Abstract
Purpose: :
The purpose of this study was to evaluate the changes in visual acuity (VA) measurements and visual perception generated by correcting higher-order aberrations (HOA) in keratoconus eyes using a large stroke adaptive optics visual simulator.
Methods: :
We used a crx1 adaptive optics visual simulator (Imagine Eyes, France), based on a Shack-Hartmann sensor and an electromagnetic deformable mirror operating in closed-loop, to correct and modify the wavefront aberrations in 12 keratoconus eyes (8 patients). After measuring ocular aberrations, we programmed the device to compensate for the eye’s wavefront error alternately up to the second order and up to the fourth orders using a 6-mm artificial pupil. We assessed VA through the adaptive optics system using computer-generated ETDRS optotypes and Landolt C test (Fract test) displayed at the internal miniature monitor. The patients were asked to draw on paper their visual perception of the ETDRS letters presented with each correction.
Results: :
The mean total RMS and HOA RMS in the keratoconus eyes over a 6-mm pupil were 3.88±2.22µm and 1.88±0.99µm respectively; defocus 2.64±2.88µm; coma 1.25±0.90µm and spherical aberration 0.70±0.46µm. The visual simulator correction of the aberrations present in the patients' eyes improved their visual acuity by a mean of 2 lines (0.18 LogMAR on average), when compared to their best sphero-cylinder correction (mean decimal VA from 0.31 with sphero-cylinder-order correction, 0.44 with custom-wavefront correction). The visual perception of ETDRS letters was strongly improved when correcting higher-order aberrations.
Conclusions: :
The electromagnetic adaptive optics visual simulator was able to correct large amounts of 2nd to 4th order aberrations in highly aberrated eyes. Even severe keratoconus patients showed improved visual performance under custom-wavefront correction compared to best-spectacle correction. Adaptive optics technology may find a clinical interest in demonstrating the maximum potential for visual correction improvement and neuroadaptation.
Keywords: refractive surgery: optical quality • aberrations • keratoconus