Q:
New pt came to see me earlier this week for a refractive evaluation. 26yo male with past ocular hx of high astigmatism, no family hx of keratoconus. Highly motivated, and understands higher likelihood for enhancement. I was thinking of ASA for him, but wanted some input.
BCVA OD: +0.5-4.50×005 20/25 pach 588
BCVA OS: +2.25-6.00×180 20/25 pach 544
I am currently using the VISX S4 platform. I have not ever attempted to treat this level of cylinder. Thoughts?
A:
i’m on the same laser (VISX S4 IR) so my experience should be very relevant to your outcomes
on this platform, i can reliably eliminate about up to 4D of cyl with LASEK
back when i was doing LASIK on the same laser, i could only reliably eliminate 3D or so of cyl
i’m not sure of the reason, but my conjecture is that perhaps the flap is obscuring/diminishing some of the laser effect
i’m curious if anyone else has observed they can reliably treat higher cyl with ASA vs LASIK
i don’t know what the group’s consensus is, or the literature statistics show
but i have actually never seen a patient who has significant hyperopia eventually manifest as a true KC patient
the left eye is another matter. obviously, there’s no way to reliably get rid of 6D of cyl with any laser procedure
so i would just tell him that i’d be able to reliably get rid of at least 4D, perhaps leaving him with 1D of cyl
however, he might also be left with some residual hyperopia
so if his residual Rx is +.50 – 2.00 x 180, his SE = -.50, which is compatible with a UCVA of 20/25
even if he had a residual Rx that was worse and an UCVA of 20/40, i bet he might elect not to enhance anyway
as he would presumably be 20/20 OD, so 20/20 w both eyes open anyway
so i’d just tell him all of this (depending on how much he would understand, of course)
which is really probably a better “informed consent” than just saying something generic like “you might need enhancement”
i disagree with jim that if there is a higher chance of enhancement, then LASIK would be preferred
many recent studies in the literature have quantified the risk of epithelial ingrowth
it has been estimated to be about 1% in primary cases (this includes visually insignificant ingrowth, of course)
and about 10% in secondary cases
so if you think you might need to enhance someone (eg there’s no way you can get rid of >4D of cyl all at once)
if you then elect to perform a LASIK, you are basically saying you’re ok with a 11% risk of epi ingrowth
in my opinion, that’s a very high number to be ok with, especially as a “better default”
i really think the issue is that most surgeons are performing LASIK the vast majority of cases (like 90%)
so if you’re only doing 10% surface, you’re not so motivated to do an epiLASEK or whatever, so you do a PRK
then the recovery is very long, and then perhaps the bias shifts away from ASA to incisional surgery
i did an epiLASEK on my secretary who was -4.50, and she was 20/15 and with 0 discomfort 72 hours afterwards
i guess if she had LASIK she could have been so by 48 hours, but that 24 hour savings is clinically unimportant
hope this helps, and pls feel free to call back if you need any more specific advice;)
