Myopia: wavefront-guided PRK or wavefront-guided LASIK?

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Myopia: wavefront-guided PRK or wavefront-guided LASIK?

San Diego--Results from 12 months of follow-up in a prospective, randomized study show wavefrontguided PRK (WFG-PRK) and wavefront-guided LASIK (WFG-LASIK) are similarly safe and effective procedures for the treatment of low-to-moderate myopia. WFG-LASIK, however, offers a  definite advantage of faster visual recovery, said  definite Capt. David J. Tanzer, MD. The investigative device exemption study was conducted at Naval Medical Center San Diego to evaluate the efficacy and safety of WFG-PRK, which is not an FDA-approved procedure, and to  validate further the safety of WFG-LASIK in a larger warfighter patient population. The study enrolled 200 subjects with myopia between -1 and -6 D and up to 2.5 D of astigmatism. The participants were randomly assigned to undergo bilateral WFG-PRK or WFG-LASIK, and the two treatment groups were well-matched at baseline with respect to mean age (~30 years), mean sphere (~-2.7 D), mean cylinder (-0.7 D), and mean SE (-3 D). Outcomes comparable

By 6 months, outcomes of the two procedures were essentially comparable for predictability, safety (change from preoperative best spectacle-corrected visual acuity [BSCVA]), quality of vision metrics (higher-order aberrations [HOAs] and low-contrast acuity), and the participants' subjective appraisal of outcomes. However, there was an early loss in mean best-corrected visual acuity (BCVA) in the WFG-PRK group and there were highly statistically lasik eye surgery recovery significant recovery significant differences favoring the WFG-LASIK group for better uncorrected visual acuity (UCVA) through 3 months as well as for better predictability. "Based on the results of this study, WFG-PRK is clearly a safe and effective procedure, and the slower visual recovery in the WFG-PRK group was expected," Dr. Tanzer said. "However, in our population, it represents the Achilles' heel that hampers us from performing surface ablation procedures, especially for personnel with warfighter status. "WFG-LASIK with femtosecond laser flap creation is the refractive surgery procedure of choice for warfighters who are then eligible sooner for return to full duty and deployability," he added.


 All of the ablations were performed using a certain platform (Star S4 CustomVue platform with the 3.64V Fourier software, Abbott Medical Optics) using no nomogram adjustments and with a 6-mm optical zone and 8-mm transition zone. Dr. Tanzer and Steven Schallhorn, MD, principal investigator for the study, performed all of the procedures. Epithelial removal was done using an Amoils brush for the PRK procedures, and the postoperative regimen included bandage contact lens application, nonpreserved tetracaine drops, topical antibiotic, and 2-month corticosteroid taper. LASIK procedures were done with a 15-kHz femtosecond laser (IntraLase) to create a 100- or 110?m thick flap with a 9.2-mm diameter. Patients received a 1-week postoperative course of topical antibiotic and corticosteroid.  At 1 week after surgery, there was a clear and highly statistically significant difference in the UCVA  outcomes favoring the LASIK procedure. UCVA of 20/20 or better was achieved by 94% of eyes treated by WFG-LASIK and 42% of those that had WFG-PRK; UCVA was 20/16 or better in 78% of  WFG-LASIK eyes but in only 10% of eyes treated with WFG-PRK.  A statistically significant difference favoring WFG-LASIK for better UCVA outcomes was maintained at 1 and 3 months. At 3 months, 96% of WFG-LASIK eyes and 92% of WFG-PRK eyes achieved UCVA  of 20/20 or better, and rates of 20/16 or better for the two groups were 87% and 80%, respectively.

By 6 months, there was still a numerical difference in UCVA outcomes favoring the WFG-LASIK  group, but the differences were not statistically significant. BSCVA analyses showed a significant difference in the safety margin favoring LASIK at 1 month when there was a mean, statistically significant gain in logMAR BSCVA in the WFG-LASIK group and a mean loss in the WFG-PRK group, +0.04 versus -0.003. At 6 months, both the WFG-LASIK and WFG-PRK groups had a statistically significant mean gain from baseline logMAR BSCVA, +0.05  versus +0.04, but there was still a statistically significant significant difference favoring LASIK. By 12 months, both groups achieved a further mean gain but the difference between groups was not statistically significant. Quality-of-vision assessments included measurement of low-contrast (25% mesopic) BCVA, and there was no statistically significant difference between groups at any follow-up visit. Both treatments caused a slight induction of HOAs. While there was no difference between groups at 1 month, induced HOA at 3 months was slightly and significantly greater in the WFG-LASIK versus WFG-PRK  group, 0.1 versus 0.05 ?m. -medicine-feature-articles/myopia-wavefront-guided-prk-?page=full

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