PRK or Lasik for 8+ Myopia?

I'm looking at getting lasik or PRK performed. My script reads (sph, cyl, ax) (-8.75, +2, 085) and (-8.00, +3.00, 080). My first consultation was last Saturday. With my correction, cornea shape, and pupil size, they recommended PRK. In response, I emailed PRK questions to my other clinics. One of them responded immediately that with over 5, they would not recommend PRK due to haze. They said that the first clinic had older lasers, which would not be sufficient lasik for me. Please help!

Doctor Answers 4

PRK vs Lasik to Correct Myopia

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It is important to know that both of these procedures are excellent at correcting this level of nearsightedness. As with anything in life, there are things to consider with each that might make one choose one over the other. PRK involves the removal of the epithelial layer of the cornea, then the laser pattern is applied and a bandage contact lens is placed in the eye for about 4 days while the surface recovers. Lasik, on the other hand, involves lifting up this outer layer(I create a corneal flap with a femtosecond laser), then applying the identical laser pattern to the cornea. The next step involves putting the surface flap back in position.

It is clear by the above description that PRK would have a slower visual recovery than Lasik, so I tend to do more Lasik than PRK, and this is true of most surgeons. There are times, however, when the patients cornea is on the thinner side, that we might recommend PRK over Lasik, from a safety perspective.

The bottom line is that both procedures are safe and effective and, with over 15 million of them now having been done worldwide, time tested. The best way to proceed is to find a surgeon that you trust and go with their advice. If you need two or three opinions in order to become comfortable, that is OK. I have some videos describing both PRK and Lasik on my website.

Baltimore Ophthalmologist

Lasek lasik epilasek for high hyperopia

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since your myopia is very high, i would suggest you avoid getting LASIK, because your residual stromal thickness, which is the amount of untouched cornea, would be very close to 250 microns, which is the absolute lower limit of safety after LASIK, or else you risk developing KC, for which you might need a corneal transplant, and is the #1 reason surgeons are losing lawsuits after LASIK

this is why i switched from performing LASIK to LASEK/epiLASEK, as by not cutting a flap, you save about 150 microns of tissue. even IntraLase, which is cutting a flap with a laser, cannot cut a flap reliably thinner than 100 microns, so you'd save 100 microns by not cutting an intralase flap.

you have to remove or photoablate (vaporize) a certain amount of corneal tissue to treat every diopter of prescription. for your rx of -9, you would need about 100 microns of tissue removed for a standard ablation, and almost 150 microns for a custom wavefront ablation, which is what every patient should get, provided they have sufficient corneal tissue

just doing the math makes this clear: starting with an average corneal thickness of 500, if you cut a flap that uses up 150 microns, and then you need to ablate another 150 to get rid of your rx, you wind up with a residual of 200, or LESS THAN IS SAFE so you might need a PK (transplant)

even if you get Intralase, you start w 500, remove a 100 flap, laser off 250, and now you're down to 250, which is the bare minimum of safe-- and you cannot get an enhancement even if you needed to. 

with  Advanced Surface Ablations ie LASEK and epiLASEK, the math looks like this:

500 minus ZERO (NO FLAP) - 150 (laser ablation) = 350 or way more than the 250 limit, so your cornea is much thicker, stronger, and safer, with no risk of KC or needing a PK

you should also NOT get a PRK or your may SCAR as that is the old  way of doing a surface ablation, and prone to scarring in high prescriptions (like yours)

anyway, that's a very detailed and complete explanation, i hope it's appreciated and not too complicated:)

Emil William Chynn, MD, FACS, MBA
New York Ophthalmologist


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First off your spherical equivalent would be -7.75 right eye and -6.50 left eye.  LASIK candidacy would ultimately be dependant on your corneal thickness and curveature.  Is there enoug tissue to treat?  Is your cornea steep enough to treat?  

Surface treatments such as PRK or LASEK would preserve more corneal treatment.  There is a slower healing process, but if done with mitomycin c (MMC) would have minimal haze risk.

LASIK would provide a faster recovery but carries the flap complications.

The accompanying video will explain the anatomical differences between the procedures.

A final option would be the ICL, an implantable lens to improve vision.

I think the most important thing you can do is to seek the advice of a refractive surgeon who is well versed in all refractive techniques.  It doesn't sound like this has been the case thus far.

Good luck!

Cary M. Silverman, MD
West Orange Ophthalmologist

Lasik vs prk for -8 myopia

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Without knowing your corneal thickness or the appearance of your corneal topography, it is difficult to comment on your situation specifically. In general, for a surgeon who does both lasik and prk, lasik would be preferable for higher levels of myopia because healing is more predictable. However, relatively thin corneas and some topography patterns would tilt things in the direction of surface ablation (PRK, lasek). If you have any uncertainty about how to proceed, it's probably a good idea to get another consultation. 

Howard S. Kornstein, MD
White Plains Ophthalmologist

These answers are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.