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My Laser Eye Surgery, Part I: PRK Pre-Op Preparation

October 3, 2012 |  by  |  Science

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.

A huge portion of the outcome of PRK surgery relies on the decisions made during the post-op after-care period.

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.

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.

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

More Information


  1. Very timely post! We share the road less traveled. I have been interested in getting my vision corrected since the days of radial keratotomy. I recently came to the same conclusion that you did regarding the benefits of PRK over Lasik. I am now contemplating the PRK procedure again and will likely pull the trigger. Your checklist will prove valuable in my decision.

    One question I have for you is: when the epithelium is pealed away did your doctor use an alcohol solution, other solution or a brush method? Some say the alcohol method creates subsequent hazing in some patients. Do you know if your epithelium was removed or simply pushed aside during the laser treatment?

    Looking forward to your next update.

    • With PRK, the epithelium is removed completely after an alcohol bath. This is the primary difference between PRK, Lasek, and Epi-Lasik (none to be confused with Lasik, which uses a cornea-flap, and is not something I’d have ever considered).

      Lasek and Epi-Lasek are relative newcomers, attempting to combine the convenience of Lasik with the safety of PRK both make a flap from the epithelium, which is then replaced after correction. Lasek (and sometimes Epi-Lasik) also uses an alcohol bath to loosen the epithelium.

      I haven’t studied the skin-only flap based methods of Lasek and Epi-Lasek as thoroughly as I had studied Lasik and PRK, but they do seem to have all of the benefits of the surface ablation procedure, PRK, without the very serious corneal-flap based complications of Lasik.

      • Your thoughts are most welcome.. I’ve got 7mm and 8mm pupils. My concern is knowing the laser’s ablation zone can handle that area – and also – the corneal thickness required to ablate to -6.25 diopter. Looking at a clinic using Amaris 750s. Can’t find Internet specs for the Amaris. Thx!

        • Victor if you are still there – the VISX star 4 IR can adjust to an optical zone of 7mm with ease using the customvue design station; I do it all the time. The STAR S4 IR is the best FDA approved laser for myopia, the allegretto is the best for hyperopia.The thing is that the wider the ablation zone the more tissue is removed. With PRK instead of LASIK you have a lot more tissue to work with so it is less of a concern but they may use a short mitomycin treatment to reduce haze risk that rises with deeper ablations.

          Trinidad.Eddie – I have not used the schwind laser (amaris is made by schwind – german) because it isn’t FDA approved and probably won’t be because they don’t want to spend the money to get it approved. At last year’s ASCRS convention I spent a couple hours talking to the scientists at the schwind exhibit – it has some advantages over all the US lasers such as capability to do transepithelial ablation PRK, 500 spots per second capability and a really fast tracker. I believe it is a good option out of the USA.

      • Thanks for the info, I live in Vancover too, wondering which two clinics did you consider, and which did you go to? I can email if you don’t want to say in pulic, would be tremendous help, thanks.

  2. Have you written about your experience during the surgery and the post op phase? I would love your take on it. Your article is so great and answers a great deal of the questions I had.

  3. Mr Temple: Thanks very much for this well written and informative post. I think it’s the most comprehensive I’ve seen and you’ve alerted me to issues I hadn’t considered. I’ve recently decided on PRK due to the risks with other procedures though I’m still very nervous about the recovery. I know you didn’t want to recommend a clinic in a public setting, but I wonder if you would via email. I live in Delta and had been considering Coal Harbour after ruling out a few other clinics.

    Thanks. Cris

  4. I can’t thank you enough for all this fantastic information! I too considered Lasik before fully understanding the risks involved. Like Cris above, I am considering having PRK done at Coal Harbour in Vancouver and would really appreciate your thoughts on them as well. Please email me if you feel it would be a more appropriate venue. Thanks again!

  5. Mr. Temple,

    I was curious as to what laser was used for your PRK surgery?

    When you stated that your pupils were “slightly larger”, can you disclose what they ended up being dilated?

    For example, mine are 7mm. The one and only local Lasik/PRK facility near me has the Visx Star S4 CustomVue. I see that the Optical Zone is 6mm (assuming “Optical Zone” is the same thing as the “Non-Tapered Zone”?) and the Treatment Zone is 9mm (assuming the “Treatment Zone” is the same as the “Tapered Zone”?).

    Would you think that this laser may not be the best candidate based on my pupil size?

    I found another clinic some distance away that also has the Visx Star S4, but they also have the WaveLight Allegretto Wave. The Optical Zone appears larger at 4.5-8.0mm and the Treatment Zone is 5.2-8.7mm. On the surface, this WaveLIght seems like a more suitable candidate considering my pupil size?


  6. There’s misinformation in your post.

    First, doctors never overcorrect you. You do not adjust your level of correction with your steroid drops. Steroid drops are to mute the wound response and reduce inflammation of the
    cornea. The greater the correction the greater the wound response, the greater the frequency to use steroid drops…

    • Steve, I have to say that I disagree with you at least on your first comment. I just had a consultation with a clinic last week, and they told me that my eyesight had been overcorrected. Apparently corrected vision better than 20/20 is considered to be an overcorrection (which makes sense to me, since 20/20 is considered to be “perfect.) I can currently see 20/15 in each eye, and just about 20/10 together, with my contacts or with my glasses. (I’m not quite sure how that works, but that’s what the chart said when I could read it.) The doctor had mentioned that one of her concerns is that the goal with the surgery is to get my eyesight to 20/20, and anything better is kind of like a bonus. Since I am used to seeing better than 20/20, she’s concerned that I won’t be happy with my results if I cannot see things as crisply as I do now. Just something for people to consider… know your current prescription and your corrected vision!

