post-Lasik ectasia may never be known, but estimates have peaked at the 0.6-0.9% rate and with newer screening techniques in place, the current rate is estimated to be about 1 in 2,500.

With millions of lasik surgeries being performed, even a 1 in 2,500 chance of debilitating vision loss is far too high for my taste. And that’s only if Lasik doctors turn away as many patients as possible. The risk factors leading to ectasia are still being studied, but the residual thickness of the cornea, coupled with the amount of correction are universally cited as the prime factors. The rates of ectasia are significantly reduced after PRK and other cornea-surface procedures, where less of the cornea is compromised.

Again, the fundamental problem with Lasik rears its head, the cornea is critically important for maintaining the structural integrity of the eye, yet as the two graphics above illustrate, significantly more cornea is compromised by Lasik than by the cornea-surface procedures such as PRK. Yesterday’s wisdom was that 250µm was a ‘safe’ residual thickness, but today’s best practices suggest 300-350µm. What will tomorrow’s ‘safe’ be? Obviously the Lasik industry is coming around to what should be intuitive to everybody, that the more of the cornea that is compromised (both by the flap cut and by the correction itself), the less it is capable to maintain the proper shape of the eye.

Prospective patients of any medical procedure understand that there are risks. They understand that there is a trade-off between the potential upside of the outcome versus the potential pitfalls of side-effects. However, many prospective Lasik patients aren’t ever aware that there are alternatives that provide those same upsides, without the serious pitfalls. Lasik doctors will tell you that incident rates of ectasia are low, but they don’t tell you that they are many, many times higher with Lasik than with PRK.

I strongly recommend that anybody considering Lasik, do some serious digging into the phenomenon of post-lasik ectasia. It’s an incredibly serious condition that simple common sense (as well as serious scientific study) reveals is more likely to occur with mid-cornea Lasik procedures, than with cornea-surface PRK procedures.

3. The High Variability of Lasik Flap Thickness

With Lasik, before the correction is even applied, a significant amount of the cornea is sliced into. This is done either via a kind scalpel called a “microkeratome”, or via a specialized laser used only to make the flap, an “IntraLase” laser. However, the thickness of this flap is never consistent from patient to patient, indeed it can vary greatly depending upon both the skill of the surgeon and upon which Lasik variant, microkeratome or IntraLase is chosen (with the latter being somewhat more precise).

Even with the best surgeon using the latest flap-cutting technique, there is still quite a bit of chance involved in just how much of the patient’s cornea is going to be cut into to make the flap. For a somewhat frightening exhibit of this, refer to the abstract from the paper below, which describes differences in the ‘reproducibility’ of Lasik flap thickness between mechanical blade and IntraLase laser flap-cutting methods.

What frightens me about that report is that, while IntraLase flaps are off by more than I’m comfortable with, the flaps cut by surgeons using mechanical blades were sometimes off by huge amounts from what was being aimed for; both types of blade had a range of actual cut thicknesses wider than 115µm. Even if you are a ‘good candidate for lasik’, the high variability of the flap thickness could leave you with a much too thin cornea. When aiming to cut only 130μm into the cornea, sometimes cutting over 70µm too deep is an absolutely staggering error. Indeed using one type of mechanical blade, the incidence rate of “thick flaps”, flaps greater than 170μm, which means cutting significantly deeper into the cornea than intended, was over 10%. Scary stuff.

Indeed, due to the unpredictable flap thickness, the Lasik journals recommend surgeons measure the thickness of the patient’s cornea flap mid-surgery (a procedure called pachymetry), aborting the procedure if the flap thickness will result in a too-thin cornea. Makes sense right?

Well most Lasik surgeons don’t do this.

That to me is frightening. There is a huge random variation in flap-thickness, but most doctors don’t even measure the flap. This means most Lasik surgeons have no idea how much corneal thickness their patients have left after surgery.

4. Retreatment is Far More Complicated After Lasik

Because a significant part of the cornea is compromised when cutting the lasik flap, there is obviously significantly less cornea thickness after Lasik. Additionally, because of the high variability of that flap thickness, it is difficult to determine in advance how much flap thickness will remain. This means that, not only is the structural integrity of the eye lessened, and unpredictably so, but the options for retreatment are also severely limited. There is only so much cornea that can be safely burned away, and since Lasik already starts much deeper into the cornea than the cornea-surface options, immediate retreatment to correct errors in the procedure or future retreatment to re-correct changing vision are far more risky, sometimes not even possible.

Even a single Lasik treatment is simply not an option for people with thinner than average corneas or significant vision prescriptions. For these people, the much less risky cornea-surface treatments (PRK, Lasek, epi-Lasik, etc) are still a safe and recommended option. For those with thin, but supposedly ‘safe enough’ corneal thicknesses, they’re rolling the dice as to whether their post treatment eye will still be ‘safe enough’ for retreatment or whether they might be stuck with uncorrectable vision forever.

Not only that, but there can be serious issues with epithelial ingrowth under the flap when a retreatment is attempted. Epithelial ingrowth after Lasik is not exactly unheard of without retreatment, but it is significantly more likely when performing a Lasik retreatment.

Of course, nobody wants a retreatment to correct the first procedure, but it can be necessary. “The re- treatment rate after primary LASIK varies in different studies and is approximately 6% to 20%.” And, because you’re working with a much more compromised cornea after Lasik, the options for retreatment are significantly more complicated.

5. Severe Eye Dryness is Far More Common with Lasik

Many people who have never had laser surgery have dry eyes. It is annoying, sometimes painful. Few of them have found eye dryness severe enough to undergo a surgical procedure to implant plugs to help hydrate their eyes. This is the “dry eye” that is meant in laser eye surgery journals. It is not trivial.

Immediately after my surgery, I got a feel for this sort of severe dry eye. It lasted a few days while my epithelial layer re-grew after PRK. It was not something I would have wanted to live with for the rest of my life. Unfortunately, many Lasik patients have to endure this, or have additional surgical procedures to help mitigate it.

