Photorefractive keratectomy using the summit SVS Apex laser with or without astigmatic keratotomy.
OBJECTIVE
The purpose of this study was to evaluate the results of myopic photorefractive keratectomy (PRK) with or without astigmatic keratotomy (AK) for different levels of intended correction by using the SVS Apex laser.


METHODS
This is a retrospective cohort study of 226 eyes that had PRK for myopia ranging from -1.0 to -7.6 diopters and 6 months of follow-up. In addition, 64 of these eyes had AK for naturally occurring or laser-induced astigmatism. Uncorrected visual acuity, spectacle-corrected visual acuity, and corneal topography with quantitative descriptors of surface regularity (SRI) and surface asymmetry (SAI) were used to monitor the results of PRK with or without AK.


RESULTS
At 6 months, 95.6% eyes had an uncorrected visual acuity of 20/40 or better, 90% eyes were within +/-1.0 diopter of emmetropia, and 3.1% eyes lost two lines of best-corrected vision. No eyes lost more than two lines of best-corrected vision. Mean refractive astigmatism was reduced, but mean SAI and SRI were increased, 6 months after PRK. Uncorrected vision, best-corrected vision, and predictability decreased, whereas SAI and SRI increased, with increasing attempted correction.


CONCLUSIONS
PRK, with or without AK, effectively reduced myopia in all eyes by 6 months after surgery. Predictability tended to decrease with increasing attempted correction, even for eyes with relatively low to moderate myopia. PRK may induce surface asymmetry and irregularity at 6 months, and these alterations tend to be greater as the attempted correction increases.
Eye Institute and Department of Cell Biology, The Cleveland Clinic Foundation, Ohio, USA.
S S
SS
Shah
M S
MS
Kapadia
D M
DM
Meisler
S E
SE
Wilson
D001251:Astigmatism / Q000601:surgery*; D015331:Cohort Studies; D003315:Cornea / Q000601:surgery*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D054018:Lasers, Excimer; D008297:Male; D009216:Myopia / Q000601:surgery*; D018903:Photorefractive Keratectomy; D012189:Retrospective Studies; D014792:Visual Acuity