      I’m still weighing my options, and hoping to pull the trigger on a procedure within the next month or so. This is a great article and I have to thank you for posting it Mr. Temple!

  7. Overcorrection does not relate to your visual acuity but rather to your glasses perscription and it happens all the time, although usually in small amounts. Say you are a nearsighted person with a glasses prescription to correct your vision of -5.0 diopters. You have laser vision correction and end up + 0.5 diopters. That would be an effect from the surgery of -5.5 diopters, hence an overcorrection of .5 more than you need. A younger person could just focus (accomodate) their lens the extra +.5 and see just fine. The acuity depends more on retinal capability to see fine images, aberrations in the optical system etc.

    We can use steroids to control the amount of the corneal regression healing and remodelling just a little bit – especially in PRK vice LASIK. Undercorrected – less steroids – overcorrected – more or longer use of steroids.

    Thirdly they tell you the visual results are about the same and that is true, and they tell you that the healing time and discomfort is more with PRK which is also true, but they often don’t tell you that PRK is quite a bit SAFER than LASIK. Maybe this is because the PRK is more of a hassle for the doc.

    Hope that helps

  8. Hi there. I just had my PRK last Mon, and it’s still in healing process. I took off the bandage contact already, but the vision is not perfect. I see better far away objects with my left eye and close objects with my right. They were never the same. I did the drops according to what the doc told me, but they didn’t change anything during the first 3 sessions like your doc told you to reduce the drops. I’m a little worried whether I will get there…

    • Hi Sophia,

      I’m considering PRK and came across your comment. It’s been a few years but I’m curious – how are you doing now?

  9. Tremendously helpful article, looking forward to the follow up. I’d have never considered the post-op care outsourcing to be a problem without reading this. Also, a great checklist of questions. I’m now convinced that speaking to any surgeons without being armed without a print out of these questions is foolish. Thanks! Were there any additional questions you asked of the surgeons?

  10. What clinic did you decide to go with?

  11. Yes! Very informative and objective information. I’m wondering if you can email me the clinic and laser tech that you opted for, as I want to try to find a comparible clinic in central Canada. Thanks for this!

    • I picked Dr Jeffrey Machat of Crystal Clear Vision, Toronto, for two primary reasons. (1) Dr Machat’s experience dates from the early days of TLC. (2) Dr Machat has likely the most advanced laser available, Schwind Amaris 750. Given my large 8mm pupils and -6.25 eyes, the laser tech is as important as the skill of the surgeon.

  12. Great help!!! thank you.

  13. Hi! Your Lasix vs PRK was so helpful and your list of questions was great. I feel pretty much blind when I wake up in the morning and want to see better. My eyes are -5.0 and my corneas are too thin for Lasix! I started researching and came across your stuff and I am so glad I did. Would you be able to help me out? Basically, I need to know if you see anything disturbing.
    I believe I understand most of the answers to the questions, but wanted a “pro” to take a second look.
    The two questions I don’t like the answers to are #5 because it sounds like my eye has to do a lot of work and #6 because I heal so poorly. It does not appear that they customize the after care.
    Am I reading that correctly? Is there anything that you see that is alarming?
    Below are the questions (you provided) and answers (from office)

    1. What is my dilated pupil size?

    - How big is the actual correction area (not including the blend area)? The optical zone the doctor chooses is customized to each patient; it can vary from 6.0-7.0 mm depending upon pupil size, correction, eye size & shape, and thickness of the cornea

    - Is it bigger than pupil at night?

    Your pupil varies in different illumination levels, an individual’s pupil can range from 4-5 mm in darkness (or smaller, again everyone is different) to 6-8 mm in darkness (rarely do we see a 8.5-9 naturally dilating pupil) – there are different levels of “darkness”. For example, your pupil size can vary depending upon how bright your illumination panel is in the car, how light the road is you are traveling upon. If it’s a dark road with no streetlights and your dashboard is not casting off a bright light, your pupil size can be larger than if you were on a highway or two lane road with many streetlights and oncoming cars. If you are at home in a room with only one lamp on, it depends on how close you are to the lamp, how much light it is casting, if the TV is on, if you have an eReader or notebook in your lap, etc., etc. The size of the optical zone is limited by FDA approval, the largest optical zone choice for the Zyoptix platform is 7 mm. the doctor actually drove around at night on both types of roads mentioned above with a device which measured different levels of illumination and did a mini-study of his own of how the pupil responded. It’s important to know that each patient responds differently with regards to how large their pupil becomes in different illumination levels – both during the day & the night.

    2. What laser system in being used for:

    -mapping? Bausch & Lomb Zyoptix Dual Workstation for topography & aberrometry

    -tracking? Bausch & Lomb Advance Controlled Eyetracking

    -correcting my eyes? Bausch & Lomb 217z100 excimer laser

    -What version of each component is used? There are too many components of this complex system to list each version used; there are hundreds of components which make up the diagnostic and laser system from software to hardware

    -Are they the latest version? Every software version is the latest upgrade to the platform we use – there have been no upgrades to this system since 2011 software-wise which had an effect on treatment programming or treatment. All components have preventative maintenance performed by company specification every 6 months at least. The laser is calibrated prior to every patient, often when the patient is in the room, right before the patient lies down on the table.

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

    There is no such thing as a non-tapered treatment zone with our system – there is an optical zone and a treatment zone, the treatment zone includes the blend zone, which is a tangential linear blend. The optical zone, which is fully corrected, is listed above and varies according to factors also listed and what is programmed for each individual.