Lasik cuts much deeper into the cornea. It severs a lot more nerves than PRK/Lasek/Epi-Lasik. And of course, the deeper you cut (which is unpredictable due to randomness of corneal flap cuts), the greater chance you have of cutting so many nerves that your eyes no longer produce enough tears. A staggering 1.3% of Lasik patients had to have plugs surgically embedded in their eyes to help offset severe and painful eye dryness.

No PRK patients had to have this done. PRK leaves a more intact, more healthy cornea.

If Lasik is so dangerous, why is it so popular?

This is a question worth asking. If Lasik has higher rates of very serious short- and long-term side-effects, why is it so popular.

Lasik is an easier sell. Lasik patients feel ‘good as new’ just a day or two after surgery. With little discomfort in recovery, Lasik patients tell other prospective patients how easy it was. How great they see the next day. These patients have no idea how much riskier their procedure is over PRK/Lasek/Epi-Lasik, they just know they’re fine now. Lasik is the very definition of a ‘quick-fix’, often it appears easier, but serious problems can occur in the long run.

With PRK, the skin layer of the cornea is removed. Like removing any top-layer of skin, that area is going to be raw until it regrows. PRK has a five-day recovery while your cornea regrows a fresh, seam-free layer of skin under a protective bandage contact lens. These five days are uncomfortable, and painful without medication. Additionally, the skin that grows back is a little swollen for a week or two, this causes slight vision artifacts (ghosting, faint double-images) until the new skin over the cornea completely heals. I describe the preparation and healing process in detail in my series documenting my experience My Laser Eye Surgery, Part I: PRK Pre-Op Preparation.

With the newer Lasek and Epi-Lasik procedures the recovery time and experience matches that of Lasik. In these procedures the epithelial skin layer is not completely removed. Instead the skin layer is folded back in a flap (similar to Lasik, but it’s a skin-only flap, not a corneal flap), and then after the correction is made to the cornea, the skin flap is laid back. This is less traumatic to the cornea’s skin, but has its own minor complications with that flap. These complications are significantly less serious than corneal-flap complications. Often, the worst that happens is the Lasek skin-flap simply has to be removed, effectively turning the procedure into a PRK procedure.

I chose to stick with PRK over Lasek/Epi-Lasik (but never Lasik!) mostly because it was the oldest and most studied procedure and the surgeons were more experienced with it. If I was looking at the procedure today instead of in 2011, I may well have chosen an epithelial-flap procedure like Lasek. I would never contemplate the Lasik corneal-flap procedure.

So, in the past there was a significant difference in recovery between Lasik with its corneal-flap, and the safer PRK, with its epithelial regrowth. Now however, there is little difference in recovery between the corneal-compromising Lasik and the corneal-conserving Lasek/Epi-Lasik.

Of course, doctors are still performing Lasik, when in my opinion there is absolutely zero benefit (even over the short term) to the patient compared the alternatives.

So why is Lasik still performed?

Well, it costs money to upgrade a practice from Lasik. New machines, new training, new techniques. What’s the business incentive for a doctor to do this? There is little. Until Lasik is removed as a medically authorized procedure, doctors can tell themselves that incidents of complication are low (which is true, but many times higher than other, equally effective procedures), and continue earning huge amounts of money offering the Lasik quick-fix.

And Lasik is a powerful ‘brand’. When people think laser eye surgery, they think Lasik. Indeed some PRK and Lasek providers are advertising their clinics as Lasik clinics, capitalizing on the brand recognition, while recommending the safer procedures.

What is a prospective patient to do?

The vast majority of prospective patients will never research laser eye surgery. Will never even be aware of the issues described above. That to me is frightening.

I hope the information I’ve provided helps the people who have found this page. Prospective patients should take this information and go do their own research. They should ask their local Lasik/PRK clinics questions about these complications. They should take those answers and try their best to find out how true they are.

Ultimately prospective patients are going to have to make a decision for themselves. Hopefully I’ve helped to make it a well-informed decision.

Good luck, and keep me posted on your journey!

Continued Reading

Here are my posts on PRK and laser eye surgery, continue reading or, feel free to join the discussion in the comments below!

Laser Eye Surgery Primer: Lasik vs PRK
Lasik vs PRK: What the Lasik Doctor Doesn’t Tell You (You are Here)
My Laser Eye Surgery, Part I: PRK Pre-Op Preparation
My Laser Eye Surgery, Part II: The PRK Operation
My Laser Eye Surgery, Part III: PRK Post-Op Recovery
Halos: A Likely Complication of PRK or Lasik    

The post Lasik vs PRK: What the Lasik Doctor Doesn’t Tell You appeared first on is this your homework?.

In July of 2011, I had PRK laser eye surgery done. Shortly before, I wrote up a Primer on PRK vs Lasik that the reader may find interesting (TL;DR: Lasik is a dodgy quick-fix, avoid it, stick with PRK). Since then I expanded on the differences between PRK and Lasik, which hopefully provides the reader with all the questions they should be asking their laser eye surgeon: Lasik vs PRK: What the Lasik Doctor Doesn’t Tell You.

Before I went into the surgery, I did a great deal of research and found a dizzying array of variables that the prospective patient should take into account before choosing whether to have the surgery and where to have it performed. Resulting from this research I detailed the critically important questions that need to be asked before going under the laser: My Laser Eye Surgery, Part I: PRK Pre-Op Preparation. In this article, I describe the PRK procedure itself and the subsequent recovery period. Edit: Here is the third part, detailing my post-op recovery: My Laser Eye Surgery, Part III: PRK Post-Op Recovery.

Summary First

It has been about three years since my PRK surgery, and I still couldn’t be happier. I reached better than 20/20 vision three weeks after surgery, and have had practically no side-effects with my 20/15 vision since around the four-week mark. I have not tested my vision for quite a while, but I don’t feel as if I’ve had much if any fall-off (your eyes will naturally get worse whether you have surgery or not). I still have better vision than I ever had before, and regularly am able to ‘show-off’ when discussing my PRK by reading things at distances others cannot. Before the surgery, I was about -4 in each eye with an astigmatism of around 1.00. I see much better now than I did with glasses or contacts before and my eyes are actually less dry and less red than they were before surgery. I have had zero regrets about the procedure.

