Abstract
Purpose: :
To evaluate stereoscopic vision after LASIK and the role of post-surgical interocular differences in higher-order eye aberrations, corneal asphericity, and initial anisometropia.
Methods: :
We measured maximum disparity with a mirror stereoscope pre-(best-corrected) and after LASIK for 30 patients. Their mean pre-operative spherical refractive error was -4.7±2.0 D, ranging from -1.0 to -8.0 D. Data on aberrometry were taken with a WASCA aberrometer. Corneal shape data were provided by a corneal topographer. For each patient, the anisometropia was computed as the difference between the spherical equivalent of each eye.
Results: :
The results showed that stereoscopic vision is less effective after LASIK, since for 93% of the patients, maximum disparity diminished. This lower maximum disparity implies a reduction in the physical region where stereoscopic perception occurs and thus in the quality of stereopsis. We also found that the larger the interocular-differences in post-surgical corneal asphericity the less effective the stereopsis (r=0.82, p<0.01); on the other hand, the greater the differences in the higher-order aberrations, the worse the quality of stereoscopic vision (r=0.85, p<0.01). Analyzing pre-LASIK anisometropia we found that maximum disparity diminishes for increasing values of initial anisometropia (r=0.87, p<0.01).
Conclusions: :
Our results indicate that stereopsis deteriorates after LASIK. Ablation algorithms should minimize interocular-differences (aberrations and corneal aasphericity) to avoid a decrease in binocular visual performance.
Keywords: binocular vision/stereopsis