    -What is the size of the tapered transition zone of the procedure? This varies and is specifically dependent upon optical zone selection as well as higher order aberration correction, astigmatism correction and myopic or hyperopic correction, in addition to treatment mode

    4. Is a custom ‘map’ of my prescription measured (WaveFront)? Yes

    -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? There is no “preset” correction we use, that is a feature of the Allegretto system, which is called “wavefront optimized”. This type of wavefront optimized treatment is not a “custom” treatment. With our system, wavefront maps of each eye are used to customize each eye’s treatment, in addition, a specific nomogram customized to the doctor is also used, an advanced nomogram is applied to optimize the outcome based upon specific aberrations present in each eye, as well as a personal nomogram adjustment then used based upon several factors which Dr. MacRae has fine-tuned over the years in his experience. So in reality, the treatment is customized in various ways, including the individual aberrations measured by aberrometry that are present and beyond solely that factor.

    5. What eye tracking system is used? For example: Do I have to do all the work or do you have eye tracker?

    You have to look where directed in order to be aligned correctly before beginning treatment; once you are aligned correctly, the iris tracker has tolerances of movement before blocking the pulse of the laser if outside of tolerance range; the doctor also perfects centration tighter than tolerance range throughout the case.

    -Does it track the inside of the iris, or the outside of the iris? It is an iris tracker and uses thousands of data points to track the iris. There are no other landmarks to track outside of the iris. The iris is more unique than a fingerprint.

    -How many times a second does it track? You could be referring to two different things here, so I’m not sure I understand your question. Milliseconds are what eye trackers typically work within – this tracker can track movement up to 25 microns per millisecond; a saccadic eye typically moves 24 microns/millisecond, and we’ve actually found that it does keep up with saccadic eye movements. The hertz rate of the camera is different – it takes 240 pictures/second, which is 2x plus the speed of the laser

    -Does it track in 3D or 2D? It is 5 dimensional tracking actually – x, y z, cyclotorsion, and intraoperative rotational. There are also another feature of the tracker used with regards to pupil centration, so you could say it is 6D tracking, but my personal opinion is that’s a stretch J, others would disagree. To my knowledge, no other laser in the US accounts for intraoperative eye rotational tracking. This is important, as when treating and fine sculpting, it is necessary to account for every movement the eye makes in every direction, which includes rotationally. The B+L system is the only one that I know of in the US that can actually measure each pulse’s placement onto the cornea, in addition to proving that x, y, z and introp rotation movement is occurring and is being accounted for.

    6. Is the post-op medication custom-tailored to me during each visit? According to your healing, the medication is adjusted appropriately at day 1 and you are given specific instructions on instilling the medications for a specific number of days and are instructed to return based upon your healing.
    From my reading, it seems the first 3-5 days post op changes and alterations in medicines make a huge difference. I’m curious as to where you are finding this information. I’ve worked with hundreds of surgeons, and unless there are other medical conditions present which directly affect the cornea, there is a standard regimen followed across the board with regards to the anti-inflammatory, anti-biotic, and artificial tears application and usage, which leads to proper healing and re-epithelialization of the cornea. There is also a bandage contact lens which is placed on the cornea after PRK which must remain on the eye for a specific length of time in conjunction with the medication regimen. If a surgeon is altering your medications quite often in 3-5 days, in my opinion, something else may be going on. If I were to choose a fellow to perform the surgery for monetary purposes, do you check on me after surgery with the fellow and check on the changes and or alterations the fellow makes to my medicines? The doctor will take a look at your eyes and discuss your eyes with the corneal fellow at each visit.

    7. Finally, I heal horribly! Every surgery I have ever had I heal slowly and get scars. I even keloid after each surgery. Would you suggest doing anything before surgery to help my body heal? Would you suggest Mytomycin-C for me?

    Being a keloid former is important to know; there have been studies conducted with regards to keloid formation and refractive surgery, and the doctor has performed surgery on such patients. Specific questions about being a keloid former (if there are more) would need to be addressed one-on-one. The doctor uses Mitomycin-C on most PRK patients based upon his personal treatment practices, techniques, and years of experience, as well as his standard of care.

    ***She also asked where I got all this information and stated that only scientists ask this many questions:-) lol

    Thank you for your help.

    • I am certainly not a “pro” or an expert, but I do have the following concerns/questions about these answers:

      Q1: It didn’t seem they’ve given you the measurement for your eye (maybe you haven’t visited yet). If you don’t know your dilated pupil size (at the appropriate darkness/adjustment level), you can’t compare it to the area of treatment.

      Q3: It reads like they’re dancing around semantics here. “There is no such thing as a non-tapered treatment zone with our system” but there is a ‘blend zone’. See what I mean? What they don’t tell you, what you need to know, is how big the untapered/unblended treatment zone is. This is the only zone that actually has your ‘prescription’. Light coming into blend/taper zones will be fuzzy. Guaranteed. This can lead to haloing. Depending on your pupil size, where the taper/blend zone may not matter, then again, it may. They didn’t actually tell you what the non-blend/taper zone is (they did say the max the system could do, but that’s not necessarily the same), nor did they tell you your pupil size, so you don’t have the information necessary to make an informed risk assessment.