While I have been on the ‘best case you can hope for’ end of the bell-curve of results. *knock wood*, I think perhaps that my efforts to assist in my healing provided at least some benefit to that experience. Along with my account of surgery and recovery, this article will also detail the steps I took to give myself the best possible chance to recover optimally, in the hopes that readers may benefit by it.

Day 0: Operation Scorched Orbs

Pre-Op: Peak Anticipation

The procedure was crazy fast. The time between arrival at the clinic and departure for home was about 45 min, and that’s including filling out the necessary paperwork, waiting 5-10 min for the pre-operative anesthetic drops to take effect, post-operative exam, etc. The actual procedure took about 5 to 10 minutes, maximum.

After I was signed in and waivered, I was brought into an examination room for one last look at my eyes, to ensure that nothing had changed and that I was still Go for Surgery. With the green-light, I was led to a bed in a quiet pre-op prep room and given some anesthetic drops for my eyes. I was then left alone for ten minutes, just outside the operating room, so that I could obsess once more over the risks of the coming procedure the anesthetic drops could take effect.

At length I was ready. A nurse fetched me and brought me into a medium-sized room that was dominated by the sight and sound of a large, droning machine. The machine itself was a desk-sized cabinet with a manhole-sized robotic surgery on an arm overhanging an attached bed. The contraption, made for a single purpose, sprouted a host of digital and optical display instrumentation, control knobs, and ventilation tubes. The sound it emitted was somewhat lower on the tonal register and decibel scale than a vacuum cleaner, but above in volume and pitch the buzzing of a wasp nest. It was a blanketing white noise, loud enough to soothe jangled nerves, and loud enough to isolate the room from sounds coming from without (coming from within too, for that matter). The machine would not have looked out of place on a Star Trek sickbay set. Come to think of it, it would not have looked out of place on the set of a Borg Cube assimilation chamber.

The surgeon introduced himself and laid me on the bed. He proceeded to give a quick overview of the procedure, what I would experience, what it would feel like, and what was needed of me. The surgeon’s description of the process had no surprises for me, I knew the procedure fairly well, even having gone so far as to watch videos of the surgery online, and when he asked if I had any questions, I replied that I hadn’t.

Prior to this, I had been prepped by both technicians and ophthalmologists, they had given me the necessary information on the procedure, it’s risks, and it’s post-operative care, but this was the first time I’d been told the ‘nuts and bolts’ of using a high-powered laser to burn a new shape into my cornea. Based on my prior research, I was likely more informed than the vast majority who had laid on the bed before me. As I’ve mentioned previously, my one criticism of all the laser eye surgery providers is that they are not overly forthcoming with details on risk, complication, and actual procedure. They were all quite helpful when I asked for greater detail, or had specific questions (if they’re not, run the other way!), but none were forthcoming with more than the minimum required. I suppose this is necessary, as most truly don’t want to know more than the very high-level picture of risk and reward. The reader would be forewarned to do their own research before going under the laser, though I suppose that message is preaching to the choir in this account.

After the run-down of the surgery, and after one last chance to ask questions or back out, we began the assimilation surgery.

PRK Surgery: Blink and You’ll Miss It

A nurse inserted Clockwork Orange eye-priers, and dabbed a few drops of lubricant drops. Then, the bed I was on was swung under and into the machine. From above, the large, round robotic surgeon looked mostly benign, but from beneath, the beast’s many-eyed, many-fanged face felt uncomfortably close. That said, as a lover of all things novel, technological, and physiological, the dozen different lights and probes and nozzles of this technological terror were at once intimidating and fascinating. My heart-rate was at its highest at this point of Peak Anticipation.

As the procedure commenced, I was a little surprised when the very first part of the purportedly “no-touch” procedure was the doctor placing a ring-like device on my eye (to be filled with an alcohol solution for effectively ‘delaminating’ my epithelial from the cornea), then using a scalpel to score the epithelial around it. I’d known that some procedures use laser, others scalpel for removal of the skin-layer. This isn’t a critical part of the procedure (unlike the cutting of the Lasik cornea-flap, in which the laser is much safer than the scalpel, but you shouldn’t even consider Lasik and its cornea-flap anyway, so never mind). I wasn’t overly concerned about this, but I did have a brief, wry thought involving “no-touch” and “my ass”.

I wasn’t too nervous once things got started. I’d imagine it’s like bungie-jumping or sky-diving, the nerves peak, then fall away when you step into oblivion. I suppose there’s no evolutionary advantage in nervousness past the point of no return, instead the body goes into a “let’s do this” mode, though the message is probably less verbal and more atavistic.

The surgery was quick, and fascinating. I had an unparalleled view of the operation, best seats in the house. While fully manageable sober (I declined the happy-pill), the procedure was a bit unpleasant for a few different reasons. Readers will have to decide for themselves whether they’d rather have the sedative.

The first unpleasantness was that, despite the knowledge that they had milisecond 3D tracking of the outside of my iris (the best available at the time, see Part I), I was more than a little nervous that I’d screw myself up by losing track of the orange target light that I had to stare at. In practice, this isn’t really an issue, the laser is supposed to detect any movement off-axis and halt the procedure within a millisecond or so. Even armed with that knowledge, I was still apprehensive before starting. And this worry raised itself during the procedure itself, as I kept wondering, “Hey did I just move my eye?” It was difficult to tell with all the activity, water, implements, and flashing lights going on in your eye, and it left room for groundless doubt to creep in. In the end, there were no issues of course.

The second less-than-pleasant aspect of the surgery was the smell. Awful. Ever had your tooth drilled at the dentist? That’s the smell. Worse for me, I have a beard. And because you can’t wash your face for a while (don’t want to risk bacteria getting flushed into your eyes), for three days, every time I disturbed my beard I’d get a fresh waft of Charnel No. 5.

The third, and most unpleasant aspect of the surgery is the fact that there is an awful lot going on to your poor eye. While the eye itself is completely numbed, three parts of the procedure were uncomfortable: the Clockwork Orange eyelid clamp; the epithelial removal ring, which had to press fairly hard onto your eye (stick your knuckle into your eye pretty good for an idea); and the ice-cold water bath immediately after the laser had done its work (instant, terrible ice-cream headache, centred in your eye, thankfully lasting only a few moments).

