This study group compared contrast sensitivity among participants undergoing wavefront-guided or wavefront-optimised photorefractive keratectomy (PRK) or laser-assisted in situ keratomileusis (LASIK) for the treatment of myopia or myopic astigmatism 12 months after surgery. This was a prospective, randomised clinical trial, 215 participants with myopia ranging from -0.50 to -7.25 diopters (D) and less than -3.50 D of manifest astigmatism electing to undergo either LASIK or PRK and randomised to receive wavefront-guided or wavefront-optimised treatment. Corrected Super Vision Test (Precision Vision, La Salle, IL) high contrast and small letter contrast sensitivity, uncorrected postoperative contrast sensitivity function, and uncorrected and corrected distance visual acuity were measured preoperatively and at one, three, six and 12 months postoperatively. There was a significant difference within each of the four groups over time when measuring high contrast visual acuity (p<.001) and small letter contrast sensitivity (p<.001), with the most significant decrease occurring one month postoperatively. However, there were no significant differences when comparing the four groups for high contrast sensitivity (p=.22) or small letter contrast sensitivity (p=.06). The area under the logarithm of contrast sensitivity function did not differ significantly over time (p=.09) or between groups (p=.16). A pairwise comparison of preoperative to 12-month corrected distant visual acuity (CDVA) showed a significant improvement in all groups (p<.017). The change in CDVA was also significantly different between groups as determined by one-way analysis of variance (p=.003). In this prospective study, the authors found there was no significant decrease in corrected high contrast visual acuity or corrected small letter contrast sensitivity in any treatment group at the 12 months follow-up period. Wavefront-guided and wavefront-optimised PRK and LASIK procedures maintained high contrast, small letter contrast sensitivity, and contrast sensitivity function 12 months postoperatively. Although the recovery period for visual performance was longer for PRK versus LASIK, there was no significant difference in treatment type or treatment profile at 12 months postoperatively.

Contrast sensitivity after wavefront-guided and wavefront-optimized PRK and LASIK for myopia and myopic astigmatism.
Ryan DS, Sia RK, Rabin J, et al.
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Inderpaul S Sian

FRCOphth, MCOptom, PG Cert (Clin Ed), MB ChB, BOptom (HONS), Musgrove Park Hospital, Taunton & Somerset Foundation Trust.

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