      Q4: Short answer, your wavefront map isn’t used by the Alegretto’s “wavefront-optimized” system. It’s using what I call preset maps for the correction. This is corroborated many places, for example (

      “The Allegreto laser company used other manufacturer’s wavefront devices to measure the wavefronts of many people before and after Allegreto laser treatments and calculated the average spherical aberration induced for several amounts of Myopia. They then constructed a computer program to add extra peripheral pulses for given amounts of Myopia. If your cornea does not have the average spherical aberration that the Allegreto laser has in its program data base then you will be either under corrected or over corrected in spherical aberration.”

      Also: “The Allegretto laser adds peripheral pulses based on the amount of myopia you have and does not take into account your preexisting spherical aberration you already have. This is a one size fits all approach. There is a significant difference between “wavefront-guided” and “wavefront-optimized.” It is important to know what laser is going to be used on your eye.”

      Q6: This would be a deal-breaker for me. They’re spinning the fact that they don’t make the adjustments and just stick to the “standard regimen followed across the board”. People are very different with regards to their healing and re-epithelialization. You yourself point out that you’ve historically been an edge case in healing. Do you want a “standard regimen followed across the board” or do you want custom care by repeat examinations during the critical phase of re-epithelialization?

      From what you posted, my gut would say keep looking.

      Good luck!

  14. I can not thank you enough!!!!! I wish I lived near you so I could go to the same doctor!

  15. I do believe I am a younger one of the bunch of people that want to undergo this specific PRK surgery. I recently turned 18 and have avoided contacts and glasses ever since my vision got too bad to see that I had to go get an eye check when I was 13. Then my vision was around -1.75 and now it’s like -2.50 to -2.75 on one of my eyes I believe. It’s really weird because I saw an NHS eye doctor in London and they said that I was -3.00 on both eyes but at this clinic back home I am -2.50 on one eye and on the other -2.75 as I mentioned, although can’t remember exactly which one is which because as mentioned I try and avoid glasses as much as possible because due to my way of life I do not like wearing them, it’s not comfortable and my eyes seem to be too sensitive for contacts and I’m too scared to get infections and keep them in all day and keep taking them out. I have tried wearing them maybe a few times less than 5 and hated the feeling. I will wait 6 months if I have to see because I do wanna see perfectly with no need for stupid glasses or contacts when I live in the 21st century where such procedures are available.

    I am going to go to my father’s friend’s place where they are pro and have won numerous awards as well as they’re going to monitor my process well and make sure everything turns out ok. The price is also much less than what I’ve seen here but that’s just because of a promotion going on and location of this place. I will not mention where it is because I feel like it’s personal.

    But I wanted to thank you for encouraging me to go ahead with this process and see the world for what it is without the help of artificial products. This place has the newest technology and they will make sure to answer all my questions and everything because luckily I know the owner and he will have to make sure that my questions are answered because I’m still a child. I also forgot to mention that I have mild astigmatism but I forgot the amount, but it’s nothing major.

    I hope everything goes well for me and I am fortunate enought to have a parent who knows a good place and has the means but as I mentioned the price is very decent to pay for this and I will forever be grateful. I do sports a lot and move around and will not opt for LASIK as I do not want my eye being cut and complications to occur because of my lifestyle full of swimming and moving around.

    Thank you so much Sir for such encouraging articles and I wish you all the best with your eyesight :)

    PS. I apologize for my English if there are any mistakes. I am rather fluent in it but still not a complete fluent speaker or not old enough to have such a wild range of vocabulary as you and also am not that smart lol xD you sir are a genius! :D

  16. I apologize but I have one question as well…did your surgery doctor order your post-op plan or just a whole team of other doctors because this guy that has to do my surgery is constantly away and only comes in maybe once a month to do a couple of LASIK and other types of surgeries as well as PRK maybe stays a week and goes back to his country…I’m scared of getting a generalized treatment because these are my eyes and yeah…does the surgery guy have to keep track of your healing process or is it ok if possibly it’s not included in the price but they as in other doctors as well keep track of everything and still custom make it to your healing process? It seems this place doesn’t offer eyedrops and you have to get them yourself…I’m a bit scared now despite the numerous awards won because they do more LASIK surgeries I think…

    • Hi Emma. Where I got mine done, the surgeon who performed the surgery was not the doctor who performed the after-care checkups.

      However, they were both full-time practitioners at the same clinic, which had several surgeons and several ophthalmologists doing the after-care. I was confident that the doctors doing the after-care had experience of many thousands of surgeries performed in-house.

      The concern I have with what you wrote is that is sounds like the surgeon does not spend much time at that clinic, which makes me wonder how much experience that clinic has with PRK surgeries.

      I’d definitely check this out. Find out how many PRKs the clinic performs a year (which may be different than the number the doctor performs). That will help you decide whether you feel they are experienced enough to go with them.

      Now it might be that the doctor is semi-retired, or that he’s one of several surgeons at the clinic, and the clinic itself has many, many thousands of successful surgeries. If that’s the case, I’d be far less concerned.

      Good luck, and keep us posted!

      PS: Your English is terrific!

      • I see indeed I will ask them as much as I can although I do remember the owner stating that they constantly do all kinds of eye surgeries like different kinds and as you said it’s about the machines and experience rather than cost and other factors like a high tech office or something completely useless in the case of surgeries. I see yeah it seems my concern for the surgeon doing the after care was a bit much but he does have a lot of work going on back and forth between different countries around Europe but still comes here often and stays for longer than I expected. I was ensured that there is a good team of doctors that do the after care and that it’s not up to the surgeon to do it but am happy to know that they hand you the eye drops and everything which I asked them. I will ask them a few more questions about my concerns but for now I feel confident about the operation, which will be in a month’s time from now and hope everything turns out well :)

        Thank you for the feedback and will keep you posted :D

      • Hi Mr. Temple,

        I’ve just been informed by a surgeon that he would recommend PRK for my eyes, and I’m therefore thrilled to read your post! Thank you for sharing your research … be assured that I am doing additional reading, and I am going to another clinic for a second opinion and more information. I gather you went to London Eye Centre? Are you at liberty to say which surgeon performed your procedure? I am currently leaning towards Dr. Maerov at the New Westminster branch. Thanks.


