Abstract
Presbyopia, the age-related loss of unassisted near vision, is a visual affliction which significantly affects anyone past the age of 40 years. A clinically well-established approach towards correcting presbyopia is monovision. In traditional monovision, the patient's dominant eye (DE) is refracted for distant vision and the non-dominant eye (NDE) for near vision, thus inducing anisometropia. Poor intermediate image quality and monocular suppression of visual input can cause discomfort in presbyopic patients. The goal of this study is to improve binocular through-focus visual performance and extend the depth-of-focus (DOF) by inducing different spherical aberrations (SA) to each of the two eyes. Through-focus high contrast visual acuity in white light was measured in a cyclopleged presbyopic patient (age: 42 years). To simulate traditional monovision, a Badal optometer induced 1.0 diopter of anisometropia in the NDE. For the modified monovision, a binocular adaptive optics system was used to induce four different combinations of SA in each of the two eyes for a 6mm pupil (combination 1: DE-SA=0μm, NDE-SA=+0.5μm; combination 2: DE-SA=0μm, NDE-SA=-0.5mm; combination 3: DE-SA=+0.5mm, NDE-SA=-0.5μm; combination 4: DE-SA=+0.5μm, NDE-SA=+0.5μm). Using 20/30 visual acuity as a DOF threshold criterion, traditional monovision was measured to have a DOF of 3.3 diopters. The modified monovision combinations 1, 2, 3 and 4 exhibited an increase in DOF compared to traditional monovision: 4.4, 3.5, 3.6 and 4.6 diopters, respectively. Modified monovision using SA may have significant potential in enhancing near vision in presbyopia.