Once it was all over (I’d say in a blink of an eye, it was so quick, but of course blinking was prevented by surgical clamp), I took a breath, gave a brave thumbs-up to the surgery team, and we started all over again on eye two. The second go-round was easier, as I knew what was coming, but I found myself dreading the ice-water bath more than all the other ocular indignities. It wasn’t that bad, but like licking a nine-volt, your body remembers its first time jangling raw nerves and is naturally hesitant the subsequent times.

Recovery: Into the Heart of Darkness

Immediately post-op, I could see fairly well. But hazy. 100x better than not wearing contacts. I could tell my vision was corrected significantly, but it was like looking through dense fog. Within about 10 minutes, on the way home, the light sensitivity kicked in. Even with eyes shut tightly, sunglasses on, my head down low in the car, and a hat pulled low over, it still felt super bright. And I mean painfully bright. I just wanted to go home and get in the darkness, fast.

Once home, my wife commenced Operation Grow Op, by tinfoiling all the windows. I’d heard some found this necessary, and I figured I’d hold off. I regret the decision, especially in eye-scorching sunny mid-July. My advice is to do this in advance, you won’t regret it. It was bad until it got dark inside. Even the tiniest slit in the corner of the window was crazy bright to me, even while wearing sunglasses. Be prepared to be a mushroom for 5 days.

Overall, aside from the light sensitivity, there was almost no pain. My eyes were definitely sensitive, they were abused pretty good, but the pain drops they give you pre-op lasted a while, and I was thinking I’d take a T3 that night, but didn’t have to. I took half of one of the sleeping pills they gave me and slept well all night. I didn’t use an eye-shield at all, just to help avoid bacteria. I’ve slept with one before and my face was a sweaty steamy mess.

Note: My surgery clinic gave me a little green bag that had all my drops (antibiotic, steroid, pain, lubrication) each well labeled with giant numbers on them listing their dosage intervals. Also in the bag were enough sleeping pills to last a week, and a load of T3s. You’ll be dipping into the bag for drops at least every 4h for the next 5 days, so you will grow to love/hate your Little Green Bag.

This is an important one to ask about too, check to make sure how much of the above your clinic will give you on the day, and how much you’ll have to get yourself. If they don’t provide it, I strongly recommend you getting all of your drops and drugs in advance. You literally will not be making any trips to the store for the next few days.

Extra Important Note: Standard eye drops that come in the medium size (30ml) bottle *all* have preservatives in them. The non-preservative ones don’t come in sizes that are greater than 1ml (to avoid infection). You’ll be using a ton of these drops to keep your eyes lubricated, and I realized way too late that using the standard drops that much just dries your eyes more. On Day 2 I started to notice that my eyes felt drier shortly *after* using the drops than they had been before, and on Day 3 I confirmed it. That’s the preservatives. Late on day three I had my wife pick up some of the non-preservative ones (available at your local drug store) and it helped immensely. Check with your doc first, but if I had to do it over again, I’d only have used them. The best ones I found after researching online were Refresh brand, specifically the “Celluvisic” variety (they’re about $0.50 per three dosages). They’re fairly thick and goopy, but they actually have less in them than the standard drops, and they were miraculously more comforting.

Continued Reading

Here are my posts on PRK and laser eye surgery, continue reading or, feel free to join the discussion in the comments below!

Laser Eye Surgery Primer: Lasik vs PRK
Lasik vs PRK: What the Lasik Doctor Doesn’t Tell You
My Laser Eye Surgery, Part I: PRK Pre-Op Preparation
My Laser Eye Surgery, Part II: The PRK Operation (You are Here)
My Laser Eye Surgery, Part III: PRK Post-Op Recovery
Halos: A Likely Complication of PRK or Lasik
    

The post My Laser Eye Surgery, Part II: The PRK Operation appeared first on is this your homework?.

In July of 2011, I had PRK laser eye surgery done. Shortly before, I wrote up a Primer on PRK vs Lasik that the reader may find interesting (TL;DR: Lasik is a dodgy quick-fix, avoid it). Long before signing up for the surgery, long before going under the laser, I did a ton of research. I had been interested in having it done since 1998, and only got it done last Summer, when I thought the tech was finally there (I felt it had been for the past few years) and when I finally had the time and money.

This will be the first of several posts which serve as a journal detailing my experiences with PRK. I’ll update this page with links to the subsequent journal entries. (Part 2 is up! Details of the day of surgery here: My Laser Eye Surgery, Part II: The PRK Operation, and so is Part 3, detailing the post-op recovery: My Laser Eye Surgery, Part III: PRK Post-Op Recovery.)

I am also not going to argue the case of PRK vs Lasik any further in these accounts, but I am planning for sometime in the future a more comprehensive breakdown of the differences between PRK, Lasik, and the other forms of surgery. Edit: Here it is: Lasik vs PRK: What the Lasik Doctor Doesn’t Tell You.

I am not going to mention any names, as I don’t want my accounts to be mistaken for an endorsement for, nor a warning against, any particular surgery centres. Hopefully this information will be sufficient for any prospective patients to know what questions to ask of their PRK surgeon, and to know what they might be in for with the procedure.

Summary First

It has been over 14 months since my PRK surgery, and I couldn’t be happier. I reached better than 20/20 vision three weeks after surgery, and have had practically no side-effects with my 20/15 vision since around the four-week mark. I was about -4 in each eye with an astigmatism of around 1.00. I see much better now than I did with glasses or contacts before and my eyes are actually less dry and less red than they were before surgery. I have had zero regrets about the procedure.

It’s important to understand though, that my experiences are at the very far end of the bell-curve of results. Relatively few people wind up having quite as good an experience that I’ve had, and most people take longer to heal up or for their vision to cure. Some require various levels of retreatment and some have serious side-effects. Your mileage may vary. This may be a glowing endorsement of the procedure, but it is not a guarantee. You should absolutely look into it carefully, using this account as an idea of what questions you need to answer before you decide to have it done.

As I wrote in the “On Irony and Selection Bias” section in my PRK vs Lasik Primer, “Whatever my outcome, whatever the outcome of your cousin, your co-worker, or everybody you know, the dice are being rolled with each procedure, and each procedure has its different risks. These risks exist and must be looked at on aggregate for each procedure, hopefully before you go under the laser.”

