Abstract
Purpose: :
Laser vision correction has historically been known to induce spherical aberration in proportion to the magnitude of refractive error treated. We wish to report the visual outcome and change in spherical aberration in the first cohort of eye treated with wavefront optimized femto-LASIK at at refractive surgery center experienced with wavefront guided femto-LASIK.
Methods: :
A retrospective chart review was performed on all patients who underwent refractive treatment using the ALLEGRETTO WAVE 400 platform (AlconLabs, Ft. Worth, TX) between 9/23/2008 aned 7/21/2009 at the Cole Eye Institute. Optimized IntraLASIK was targeted for emmetropia in 160 eyes, and subdivided into mild (<-3.0 D), moderate (-3.1 to -6.0 D) and high myopia (>-6.0 D) and hyperopia. Pre- and 3 months post-operative measures of uncorrected visual acuity (UCVA), and wavefront aberrometry were recorded and compared between groups and in reference to previous wavefront guided IntraLASIK outcomes (CustomCornea, AlconLabs, Ft. Worth, TX).
Results: :
A 20/15 and 20/20 UCVA was achieved in 70% and 93% of eyes with mild myopia (30 eyes), 67% and 90% with moderate myopia (71 eyes), 54% and 94% with high myopia (40 eyes) and 26% and 63% of eyes with hyperopia (19 eyes), respectively. The mean (+/- SD) change in spherical aberration at a 6.5 mm pupil was -0.024 (+/-0.042) um RMS for low myopia (p=0.09), +0.008 (+/-0.079) for moderate myopia (p=0.52), -0.020 (+/-0.067) for high myopia and +0.151 (+/-0.15) for hyperopia (p=0.65), revealing no statistical significance among all wavefront optimized refractive error cohorts. A similar group of myopic wavefront guided cohorts revealed a statistical reduction of spherical aberration in low myopes (p<0.01), but an increase in moderate myopes (p=0.01) and high myopes (p=0.01).
Conclusions: :
Wavefront optimized femto-LASIK with the WaveLight ALLEGRETTO WAVE 400 Hz laser achieves excellent postop UCVA outcomes in this initial surgical experience, with no induction of spherical aberration at all refractive errors. It maintains the natural aspheric shape of the cornea by placement of additional pulses in the midperiphery to compensate for the cosign effect in the angle of incidence of laser pulses.
Keywords: refractive surgery: LASIK • laser • aberrations