Wavefront-Optimized Versus Topography-Guided LASIK: Comparative Contralateral Eye Study
To compare the visual outcomes and higher order aberrations [HOA] following wavefront-optimized and topography guided treatments in fellow eyes of patients undergoing femto-second laser assisted laser in situ keratomileusis (LASIK) for myopia in virgin eyes.
This prospective comparative study included 20 patients who underwent wavefront-optimized (WO) LASIK in one eye and topography-guided (TOSCA- Atlas Carl Zeiss) LASIK in the fellow eye. The IntraLase FS 150Hz femtosecond laser was used to create a superior-hinged flap and the MEL80 excimer laser (Carl Zeiss Meditec AG), for photoablation. The WASCA analyzer (Carl Zeiss) was used to record preoperative and three months postoperative wavefront errors of the whole eye over 6mm pupil diameter which were decomposed into Zernike polynomials up to the fourth order and analyzed. The visual outcomes and changes in HOA were compared between the two treatment modalities.
Twenty subject [age 23.7± 2.9 years], had preoperative mean spherical equivalent myopic refraction of -4.2±1.2D and -4.4±1.3D in WO and TOSCA group respectively. At three months, 95% of eyes in the WO group and 100% in the TOSCA group had uncorrected visual acuity of 20/20 or better. Safety, refractive stability and predictability were similar in both groups. There was statistically significant increase in total higher order aberrations (RMS) from 0.24±0.06 μm, 0.22±0.06 μm to 0.39±0.14μm [P 0.000], 0.32±0.11μm [P 0.003] in WO and TOSCA groups respectively. Average tissue ablation was 79±16 μ and 66±17 μ in two respectively.
Although both wavefront-optimized and topography-guided LASIK provided excellent refractive correction results, nonetheless the topography guided LASIK was associated with better visual results in terms of better uncorrected visual acuity, induction of fewer higher-order aberrations and ablated lesser corneal stroma in normal virgin myopic eyes.