Choosing a PRK Surgeon

This is the most important part of the laser eye surgery process. I’ll tell you from the outset, that cost should absolutely not be a factor. The price of the surgery is largely unrelated to the quality that you can expect. While the cheapest in town probably won’t be the best, neither will the most expensive likely be. Ignore cost entirely.

I live in Vancouver, BC, and from my extensive research, I settled on two places in the area that I’d even consider for my PRK surgery. Both clinics had excellent doctors who had many thousands of surgeries performed, both were very highly recommended by ophthalmologists in town, and both were quite a large step above the rest of the players in town with regard to equipment and experience. However, there was a fundamental difference between the two clinics that made the choice simple for me, and that choice actually went against many of the ophthalmologist’s recommendations.

The fundamental difference was that the clinic I went to performed all of the post-operative after-care, while the alternative clinic did not, instead out-sourcing the after-care to your own ophthalmologist. I’ll try to explain why that difference is so key with PRK, and why perhaps ophthalmologists may have been more likely to recommend the alternative clinic over the one I went to.

While it sounds relatively trivial, in actuality, a huge portion of the outcome of PRK surgery relies on the decisions made during the post-op after-care period. Decisions surrounding the frequency and duration of the steroid drops you take play a huge factor in the healing process. All laser surgeries over-correct a little, anticipating the eye to heal, regenerating some of the cornea that is shaved off for the correction. If you took no steroid drops, you’d heal over a great deal of the correction fairly quickly. So, how much of, how often, and how long you take the steroid drops will determine where the healing process stops. They try to aim for just the right amount of healing that stops at your 20/20 (or better) vision. Everybody heals differently either due to genetics or environmental circumstances, so the custom-tailoring of the steroid dosage is critical to getting the best out of the surgery.

If all that after-care is done by your own ophthalmologist. Even if your ophthalmologist has seen a hundred PRK patients (in reality likely nowhere near that many), then he’s going to have very limited experience. He’s largely going to be following procedure that is generically tailored to everybody, and won’t necessarily be able to tailor the treatment to your particular healing rate.

With my surgery, all the after-care was by the doctors at the laser-surgery clinic that performed my PRK surgery. They were working with the knowledge of tens of thousands of surgeries performed in-house. I had follow-up visits and eye tests at the 1-day, 3-day, 5-day, 5-week, 5-month, and 1-year marks (all included in the price, not that price matters really). I felt far more comfortable having the after-care decisions made based on that mountain of experience, than I would have had it been an ophthalmologist that had little experience or training with laser eye surgery after-care.

It is important to remember that with PRK it’s that first 3-5 days post-op that makes such a huge difference in overall results. For example, on my day three visit the doctor reduced the frequency of the steroid drops in both eyes, but reduced them more in one eye than the other. As is common, they were healing at different rates. On day 5 he stopped the steroid drops in one eye, and had me do just a little bit in the other eye for a couple more days.

That aspect was crucial, had the post-op medication schedule not been custom-tailored to my day-to-day progress, I wouldn’t have nearly as good vision right now, even with the identical surgery performed.

I’d strongly recommend you seek your surgery at a clinic that has a lot of experience and performs its after-care in-house. They will have so much more institutionalized knowledge. And that knowledge matters.

So, while the alternative clinic has an outstanding doctor who has done many thousands of treatments, they didn’t perform the follow-up after-care, which is so crucial. What was odd was that while the ophthalmologists around town would universally approve of both the clinic I went with and the alternative, most of them recommended the alternative clinic that performed no after-care in-house.

The cynic in me says of course every ophthalmologist in Vancouver will recommend the alternative. They not only have a great surgeon, but then they get the follow-up care. There’s significant money in it for them, if they do the follow-on treatment. Whether cynical or not, it’s naïve to think that that wouldn’t influence their decision.

Other Important Questions to Have Answered

As part of choosing the right PRK surgeon and clinic, I recommend you get satisfactory answers to the following questions, before you go under the laser. You’ll have to ask the questions, as they will generally not be forthcoming on their own. I suppose if they gave all this information up front, almost nobody would go through with it. Plus, a lot of people just don’t want to know, and are happy to go in with eyes closed, so to speak.

It’s also important not to save these questions for surgery-day. You’ll be too nervous, and you’ll likely either forget what to ask or be caught up in ‘go-fever’ and not consider the answers carefully enough. The answers you get to these questions need to be considered carefully, and will in large part be necessary in determining who to go to for your surgery.

I’ll give a bit of indication why the questions are important, but if you don’t fully understand why these answers are necessary, I recommend a little more research.

1: What is my dilated pupil size?

This is important in comparison with the answer to the question about treatment zone below. They will generally measure your dilated pupil size on your first consultation visit, but likely only in a mildly dark room and without much time for your pupil to adjust. As a result, take this measurement as a somewhat smaller estimate of your actual fully-dark pupil size.

2: What laser system is being used for mapping, tracking, and correcting the eye? What version of each component is used? What is the latest version of each component?

Not all PRK laser eye clinics use the same laser systems. There are several available. Further, not all clinics are using the latest version of their particular system. There have been significant advances in the technology in the past several years, but sometimes a clinic will spend more money on it’s flashy waiting room, instead of upgrading it’s several year old equipment. The answers to these questions will not mean much to you, but you can then enter them into google to verify and compare the system being used against the latest equipment from that manufacturer.

3: What is the size of the corrected, non-tapered treatment zone in the procedure? What is the size of the tapered transition zone of the procedure?

Make sure your pupil size isn’t substantially bigger than the corrected, non-tapered zone! The ‘tapered transition zone’ doesn’t really provide the actual correction and really shouldn’t be compared to your dilated pupil size. You need to ask for it, so that you make sure that size isn’t being passed off as the ‘corrected’ zone.

For example, my fully-dialated pupil is slightly wider than the corrected treatment zone available from any of the laser eye systems. The transition zone covered it, but I knew that didn’t mean much. The laser system at the clinic I went to were the latest models as of when I had it done, with the largest correction zone available (plus transition zone, but I didn’t count that). The alternative clinic I looked at used a different system, which had a slightly smaller treatment zone, and that was another factor that ruled them out.

