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E.C. Lai, A. Kanellopoulos, L. Pe, M. Jankov, A. Papakostas, L. Sperber; Is Wavefront Necessary for Re–Treatments? A Comparison of 65 Wavefront–Guided LASIK Enhancements to 64 Asphericity–Adjusted Enhancements . Invest. Ophthalmol. Vis. Sci. 2006;47(13):524.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the safety and efficacy of asphericity–adjusted LASIK enhancements in comparison to our previously reported wavefront–guided experience, utilizing the Allegretto–Wave 400 Hz system.
64 consecutive LASIK enhancement cases underwent re–treatment of residual refractive error and asphericity adjustment to the Q value of –0.50, based on 20 degrees topographic measurement. All procedures were re–lifts of flaps and were performed with the Allegretto eyeQ 400 Hz excimer laser platform. We evaluated pre– and post–operative refraction, asphericity (Q value), total high order aberrations (RMSH), and the subset of Zernicke coefficients C7, C8 (both representing coma) and C12 (representing spherical aberrations), contrast sensitivity, and possible complications. Follow–up was 3–17 months (8.5). These data were compared with the same values recovered retrospectively from our previously reported experience with wavefront–guided LASIK enhancements.
122 eyes were included. In the asphericity adjusted group, the mean values were: refractive error: sphere: –0.80D (–0.50 to –1.75) and cylinder: –0.55D (0 to –0.75). UCVA improved from 20/25 to 20/18. At 3 months, 92% of the eyes were 20/20, 57% 20/15, and 34% 20/10. 100% of eyes were within +/– 0.5D of the refractive goal at 3 months. Q value changed from a mean of +1.29 to –0.11. There was a positive shift of Q value proportionate to the amount of refractive error corrected. The mean RMSH decreased from 0.25 to 0.10; C7 from 0.34 to 0.32, C8 from 0.55 to 0.54 and C12 from +1.11 to +0.03. Contrast sensitivity showed a 35% improvement. When compared to the previous wavefront–guided cases, there was no statistical difference in any of the parameters studied.
Asphericity adjusted LASIK enhancements with the ALLEGRETTO–WAVE system (a 0.9mm flying–spot and 400Hz) appears to be safe and very effective for correction of residual refractive error and cornea asphericity. When compared with the more laborious wavefront–guided experience, the improved parameters appear to be identical: UCVA, RMSH, and C12. This suggests that wavefront–guided treatments may be effective mainly through better approximation of emmetropia and better post–operative asphericity profiles and not an improvement of all Zernicke coefficients.
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