        • Hi Janice,

          I tried emailing you, but the address bounced. If you contact me via the mail link at the top of the page, I’ll let you know where I went and who did my zap-zap.

          • Thanks for all the great info. May I ask which two clinics you considered and where you got your surgery done ? many thanks for your kind feedback in advance, cheers

          • Thanks for all the great info.
            I am note sure if my question or comment went through so I wish to submit my comment again, can you please kindly advise which two clinics you considered and where you did your surgery please ? many thanks, cheers

  17. Ah and yes they have done numerous PRK surgeries so asking them that as you said and knowing they’ve done many other successful ones I feel a lot better about the process. Apologies for forgetting to type this in my first reply.

  18. Hi Craig,


    I’m not sure whether Intralase was an option for you when you had your surgery done? I was hoping you have an opinion on it, as it’s an option and a consideration for me, mainly due to recovery time … I’m OLD! I’ll do some further research on my own as well.

    Thanks for ALL your input on your website and helping so many people, but ESPECIALLY for taking the time to respond to individuals! You’re amazing.


    • As far as I understand Intralase merely distinguishes between how the epithelial or cornea (or both) are cut, where intralase uses a laser and the standard uses a blade.

      All the concerns with cornea flaps still exist, though they are mitigated somewhat as intralase increases the accuracy of the cornea-flap cut. This helps ensure the maximum amount of cornea is left intact. *However* I’m still of the philosophy that no amount of cornea-flap is healthy or advisable, so I’d steer well clear of Intralase Lasik too.

      There is some complication in the industry of course. The Lasik ‘brand’ has huge sales power, but more and more doctors are going to the better alternatives that don’t involve a *cornea* flap. Things like PRK, where the epithelial (skin) layer is removed, but no cornea flap is cut, then there’s Lasek (note the E), in which a flap is made with the epithelial, but not the cornea (essentially PRK with a skin flap), etc. There’s loads of similarly sounding procedures, so it’s tough to compare without getting all the details.

      I have no idea if it’s the case, but if there’s an Intralase PRK/Lasek (there’s that all-important no-cornea-flap E again!), that might be the best of both worlds. Lasek (not Lasik) eliminates the cornea-flap, so doesn’t have nearly the safety concerns of Lasik. Really the only flap is the epithelial layer (which is removed and regrown in PRK). The apparent benefit is that the epithelial layer doesn’t have to completely regrow, so there’s a much quicker recovery (similar to Lasik). I understand there are potential minor flap issues (dislodging, wrinkling, infection, scarring, etc) with the Lasek skin-only flap, but as I understand just about the worst case scenario is that they decide to take the epithelial flap right off, essentially turning your Lasek (not lasik!) into a PRK.

      Confused? :)

      • THANK YOU for your opinion, which, by the way, I value highly and appreciate significantly.

        You’re a wealth of unbiased information, and I can’t thank you enough. Perhaps I should stick with PRK. I had read about LasEk, and discovered that if there are problems with the epithelial flap, it can be removed … so in essence, I guess, it becomes PRK.

        You’re absolutely right … your brilliant idea of an “Intralase/PRK/Lasek” would solve many, many problems.

        Thanks again, Craig, for your openness and dedication to help others by sharing your research and experiences. You’ve certainly helped me tremendously!

  19. Hey folks,

    I dusted off the nearly-complete account of my surgery and finally posted it. Here’s the long-awaited entry:

    My Laser Eye Surgery, Part II: The PRK Operation

  20. Hi,
    I am scheduled for PRK surgery next week Dr. Crews from Crews Laser Center in Vancouver, WA. Ironically your blog has links to his website. I have been referred to him from a couple people and feel good about my decision. So I’m curious if you choose to allow the link to his website on you website because you know that he is a good Dr/surgeon, or if its just there randomly. Thanks.

  21. Hi!

    Thanks for the wealth of information! It was great to read up on your procedure. I went for a consultation this morning at the London Eye Clinic in North Vancouver, and agree that it is important that follow ups are done by the same establishment.

    Would it be possible to email me to let me know which Surgeon carried out the procedure for you, and which location you went to?

    Thank you!

  22. Great article and comments. I’ve just canceled my LASIK surgery as I was not very comfortable with the process. Especially after reading one of the spice girls almost went blind. Your comments just reinforced even more what I had learned.

    The only thing I am confused is that it seems that in PRK they are still making a flap? see:

    Is it just a thinner flap that can be discarded and it will grow again?
    I am researching now about LASEK and no touch PRK (whatever that is)


    • PRK (including the one in the video you linked) never has a corneal flap.

      What you saw is the epithelial layer removed. This is the skin covering of the cornea. The actual laser correction is applied to the surface of the cornea. After being completely removed, the epithelium takes several days to grow back (almost a week). This is why PRK recovery is much more uncomfortable (read that as painful) than PRK. The skin is removed, and has to grow back. Do that anywhere and it’s going to be raw and sore. Even after the first 5 days or so, when your epithelium has grown back, it’s still fresh and new, a bit swollen. It can take a couple/few weeks (sometimes more) before the ghosting issues from having a slightly swollen skin layer over your eye resolve themselves. Eventually the epithelium grows back to basically good-as-new state, and any scarring from the healing of the cut area is much wider than your pupil/correction zone, so any epithelial scarring you may have at the cut line won’t ever affect your vision (unlike lasik, where the cornea flap cut, and thus the cut through the epithelium is much smaller).