I knew going in what having a slightly larger max-dilated pupil than the treatment zone (not tapered zone) would mean. In complete darkness, some of the light entering my eye is not fully corrected, so it’s blurry. This results in really clear lights with a slight blurry halo around them. I decided I was good with this, because the difference was small. Now, after surgery, If I’m in my bathroom at night in complete darkness, I see a halo around the green LED in my safety-outlet. However, when I put the light of my cellphone’s screen on (pointed away from me), it brightens the room just enough that my pupils contract a tiny bit and all the light is going through the correction zone, and therefore there’s no halos. The halo around the light literally shrinks to nothing at all as my pupils contract a bit. This only happens for very bright lights in near total darkness. In real-world situations like driving or walking around at night, there’s way more light than pitch-darkness, so I have zero halos.

4: Is a custom ‘map’ of my prescription measured (WaveFront, etc)? Is this map used to create a custom correction for each of my eyes, or is this map only used to select the nearest ‘preset’ correction?

Some laser systems used by laser eye clinics advertise a WaveFront or custom map, etc, but the custom map of your eye isn’t actually used to create a custom correction for your eye. Instead it is only used to select from a preset correction. Obviously the latter will result in a less tailored solution for your eye.

5: What eye tracking system is used? Does it track the inside of the iris, or the outside of the iris? How many times a second does it track? Does it track in 3D or 2D?

No matter how good a correction map is being applied to your eye, it’s useless if it’s not aligned as perfectly as possible. In the old days of laser eye surgery, the patient had to stare at a reference light and any movement would result in a misalignment of some of the correction pulses. Modern laser systems track the eye and adjust or stop if the eye moves. But, not all are created equal.

Some laser systems in use track only the inside of the iris, which varies wildly during treatment (the iris is constantly dilating and contracting in reaction to all the prodding, light flashes, and emotional reactions). That one’s a deal-breaker. Avoid any system that tracks the centre of the pupil or against the inside of the iris. Most of the latest laser systems will track on the outside of the iris, which is a far more reliable marker, as it does not vary, except with eye movement.

That leads to the frequency of tracking and the nature of movement that can be tracked. Some systems track eye movements and adjust/stop the corrective laser faster than others. Some systems only track in 2-dimensions, while others track movements in 3-dimensions. Obviously, you want the laser to adjust as quickly as possible to eye movements in any direction

6: Which doctor will be performing my surgery?

Once you’ve selected the PRK clinic based on the experience of the doctor, the quality of the after-care, and the equipment being used, you then have to make sure that you know which doctor in the clinic will be doing your surgery. Most clinics have more than one doctor in house, often where one of those doctors has significantly less experience than the head doctor. I wouldn’t necessarily rule out getting my surgery done by a doctor with only a few hundred operations under his belt, because in reality the actual procedure itself is a relatively small part of the overall process, and that doctor is relying on equipment, settings, best practices, and all the expertise that is accumulated in-house. But that said, I want to know who will be performing the surgery and make my decision with that knowledge.

7: What drugs, drops, etc will be provided, and which do I need to get myself?

Where I went, everything was provided in a little bag that I brought home. This included lubricating drops, antibacterial drops, steroid drops (all labeled with large, clear dosage instructions), pain drops, Tylenol-3 painkillers, sleeping pills, a spare pair of ‘bandage contact lenses’, and a pair of over-the-glasses sunglasses. After surgery, I would not have wanted to make any stops on the way home to get any of that. If your clinic does not provide them, then you should make sure you purchase them in advance.

Pre-op Preparation

After you’ve booked your surgery, while you’re going through the two weeks of not wearing contact lenses, the waiting game begins. This is the opportunity to rehash everything you’ve already looked into. It’s the last time to avoid any regrets. You can read up on the statistics, the horror stories, and the success stories. It’s never too late to ask more questions or delay if you’re unsure.

It’s also the time you can spend trying to give yourself the best possible leg-up towards a successful surgery.

Since so much of the procedure is the healing up afterward, I did anything and everything I could think of to help my body out on the healing front. I started taking a bunch of multi-vitamins and omega-3 fish-oils a couple days before surgery and for a few weeks afterward. I also made sure that I was super-well hydrated before and after the procedure and during the healing. I made sure I was drinking more than enough, making frequent trips to the washroom. I made sure that I slept well and that I ate well. I did pretty much anything I could do to help my body’s healing.

I’m not sure how much of all that over-caution helped my optimal recovery, perhaps very little at all. But I am sure that it certainly didn’t hurt. I didn’t want to have any regrets about my surgery, so I did whatever I could possibly think of to help my body out.

One final PRK pre-op tip. Because you’re very light-sensitive after the surgery, many recommend wearing an eye-mask to block out the light. I chose not to, as I’d always gotten a little sweaty while wearing one, and that dampness makes a nice moist bacteria soup, which could only have increased the chance of infection. As a result, even while wearing two-pairs of sunglasses indoors (regular ones with the ‘over the glasses’ pair I was given by the clinic), and even with my eyes closed, the light was still unbearable. I thought I’d be okay, but I wound up needing my wife to tinfoil all the windows in the apartment, no doubt causing my neighbours to suspect I was growing something illicit. Knowing what I know now, I’d have definitely prepped the apartment with tinfoil before the surgery, as it was absolutely necessary.

Continued Reading

Here are my posts on PRK and laser eye surgery, continue reading or, feel free to join the discussion in the comments below!

Laser Eye Surgery Primer: Lasik vs PRK
Lasik vs PRK: What the Lasik Doctor Doesn’t Tell You
My Laser Eye Surgery, Part I: PRK Pre-Op Preparation (You are Here)
My Laser Eye Surgery, Part II: The PRK Operation
My Laser Eye Surgery, Part III: PRK Post-Op Recovery
Halos: A Likely Complication of PRK or Lasik
    

The post My Laser Eye Surgery, Part I: PRK Pre-Op Preparation appeared first on is this your homework?.

