Eyeworld

EW RESIDENTS 48 November 2016 respect to uncorrected (p=0.1) and corrected (p=0.4) preoperative visual acuities, refraction stability, and contact lens holidays. At the day 7 postoperative examination, there was a signif- icant difference in uncorrected (0.14±0.16 and 0.03±0.13 logMAR for transPRK and femtoLASIK, re- spectively, p=0.0001) and corrected (0.09±0.12 and –0.06±0.06 logMAR for transPRK and femtoLASIK, re- spectively, p=0.0001) distance visual acuities between groups. There was also a significant difference in mean spherical equivalent (0.04±0.47 D and –0.12±0.52 D for transPRK and femtoLASIK, respectively, p=0.002) and mean astigmatic (0.19±0.41 D and 0.29±0.34 D for transPRK and femtoLASIK, respectively, p=0.006) refractive error between groups. At the 3-month postoperative examination, there was no signifi- cant difference between the groups in mean uncorrected (–0.01±0.15 and –0.01±0.12 logMAR for transPRK and femtoLASIK, respectively, p=0.4) or mean corrected (–0.08±0.08 and –0.08±0.06 logMAR for transPRK and femtoLASIK, respectively, p=0.4) visual acuities. However, a signifi- cant difference in mean spherical equivalent (+0.11±0.51 D and –0.08 ±0.40 D for transPRK and femto- LASIK, respectively, p=0.0001) and mean astigmatic (0.34±0.45 D and 0.27±0.30 D for transPRK and femto- LASIK, respectively, p=0.03) refrac- tive error was present. Lastly, at the 12-month post- operative examination, there was a significant difference in mean uncorrected (–0.05±0.14 and –0.01±0.14 logMAR for transPRK and femtoLASIK, respectively, p=0.005) and mean corrected (–0.11±0.06 and –0.09±0.05 logMAR for transPRK and femtoLASIK, respectively, p=0.03) visual acuities as well as mean spherical equivalent (0.11±0.56 D and –0.09±0.46 D for transPRK and femtoLASIK, respectively, p=0.0001) refractive error between the two groups. There was no significant difference in astigmatic error. The achieved versus attempted refractive correction outcomes were also assessed. There was no signifi- cant difference in spherical equiva- lent correction between the groups. There was, however, 8% overcorrec- tion of astigmatism in the transPRK group and 1% undercorrection of astigmatism in the femtoLASIK group. Overall, 83% of the transPRK eyes and 85% of the femtoLASIK eyes were within 0.5 D of their target refractive goals. Both treat- ment groups demonstrated overall stability in their postoperative visual and refractive outcome during the follow-up period. The uncorrected visual acuity stabilized earlier for the femtoLASIK group (3 months) than the transPRK group (up to 12 months). Similarly, the postopera- tive astigmatic error in the femto LASIK group stabilized between the 7-day and 12-month follow-up, whereas the transPRK group stabi- lized by 3 months. In the discussion, the authors comment on the higher variance noted in transPRK patients, which they attributed to the use of popula- tion-based epithelial profiles rather than individualized, patient-spe- cific profiles. Despite this variance, however, there was not a clinically significant difference in final visual acuity outcome for transPRK pa- tients at 12 months compared to the femtoLASIK group. They concluded that transPRK seemed to feature comparable if not better long-term visual outcomes than femtoLASIK, but that femtoLASIK featured faster recovery times. Despite these differ- ences, however, they concluded that neither procedure can be considered superior based on this single retro- spective study. Comments While a prospective, case-matched controlled study or a randomized clinical trial would be more desired, the authors attempted to limit bias of their retrospective comparative series design by using a consecu- tive series of transPRK patients and matching them with the femto- LASIK population during the same time period. While the average age of transPRK group was statistically significantly lower than that of the femtoLASIK group, this is unlikely to have any clinical significance. Decision for transPRK was based on patient and surgeon preference as well as corneal thickness, which adds an element of selection bias, especially when 11 surgeons were included in the study. However, the use of two identical laser units does help in normalizing the sample. The exclusion criteria used by the authors helps to generalize the study results to healthy refractive surgery candidates. Interestingly, corneal topo- graphic and thickness analysis was performed solely with the Nidek Review continued from page 46 From left: Kyle Rogers, MD, Russell Burks, MD, James O'Brien, MD, Clifton Fay, MD, Andrew Rodenburg, MD, Jason Smart, MD, Christina Lippe, MD, Joshua Hendrix, MD, Valerie Lobodiak, MD, Andrew Melson, MD, Ilya Sluch, MD, Vincent Venincasa, MD, and R. Michael Siatkowski, MD Source: Dean McGee Eye Institute

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