      In Lasik, a horizontal cut is made into the cornea itself (disturbing very little of the epithelium), the laser correction is made mid-cornea, and the flap is closed over (though as you might imagine, the two parts don’t really create a perfect seal as the base of the cornea has been reshaped, while the flap is still flat (flat-ish) from the cut. Lots of problems with a corneal flap, as the cornea never heals. The epithelial layer heals itself, just as with PRK (though there can be more scarring of the epithelium after Lasik, or at least more scarring within the pupil area, as the flap is smaller than the ring of epithelium removed during PRK). You’re forever left with your cornea flap held together by that thin little piece of epithelial skin. Which is why you’ll read reports of corneal flap dislodgement many, many years after surgery (and sometimes after impacts or accidents that an eye with an uncompromised cornea would have handled far better). Also, since Lasik’s cut-line of the epithelium is right at the spot of the cornea cut, you can also get issues where the epithelial scarring/healing actually grows into the cornea flap, causing complications beyond simple vision issues.

      • I forgot to mention: The newer PRK variants Lasek (note the e) and epi-Lasik are both cornea-surface treatments like PRK. In these, there is no cut into or flap made in the cornea, but there is a flap made in the epithelium (skin layer). There are minor complications with this epithelium flap, but much, MUCH less serious than the corneal-flap in Lasik. Basically if the epithelium flap in Lasek or epi-Lasik goes screwy, it’s simply removed, which turns the surgery into a de-facto PRK.

        The benefits of the epithelium flap can reduce the recovery time significantly, and make it as comfortable (pain free) as Lasik with its corneal flap.

        In 2011, when I did my surgery Lasek and epi-Lasik were fairly new, and I went with the tried an true method where the epithelium is removed entirely. If I were looking into my surgery today, I might very well have chosen Lasek or epi-Lasik over PRK, but I would never do a Lasik cornea flap, even if you paid me.

        Lots more info here:

        • Mr Temple

          Did the dr use MMC in your PRK procedure? I was reading this article:

          and man PRK looks as bad as LASIK. I guess in the end it is all gambling and we should be prepared for any bad outcome.

          Thank you

        • Mr. Temple

          It would be great if you wrote also about TransPRK / no touch PRK which uses the SCHWIND AMARIS laser (not used in USA yet). Are there advantages of using this laser? doesn’t it also remove the epithelial layer?

          Thank you sir

        • All your write-ups are great in that it’s very informative. I considered eye surgery in 2012 and now revisiting in 2016. Up-to-date I’ve been consulted as a great candidate for intraLasik using Custom Vue. You’ve reminded me that research must be thoroughly done and I have much reading to do. Definitely asking the above questions I didn’t ask for my recent consult and will get another consult with questions prepped in advance!

          • I had PRK in February 2014 in Ohio USA. I was not a candidate for LASIK . I had 20/15 vision within 4-5 days after surgery. While the 5 day recovery was pretty rough I am very pleased with my results almost 3 years later. I never had any problems with halos or poor night vision. My husband had the same surgery and healed quicker and it was because he took fish oil . You will wonder what the hell you did after day 2 (lol) – light sensitivity was out of control and your eyes feel like they have sand in them! I had to go to the doctor everyday for 4 days and read the chart which was almost impossible because of the sensitivity! On the 5th day it was like someone flipped a switch and my eyes felt much better and vision was unbelievable! By the way, my surgeon did all of my follow up.

  23. Thanks for sharing your thoughts about follow up care. Regards

  24. Hi Mr. Temple!
    Sorry to bother you… I am looking into laser eye surgery and found your posts very interesting. Just a quick question: when you wrote that your dilated pupil size is slightly wider than the treatment zone, how much exactly is that?
    I’m asking because I just did a visit a few days ago and my dilated pupil size is 6.4 mm, while the treatment zones of the lasers I am considering seem to be just 6.0 mm. Do you have any idea if this will cause problems in dim light or is the difference small enough to cause ‘problems’ only in pure darkness (which basically never happens) ?
    Thanks in advance for your answer, looking forward to hearing your reply!

    • Hmm, not really sure.

      One thing that I do know is my dilated pupil size was taken in a room that was not super-dark (and was done without drops). If that’s the same case with yours then you’ll have issues even when it’s not ‘absolutely dark’.

      Also, a circle of diameter 6.4mm has 13.8% more area than a circle of 6.0mm diameter. So, that’s a fair bit more light that can enter the eye. Even if that 6.0mm zone was fully corrected (and did not include taper), I’d imagine you’ll get some haloing at night.

      For me, as I think I mentioned, I notice the halos when driving at night in the country where it’s darker and fewer light sources, but not in the city where there is more ambient light. In fact, since I moved to the countryside, I notice that I can play with the halos (lights reflecting off cat-eye reflectors, etc). I can turn my car overhead/reading light on and watch the halos disappear (moving in concert with the pupil contracting). I can do this too when looking at the stars. The halos aren’t disturbing enough to keep a light on in the car (really, they’re much fainter than the image most of your corrected eye is getting. But of course I’d rather they weren’t there. If it came down to the decision of having the halos I have now (in rare cases) or not doing the surgery, I’d do it again without hesitation.

