Spherical aberration and binocularity

Abstract

AbstractPurpose To evaluate the effect of different combinations of spherical (SA4) and secondary spherical (SA6) aberration on each eye on binocular subjective quality of vision.Methods A numerical eye model was used to generate images (ie three 0.4 logMAR high contrast letters) viewed through a 4.7mm pupil diameter and degraded by various spherical aberrations (SA4‐0.4μm, SA4+0.4μm, SA4‐0.4μm and SA6+0.2μm, SA4+0.4μm and SA6‐0.2μm). Binocular vision was simulated using a 3D‐NVIDIA video system projecting different image on each eye. Through‐focus quality of vision was evaluated using a grading scale (ITU‐R 500 recommendation) by three subjects under monocular and binocular condition for each tested conditions (ie various combination of the five aberration profiles).Results Binocular through‐focus curve followed the best monocular curve. Binocular inhibition was obtained if subjective image quality was too different between the two eyes. We rarely measured binocular summation in term of subjective quality of vision. Ocular dominance seemed to affect the level of inhibition: binocular inhibition was limited when the dominant eye saw the best image. Area under the binocular curve (ie a way to evaluate subjective depth‐of‐focus) measured for a fair or higher image quality was increased with all combinations compared to naked eye because of the summation of the two best monocular curves. The greatest increase was obtained with reverse profile of SA4 and SA6 between each eye (ie SA4‐0.4μm and SA6+0.2μm on one eye and SA4+0.4μm and SA6‐0.2μm on the other eye).Conclusion The use of different spherical aberration on each eye leads to a better binocular through‐focus curve especially with combination of opposite sign of SA4 and SA6. However there is no binocular summation of vision quality.