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Re: Myopic (Over)Correction in Younger Patients

Hi Kamran

Pls see below

Emil William Chynn, MD, FACS, MBA


1st eye surgeon in NY to get LASIK himself (1999)

Performed 5,000 LASIKs from 1996-2002

Switched to non-invasive LASEK in 2003

Have performed more LASEKs than any MD in US

102 E. 25th St. (& Park Avenue South)

(212) 741-8628    (212) 741-2390-fax

Sent from my EyePhone so pls excuse abbrev?

On Jun 13, 2015, at 11:17 AM, Kamran  wrote:

Hi Emil

I hope you are doing well. I wanted to ask you a question in regards to a comment that you had made about slightly overcorrecting younger myopic patients who undergo refractive surgery (regardless of ASA/PRK, LASIK, etc). You had mentioned that it’s preferable to make them slightly hyperopic, thus as they get older and develop some regression as they get older, they’ll end up back closer to plano. I think it’s a good idea, and have heard very few people talk about it. No one in fellowship (I finished my fellowship in 2013) mentioned this, and logically, it has a lot of merit

I’ve been running my own SF Match fellowship for over a decade, and also have had many “open access” surgeons use my facility. One of the first things they need to get used to is the concept of overshooting young myopes. You can’t get your long-term (ie if your patient EVER needs and enhancement, not only within 1 yr) down as much as possible unless you overshoot

A couple of questions: 

1. Do you have a nomogram that you use for this? For example, do you do more over-treatment for a patient who is 22 years old vs someone who is 28 years old? What range of targeted hyperopia do you use accounting for the age of the patient?

Yes. It’s based on several factors:

Age (and years until age 30)

Past myopic progression

Amount of near work:


If they plan on going to graduate school

How “smart/studious” they are

If they “like to read”

How much they’re on a computer/tablet

Myopic progression is typically asymptotic and flattens out at age 30. So you have to graph out a curve

It’s vital to get old Rxs. Yesterday I delayed surgery because my fellow accepted a 1 year history of eyeglass Rxs. That’s not a history. We make all our patients give us all of their old Rxs. A Rx from 3-5 years ago is more useful than one from 1-2 yrs ago

For example 2 -3.75 myopes age 23 come for LASIK. Both have glasses 1 year old that read -3.50. What would you shoot?

Most surgeons would shoot -3.75 and call it a day. Maybe -4.00. I tell my fellows that’s like “pissing in the wind” (an American idiom about something you shouldn’t do because the force of nature will overwhelm your puny efforts to go in some direction)

Let’s say that patient is a landscaper, says he doesn’t like to read and is rarely on computers, and you obtain an old Rx that’s 5 years old and -3.25. You can see he’s progressing very slowly, only .25D/5yr, and as you graph out a myopic progression line that’s asymptotic at age 30, so overshooting his current -3.50 by -.25 is appropriate

What about a girl with the same age and current Rx, who had an old Rx that’s 5 years old, but -2.75, and is Asian, both parents are myopes, her older siblings are all high myopes, who’s a graphic designer and planning on going to graduate school in the fall? Graph it out, asymptotic at age 30. You’d have to shoot at least a -4.25 to have any hope of accounting for all or at least most of her myopic progression. Otherwise you’re guaranteeing she needs an enhancement or is back in glasses by age 30

2. I know you mainly do ASA… does your targeted hyperopia only work for ASA or would it apply to LASIK as well? (I would think it would, but figured I would ask) 

I was doing this from 1997-2003 when I did 5,000 LASIKs. Having a better Nomogram that factors in myopic progression on young myopes is better for all types of procedures. The eye is obviously still going to progress at the same rate as if you didn’t laser the patient 

I started to investigate this when I was a cornea and refractive fellow under George Waring, Doyle Stulting, Keith Thompson, and David Palay in 1996-7. This was back when every other cornea fellowship was 99% cornea and 1% laser, but I was mostly interested in laser,which is why I chose them

They had an “age factor” in their Nomograms (as was common back then) that they were just in the process of removing, so one of my attendings (probably George) assigned me to look at how age affects results. I found that age doesn’t affect achieved ablation depth or REGRESSION, but does affect PROGRESSION. Only after my chart review of 100 charts with years of follow-up did it become clear that PROGRESSION was often a much larger contributor to the need for an eventual enhancement years down the line than REGRESSION. So it must be included in surgical planning to get enhancement rates down as low as possible 

3. Does your choice of excimer laser affect how much you would aim for hyperopia? Meaning that since the older lasers had more chance of causing regression, would you aim for more hyperopia if you were using an older laser? I currently have access to both a VISX S4 and an Allegretto laser. I much rather prefer the Allegretto, but depending on patient geographical preference of laser center, I use what’s available. 

It’s not REGRESSION it’s PROGRESSION! Accurate Nomograms must account for both!

Regression happens in the first few weeks after myopic LASIK, months after myopic surface ablations and Hyperopic LASIKs, and many months after hyperopic surface ablations. It’s due to asymmetrical epithelial hyperplasia, where the eye tries to revert to its original curvature by filling in part of the ablated depression with epithelium

In surface ablations you should retard regression by doing a long steroid taper on the higher Rxs (which also prevents scarring)

In overcorrected surface ablation pts, you can promote regression and epithelial hyperplasia by switching from a steroid to a NSAID so you can avoid an enhancement. The switch must be made by 1 month Postop and you need to dose the NSAID QID  for 1-3 months. You don’t need to use a BCL. In hundreds of applications I’ve seen zero melts. I’ve said before on this forum I think that concern is based on flawed data involving an isolated genetic NSAID that was removed from the market

4. At what age range would you NOT aim for targeted hyperopia?

It’s not just an age thing. Once your data of old and new Rxs show no more progression, and/or the patient is 30 or over, they’re not progressing anymore, so you don’t need to overshoot to account for profession 

I find it amazing that most doctors performing laser vision correction are only taught to think about the more minor regression, and not the more major progression when creating shoots. Of course, you can just tell patients to wait until they’re 30, but then they’ll just get lasered by someone else who also probably doesn’t factor in myopic progression

So initially you make the young 20 yo myope something like +.75, so he’s 20/15 and as symptomatic ecstatic BC of accommodation, let’s say in 5 years he’s plano, and then in 10 years he’s -.50 and still 20/25 and happy and doesn’t need an enhancement and has low myopia to help read when he’s 50??

Without overshooting this same patient would be -1.25 at age 30, pissed, and tell 100 people “LASIK isn’t permanent”??

No wonder LASIK hasn’t taken off like it should!?




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