      I never trusted the pupil measurement I got from my laser-eye doc. Well, I did trust it for some conditions, but not others. The room we were in was not super dark, so I knew my pupils were not at their widest. If your pupils were measured in a fairly light room, then your ‘widest’ pupil size may not be all that wide.

      Before surgery (as I got closer and closer to the date), I measured my pupils at home. Image is on the article here:

      I went in my completely darkened bathroom (no windows) and set my SLR camera’s attached flash to bounce off the ceiling. It was pitch-dark the instant before the blinding flash went off. And on that image, when I used the measurement tool in Photoshop to compare it to the ruler, the pupils were about 8mm diameter.

      I forget exactly what the laser system’s true corrected zone was when I got mine done, but I don’t think they’ve improved beyond that 6mm or so. It’s possible that the only reason I see halos in the very dark are because my pupils only go so wide when they’re very dark. (Making the laser-eye doc’s measurements fairly reasonable, as I’m happy with my haloing side-effects on the whole).

      Obviously I still went with the surgery, so I was willing to accept the outcomes. And I since have. Still no regrets about the surgery at all. Though I understand I’m one of the majority (but not 100%) who had no serious or unexpected side-effects.

      Hope that helps!

  25. Thank you so much for your extensive reply!!!
    I’m not really sure about the laser treatment zone as I didn’t found it on their website (which is a bit strange, maybe I just have to look a bit better). On some others sites I read both 6.0 and 6.5, so if 6.5 mm is possible I guess I would have no problems at all.
    My pupils were dilated with drops and were really huge when I got out of the hospital, they don’t look that big the second I switch on the light in the bathroom after some time in complete darkness… so not really sure if the 6.4 mm they measured at the visit is really how big they actually get in complete darkness.
    I live in the countryside as well and the streets I’m driving on at night are really dark, so good to know I might have some light problems. But if I understood correctly, you have no problems at all when you switch the overhead light on, so I’m glad to read that there’s a simple solution to it if it would bother me!
    Thanks again for your reply!

  26. Hi! I live in Vancouver, and am wondering if you would be able to email me to let me know which clinics you were considering and which one you selected! My husband selected Coal Harbour for his surgery, and I have also done a consultation there, but am wondering if I should widen my search with different clinics. Thank you!

  27. Hi Mr. Temple,

    I am also considering to undergo corrective eye surgery but I’ve been having a lot of concerns over the overall safety and which type I should choose. I went in for a consultation and the doctors never told me that the corneal flap never heals, until I read your post. That really worries me.

    During the consultation, the clinic told me about a new laser treatment called IntraLase SBK. They say that “this is a hybrid procedure which combines the safety of PRK as well as the quicker recovery of LASIK.” Two lasers are used – one is to create a flap (without the blade that LASIK uses) and the other to correct the vision after the flap is opened. The doctors told me that the infra red beam creates a much thinner, tailor-made flap that’s superior in structure to a conventional LASIK flap.

    I was wondering if you know any information about this third type of laser treatment – IntraLase SBK and if this would be the preferred choice over PRK and LASIK. Any information that you may have is very much appreciated. Thankyou!

    • Intralase SBKcuts a flap in your cornea, which never heals. It may be a more precisely deep flap, but it is still a cornea flap, with all the added risks that entails. The only ‘benefit’ comes in recovery time. You risk long term health for the sake of a few weeks of recovery.

      I would never have a corneal-flap operation.

  28. Mr. Temple,

    Thanks for a wonderful writeup – easily the most informative blog on refractive surgery I’ve been able to find.

    I’m due for Epi-Lasik in a week and I’d like to learn more about your experience with the steroid drops regimen. How specifically was the dose/frequency adjusted based on your day-to-day recovery? I believe I won’t see my surgeon post-op until the 5th or 6th day to get the bandage removed, and I wanted to see how I can do to enhance my chances.

    Many thanks for your help!

  29. Hi Mr. Temple,

    I couldn’t say thank you enough for your post. I was on the fence about this surgery for two years and only till after reading your post, I have a much better idea of what I will get through the surgery.

    Still, I have several questions please. You mentioned that there are lots of laser surgeries and I am wondering are there different types of PRK surgeries as well? If so, what are they?

    Also, could you give me an idea of how long after the surgery I can use computer all day for work?

    Thank you so much once again!!


  30. Mr Temple – thank you so much for this writeup! I’ve spent some time looking at your many entries on PRK. I went for a LASIK consultation this past Monday at a LASIKplus clinic. I was very upset to find out that I was probably not a candidate for LASIK because of a corneal irregularity caused by my contact lenses, which might make it unsafe to cut the flap. I went for a follow-up with the surgeon today so that he could take a look himself and confirm, and he did indeed say that the irregularity is too steep for LASIK to be an option, but that I am a very good candidate for PRK! I had no idea what that was, and asked tons of questions, and then came home and googled even more questions, which is how I ended up here.

    I don’t really have anything to add to the conversation, I just wanted to say that I’m very very happy I found your page. I am now feeling very relieved that LASIK is not an option for me, because if it was, I probably would have gone through with it! Strangely enough, I’ve been putting it off all these years because I was scared of that flap (which I’ve always known doesn’t heal). And, if this isn’t serendipity, I don’t know what is – had I done a LASIK consult several years ago when I first considered it, the damage to my cornea probably wouldn’t have been done yet, I would have been a good candidate, and I would have gone through with it, AND I’m sure I would have had a complication by now as I’m a very active person. (I kayak, I have small children, and I have a very bad eye-rubbing habit.)