News of a potentially huge breakthrough in physics, that the Cosmic Speed Limit may have been violated, has taken the world by storm this past week. As a fan of science in general and physics especially, I am excited not only by the observations reported, but also by the fact that physics, of all things, is capturing the interest of the general population.

While we occasionally hear news reports on cosmology, updates on the age of the universe or beautiful glimpses at the jeweled treasures of our galaxy, and while the happenings at the LHC sometimes percolate up into the level of the general news, it is infrequent that these reports truly grab the attention and spark discussion among the wide population.

Yet the recent news that something has perhaps violated the ‘law’ that nothing can travel faster than light –a physical principle right up there with E=mc², one which every child has known since they sat upon their mother’s knee– has been lighting up internet forums, social networking news-feeds, and office lunchrooms.

With this article, I’ll try to shed some light (har!) on the recent developments, and hope to share a bit of my enthusiasm (and skepticism) of the news.

What happened?

The news has come that a group of scientists at CERN, the European Organization for Nuclear Research, have recorded observations where sub-atomic particles have been measured to travel faster than the speed of light. They fired neutrinos from Switzerland at a detector in Italy and clocked a time for the ~730km trip which was 60 nanoseconds (0.00000006 seconds) faster than light could have travelled that same distance in a vacuum (that will be important later).

Scientists say they have fired neutrinos below-ground, faster than the speed of light from a laboratory in Geneva, to a laboratory 545 miles away in Italy.

[Associated Press]

As expected, an observation such as this has been met with considerable skepticism. Indeed the group of scientists at CERN (not the same CERN team that is doing physics at the Large Hadron Collider) have spent the past two months reexamining their experiment, trying to find a flaw in it which would explain the results without violating c (the speed of light in a vacuum). So far they haven’t been successful, but they’re still not willing to go so far as to say these neutrinos have travelled faster than c. Instead they are asking for help from the physics community, asking for their colleagues around the world to try to replicate the experiment, and perhaps find any flaws in the experiment which would preserve c as the cosmic speed limit.

It’s important to realize the razor thin margin at which light speed was supposedly broken. The results point to a speed which caused the neutrinos to arrive 60 nanoseconds faster than expected, with a margin of error of 10 nanoseconds. The speed measured was just 0.002% faster than the exact value expected by all of modern physics. There are an extraordinary number of mundane explanations that could introduce such a tiny, tiny variance. For example, an error of only 18m in the calculation of the roughly 730km distance between the emitter and the detector would be sufficient to account for the faster than light claims.

Even if the distance between those two locations is known down to within 18m, there are a whole host of variables that come into play, each of which can affect the measured result. Not the least among these is the fact that neutrinos are a very tricky species. It is unfathomably hard to detect a neutrino. A neutrino will happily zoom through a light-year of lead with only a 50% chance of interacting, or ‘hitting’ anything. Experiments which deal with them have to make their measurements, not on individual particles as can be done with light, accelerated electrons/protons, etc, but rather they have to fire billions and billions of neutrinos at a detector before they can even hope to have one hit and be noticed. Some pretty hairy statistical analysis is then used to extrapolate what happened.

How is “c” different from “the speed of light”?

Depending on how often you peruse the science section of your news-aggregator of choice, you may somewhat frequently hear of events, particles, phenomena, etc that travel faster than the speed of light in a given medium (air, water, fibre-optic glass, etc). This could certainly cause confusion as to why this week’s news is any different. The confusion is caused by a bit of ambiguity in the language used in the reporting these various events.

The constant “c” is “the speed of light in a vacuum”. This is not the same as ‘the speed of light’ or ‘the speed that light travels’, because we know that light is often slowed from c by its medium.

The speed of light in a vacuum is approximately 1.079 billion km/h

Physics knows of and expects that light waves/photons can be slowed by the medium through which they travel. When light travels through air or water or glass, it is slowed from it’s ‘normal’ speed, c, by that material. We understand this physics very well, as it is necessary to explain how something as simple as a prism works (light of different energy/colours is slowed at different rates, resulting in a separation).

Some things can even move faster than light waves can move through a given medium, because they aren’t affected by that medium in the same way that light itself is. This physics is also very well understood, but even in these cases where things are traveling faster than light, nothing is travelling faster than c.

What’s so special about “c”?

What’s interesting about c is that it is a calculated constant which comes out of the math in Maxwell’s equations on electromagnetism. Indeed, it was the fact that the value for c is not dependent on physical measurements, that its value comes out of the equations themselves, that gave Einstein his lightbulb moment (har!), leading him to his theories of Special and General Relativity.

Einstein’s revelation was that, since the math dictates c, and since no matter where you are or how you’re moving, math will work the same way, then therefore light will always travel at c (when not slowed by a medium). Einstein’s brilliance was in how he interpreted the consequences of that basic principle.

Traveling faster than c simply breaks the math of Maxwell’s equations and the math upon which most of the past century’s physics has been built. Numerous predictions of physical reality have come solely out of the math contained in those equations. Some of these predictions, like those of relativity, at times can make the universe look like a funhouse mirror. Yet over and over, these mathematical predictions have been verified to occur in our physical reality via an incredible number of laboratory experiments, astronomical observations, and technological advances.

Why so skeptical?

Much of modern physics simply wouldn’t work if Maxwell’s equations and those derived from them weren’t able to stand up to the extremely rigorous poking, prodding, testing, and attempts to break them that have occurred over the past century as part of the progress we’ve made in just about every area of physics. Yet the idea that these neutrinos have travelled faster than c would mean that Maxwell’s equations are incorrect in a deeply fundamental way.

While we’re certain that we have a lot more to learn about physics on the grandest and smallest scales, it is difficult to believe how this bedrock of modern physics could be so marvelously predictive and accurate in describing the universe around us, while at the same time being completely wrong about c as the cosmic speed limit.

Faced with the results of one experiment, an experiment in which the particles were measured to travel so very, very close to exactly the figure of c we expect, even one in which the scientists have been so careful, skepticism is the natural reaction to those who think rationally and scientifically.

That said, it would be absolutely wonderful if this were true. Superluminal speeds would lead the way to a new area, perhaps even a new era, of physics and technology. It would hallmark the arrival of a vast amount of fundamentally new knowledge of how the universe works.

