Abstract
Purpose: :
To investigate whether long-term visual experience with irregular optical blur compensates for the impact of higher order aberration on visual performance in keratoconic (KC) eyes. This was achieved by comparing visual performance in KC eyes, and normal eyes viewing through KC aberrations
Methods: :
Aberrations, high (100%) and low (20%) contrast tumbling ‘E’ visual acuity were measured in 4 moderate KC eyes wearing soft toric contact lenses, over a 6-mm pupil. Same 3 emmetropic normal eyes were recruited to measure visual acuity with each of 4 KC eyes’ aberration and the results were compared with those from the KC eyes. An adaptive optics system was used to correct the normal eye’s aberration and induce KC eye’s aberrations on them simultaneously during vision testing. Neural compensation was defined as the improvement in visual acuity in each KC eye compared to the 3 normal eyes with KC aberrations.
Results: :
Mean total and higher order rms errors in the KC eyes with their contact lens were 2.72±0.83 µm and 1.36±0.29 µm for a 6 mm pupil, respectively. Rms wavefront error in induction of KC aberrations on normal eyes was around 0.1 µm in all cases. Each KC eye had statistically better high (p<0.02) and low (p<0.03) contrast visual acuity than the 3 normal eyes. Mean compensation for high contrast visual acuity in logMAR was 0.12±0.09, corresponding to an improvement of 23.8 %. A similar result was obtained for low contrast visual acuity also .The magnitude of compensation increased with the severity of KC aberrations.
Keywords: aberrations • keratoconus • adaptation: blur