    Anyway, my vision prescriptions have been mostly stable (I think it changed slightly last year but not the two years before, or something like that), so I’m hoping to go through with the PRK here in the next couple of months! I’m so nervous but you’ve made me feel loads better, so thanks for that. :) Cheers!

  31. Greetings…great articles. Best I’ve seen by far. Especially post op re drops and tin foil on windows!
    Question. I have some glare and halos from post cataract surgery, July 2017. My Tecnis Z9002 lens size was 6mm. It is of course behind the cornea….but is that sizing relative to my pupil size causing halos? Worse is night single point lights, IE headlights I have halo about 6-10 feet radius. Also Pinkish orange street lights have huge 20-30 ft halos. Glare from florescent lights is annoying too. Stars, far away have none.

    I have planned for some touch up PRK due to over correction in cataract lens RX.
    Best from Colorado

  32. my doctor uses Schwind laser 750
    and when she tested my pupil size it was 7.5 in darkness without drops in my eyes.
    she measured using Schwind Sirius

    which i put my face inside this machine and i saw full dark inside with one red circle in front of my eyes and the room lights was turned off also.

    when i asked about halos , she said that i may see halos just if in total dark room as the dark in i saw in the machine.

    i know that Schwind optical zone is 6 mm. so Im worried that my full dilated pupil is 7.5 .
    cuz what if my pupil is dilated in other situations ? when we get happy or angry or excited our pupil also gets wider.
    or do you think in these other situations the pupil doesn’t be full wide.
    or I should better do my laser surgery with a clinic that uses Star S4 IR laser which i think it can have optical size up to 8 , is that right ?

    • Hi Sally, thanks for your comment!

      I’d be careful with ‘treatment zones’ and ‘optical zones’ and any other terminology when reading laser doctors’s websites. Most (all?) lasers have a primary zone where the full-prescription treatment is applied, and then a tapering zone in which there is lasering, but which does not have the full prescription applied. Only the primary area (‘optical zone’ I often hear it called) matters. And if it’s smaller than your pupil size, you will be subject to halos in certain situations.

      I am not super familiar with the suite of lasers, but I did find the following after googling ‘Star S4 IR laser treatment zone’…

      First, from the FDA’s website, is a document from the Star S4′s approval process (which was in 2003, so fairly old):

      It lists a 6.0mm ablation zone (presumably with a larger taper area). Pretty standard in lasers of that era.

      I understand that some of the newer lasers can have larger optical zones, but I’m not familiar with them.

      Second, I found this thread on reddit discussing the S4 laser. One user comments with a few suggestions of lasers with larger optical zones:

      /u/LilaLaLina: “Definitely don’t do it with that laser. Go for a treatment that uses a full 7.5mm optical zone and blends to 9.5mm. LASIK, PRK or SMILE with more modern lasers from Zeiss, Wavelight or Schwind should be able to give you a proper treatment.”

      As for halos themselves, I wrote an article which should answer a few of your questions:

      Specifically with your question about fear/anger dilation, I don’t think you’ll have to worry about that much (at all?).

      Halos related to pupil size are caused because the pupil expands larger than the optical zone, so some of the light entering the pupil is not corrected for your prescription. This light is shone blurry on the retina instead of in focus (like your uncorrected eye). So, you get halos of uncorrected light overlapping the in-focus light hitting your eye.

      In practice however, there is quite a bit less uncorrected light entering the eye than through the corrected area of the pupil.

      For example, a 7.5mm pupil only has 25% of its surface area outside the 6mm diameter inner area, while a very large 8mm pupil has 44% of its area outside the 6mm.

      I suspect bright-light dilation of your pupil would rarely (if ever) get to quite that large, but even then, the light is far overpowered by the light entering the corrected area of the pupil.

      And because the uncorrected light is diffused much more than the corrected light (it’s blurry and spread out), the brightness of the halo is reduced quite a bit from those 25% and 44% numbers. So, the halo-light is much dimmer than the source light, and if the ‘spillover’ halo-light overlaps other light image, it’s going to be very hard to notice.

      Really the only time I’ve ever seen haloes is when driving at night on a dark road with no street lights. I’ll get halos on oncoming headlights, reflectors, and on street/road signs with high-reflective paint (never from a non-reflective surface). It’s never so bad that I cannot read a small roadsign in the dark, but I do see the halos around them.

      Those are the only conditions where my pupil is larger than my optical zone (even a few orange streetlights are enough to dilate my pupil enough), and when the ‘spillover’ uncorrected light is brighter than the pure darkness outside the bright point-source of light.

      I knew going into my surgery that my pupil could dilate larger than my optical zone, but I decided for the above reasons that I’d be okay with it. To be honest I didn’t notice the nighttime halos until I moved to the country. Nowhere in the city at night was it dark enough for my pupils to fully dilate while out and about. The one place I did notice halos was in my bathroom with no windows. It could get pitch-black, and I had a small green LED on a charger that would halo. If I turned my phone screen on and pointed it at my face (not even directly or all that close), that would provide enough ambient light to dilate my pupils and make the halos disappear. I had fun with it. :) “Honey, what are you doing in there?” “Playing with my pupils!”

      Now that I live in the country, I see halos quite a bit when driving on very dark roads when there’s a reflector or reflective street sign. I can make them disappear by turning on one of the map-lights in my car. When I do that, I can still see outside the car very well, so the light isn’t super bright, and it’s fun to watch the halos shrink into the point-light sources as my pupil contracts. My halos are never more than an amusement to me, and I don’t feel any need to mitigate them. And I don’t really notice them, except when I’m playing around with them again. :)

      Does that make a certain amount of sense?

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