I’d be willing to bet a large amount that this result turns out to have a mundane explanation. Though, I would dearly love to lose that bet.    

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I’m going in for PRK Laser Eye Surgery in a few days, and true to character I’ve done more than my share of research. I’ve learned quite a bit, and I’d like to share some of it with you. [Edit: Be sure to check out my follow-up account of the surgery: My Laser Eye Surgery, Part I: PRK Pre-Op Preparation and the forthcoming Part II] Unfortunately I don’t have the time to give this topic the full attention it deserves, so this post will be a primer on Laser Eye Surgery and especially why I think Lasik and other corneal flap-based methods are ill-advised compared to PRK and other surface ablation methods. See this as an advisement to seek further information.

I don’t want this to be a ‘scare’ post, but I’ve spoken with many people recently who really didn’t know much about the laser eye surgery they had done, especially the complications specific to Lasik. I spoke with one man who had Lasik done, but he didn’t know that he had a flap cut in his cornea! Indeed he insisted that there was no flap. We did establish that he had Lasik, he had no pain and good vision the next day (definitely Lasik), but he was adamant that there was no flap to worry about. That was scary to me, because it means that, whether or not he was actually told about the procedure or about the flap risks, he certainly never understood the procedure, the risks, or the care you have to take with the flap.

In my experience with my own research of the available information on Lasik and PRK over the past 10+ years, and especially in the past several weeks, the practitioners of both procedures largely (or completely) gloss over the risks, and most patients make uninformed decisions. If people go in with eyes-open (ahem), then it’s their choice, but I hate to see people getting the wool pulled over their eyes (apologies again for the punnery).

If you’ve informed yourself and want Lasik, I’d suggest stopping here. However, if you’re unsure of the differences between the procedures, or if you are unsure of the risks of the procedures, you may want to continue reading. Please don’t take my word for this. Please use this as a jumping-off point for your own research.

On Irony and Selection Bias

First, an aside on irony. I’ve done my research, I understand the risks of PRK and Lasik. I have my PRK scheduled for a few days from now (July 20, 2011) and I understand and accept that I could be one of the edge cases that have serious or merely undesirable side effects (*knock wood*). I understand that I could know 1,000 people that are perfectly happy with Lasik, but I also know that anecdotal evidence is relatively worthless.

Whatever my outcome, whatever the outcome of your cousin, your co-worker, or everybody you know, the dice are being rolled with each procedure, and each procedure has its different risks. These risks exist and must be looked at on aggregate for each procedure, hopefully before you go under the laser.

Lasik vs PRK

Both PRK and Lasik have somewhat similar risks of undesirable side effects to your vision (stars, halos, dryness, etc), some suggest PRK has somewhat less of them (especially chronic dryness), but it seems to be debatable, and often it comes down to individual reaction to the procedures. You can make choices about your individual procedure (either Lasik or PRK) that will mitigate those risks, such as getting the better lasers, the latest techniques, etc (please inform yourself), but the risks will always remain.

I’m willing to take those risks (with either surgery), but I’d not take on the flap risks that are specific to Lasik (even the all-laser Lasik).

While PRK and other ‘surface ablation’ methods, make the correction on the surface of the cornea, Lasik methods cut a flap part-way through the cornea itself (about 15-20% of the way through). This creation of the flap introduces a host of side-effects and complications that just don’t apply to the surface ablation treatments such as PRK.

Note that same lasers can be used to make the correction in either procedure, though there are some important differences between lasers, eye tracking, algorithms, etc, which play a somewhat important role in mitigating those ‘minor’ quality of vision side-effects.

For me PRK is the better choice, actually the only choice I’d consider. You can find a good overview of the differences between PRK and Lasik here.

With Lasik, the flap never really heals, and most Lasik providers will feed you the oft-quoted maxim that “after 2 years when it heals to its maximum, any trauma strong enough to dislodge the flap would be strong enough to injure the eye”. The problem is that this doesn’t seem to be true.

You can find many Ophthalmologist accounts of flaps that have been dislodged through fairly incidental contact (your own finger, tennis ball, tree branch, etc). Sure the risks are low that this happens, but the flap never actually heals. Pretty much only the skin layer overtop actually heals; many ophthalmologists report that the lasik flap can be very easily lifted open many years after the procedure. Those considering Lasik would be well served by reading more about flap complications (be mindful that while they are rare, they are very real).

The Lasik method of cutting a corneal flap not only seems dodgy from the outset, but is starting to show some long-term side-effects. While laser eye surgery has been around for several decades, Lasik and it’s flap-method was FDA approved in 1998. Somewhat rare, but not all that uncommon, issues have been found with ectasia (corneal bulging, due to comprised cornea integrity), epithelial in-growth under the flap, striations (wrinkles) in the flap with or without trauma, and partial flap dislocation, all many years down the road.

Lasik also has a higher need for re-treatment, but ironically the risks of Lasik compound on multiple procedures. This makes re-treatment much more difficult and much more risky with Lasik than the no-flap methods of surface ablation, like PRK. With PRK the need for re-treatment has been reported to be considerably lower, but in the cases where it is necessary (or where the vision needs a touch-up years down the road), that re-treatment is no riskier than the original treatment.

Conclusions

Laser eye surgery isn’t without its risks. I’ve weighed those risks, and am going to do PRK. The only real benefit of Lasik is the fast recovery. From all I’ve seen, Lasik is the very definition of a ‘quick fix’. If Lasik was the only method available, I would stick with glasses and contacts.

I truly hope this helps those who may otherwise go uninformed, encouraging them to take pause and research for themselves the reality of the various laser eye procedures.

Continued Reading

Here are my posts on PRK and laser eye surgery, continue reading or, feel free to join the discussion in the comments below!

Laser Eye Surgery Primer: Lasik vs PRK (You are Here)
Lasik vs PRK: What the Lasik Doctor Doesn’t Tell You
My Laser Eye Surgery, Part I: PRK Pre-Op Preparation
My Laser Eye Surgery, Part II: The PRK Operation
My Laser Eye Surgery, Part III: PRK Post-Op Recovery
Halos: A Likely Complication of PRK or Lasik
    

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