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Comparison of different types of cylindrical orientation in myopic LASIK
200 myopic wavefront optimised LASIK cases were retrospectively evaluated for: UDVA, CDVA, Refractive error (RE), topography, tomography. Use of pre-op data available were used to also generate virtual topography-guided LASIK (tgL) plan with topography-modified refraction (TMR) for the cylinder amount and axis adjustment, and correlated to the actual residual refractive and topographic data available. Comparison between the 3 groups was made.
In consecutive myopic LASIK the relative distribution of naïve astigmatism was: WR:171 (85.5%), AR: 10 (0.5%), OC: 19 (0.95%). Overall post-LASIK data for all 3 groups: UDVA: 20/22, CDVA 20/20, RE in Diopters: -0.35 sphere and -0.75 Cylinder. Breakdown for each group was: Residual refractive error of over -0.25 Diopters: WR: 76%, OC: 15%, AR: 9%. When speculating the use of TMR at that time: It would have reduced the residual refractive cylinder in WR more than the AR and then more than the OC group, that appeared to perform best in this regard with WFO LASIK and the clinical refraction used at the time.
Standard Clinical refraction used in WFO LASIK may result in residual refractive cylinder more in with-the-rule candidates. Using TMR and topography-guided LASIK instead may offer improved outcomes through accurate cylinder correction.