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Derek Nankivil, Ben Wooley; A Neuro-Optical Model of Binocular Visual Performance in Simultaneous Vision. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3056.
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© ARVO (1962-2015); The Authors (2016-present)
Optical and visual performance models in the literature have failed to capture the myriad environmental conditions and subject qualities that influence the patient’s visual experience. To address this, we developed a model of visual acuity (VA) and used it to examine the performance of simultaneous vision contact lens designs.
The general functional form of subjective image quality is given by k*INT(MTF(υ)*W(υ)dυ) where k is a constant, MTF(υ) is the modulation transfer function of the optical system, and W(υ) is a weighting function, which captures the sensitivity of the retina/brain to certain spatial frequencies, υ. This model was calibrated to optimize the correlation with measured VA data obtained on subjects wearing various multifocal contact lens designs using all pertinent data available in the literature (>10,000 subjects). The model includes the age, refraction and accommodation dependence of the spherical aberration of the eye, the luminance, age, and refraction dependence of the ocular pupil, age-dependent accommodative loss, and accommodative lag. Binocular summation/inhibition was modeled considering the neural integration of monocular signals from each eye. Binocular VA was modeled across add levels of 0.75 to 2.5D, refractive errors of -9 to 6D, vergence demands of 0 to 2.5D, and luminance levels of 1 to 7,000 cd/m2. Two potential multifocal contact lens designs were evaluated and compared.
Binocular VA was ≥-1 (-10logMAR) for all refractive errors with luminance ≥150 cd/m2 for add levels of 1, 1.75 and 2.5D over vergence ranges of 0 to 2.3D, 0.4 to 2.1D, and 0.2 to 2D, respectively, for design 1 and 0 to >2.5D, 0.2 to 2.3D, and 0.1 to 1.7D, respectively, for design 2. For add powers ranging from 0.75 to 1.75D, design 2 was superior over a vergence range of ~2 to 2.5D, while design 1 was superior in low luminance with a 1D vergence. For add levels ranging from 2 to 2.5D, design 2 is superior at low luminance with a distance target, while design 1 is superior, at moderate and high luminance, particularly for myopes, over a vergence range of ~2 to 2.5D.
A neuro-optical model of VA was developed and applied to the assessment of multifocal contact lens designs. The model illustrates the manner in which multifocal designs require performance trade-offs across the manifold of subject/environment space.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Visual Performance: Design 1 (top) and design 2 (bottom) with a 1D add.
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