Abstract
Purpose: :
To improve through-focus visual performance with modified monovision by monocularly inducing spherical aberration.
Methods: :
A binocular adaptive optics (AO) system was used to correct both eyes’ aberrations and induce spherical aberration in the non-dominant eye for a 4mm pupil. Three conditions, traditional monovision (TMV) and 2 cases of modified monovision, were tested by measuring binocular high contrast visual acuity (VA) in white light through-focus (0.5D increments) in 3 subjects (age: 43+15 years). The native aberrations of both eyes were corrected in each subject with AO. TMV was simulated by inducing 1.5D of anisometropia with the dominant eye refracted for distance and non-dominant eye refracted for near. Two modified monovision cases were simulated by inducing 0.2µm (MMV1) and 0.4µm (MMV2) of SA in the non-dominant eye with the anisometropia held at 1.5D. Monocular through-focus VA was measured in the non-dominant eye in three conditions after correcting all aberrations and inducing 0, 0.2µm and 0.4µm of SA, respectively. The depth of focus was estimated as the dioptric range over which VA was greater than 0.18 logMAR corresponding to 20/30 Snellen acuity.
Results: :
VA at 0D and 1.5D was similar between the three monovision conditions (p<0.05). For intermediate vision at 1.0D, MMV1 and MMV2 improved VA (-0.23+0.04 and -0.17+0.03 logMAR, respectively) as compared to TMV (-0.05+0.01 logMAR). For near vision at 2.5D, MMV1 and MMV2 improved VA (-0.02+0.00 and -0.14+0.01 logMAR, respectively) as compared to TMV (0.05+0.02 logMAR). The depth of focus was also extended in MMV1 and MMV2 (3.3+0.6D and 4.2+0.3D, respectively) as compared to TMV (2.7+0.3D). Monocular through-focus VA was used to obtain a prediction of binocular performance by choosing the superior monocular VA at each defocus position. This predicted binocular through-focus VA was well correlated to measured binocular performance (R2=0.93).
Conclusions: :
In traditional and modified monovision, binocular through-focus visual acuity is well predicted by the acuity of the superior eye. Modified monovision with the induction of spherical aberration in the non-dominant eye improves intermediate and near visual performance, and extends depth of focus without compromising distance visual performance.
Keywords: presbyopia • aberrations • binocular vision/stereopsis