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Meznah S Almutairi, Basal Altoaimi, Arthur Bradley; Static and Dynamic Accommodation and Pupil Responses of Early Presbyopes Viewing through Monovision Corrections. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3963. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Monovision is widely used for correcting presbyopia, and often prescribed to emerging presbyopes with residual accommodation. To evaluate the impact of monovision on retinal image quality, we measured the accommodation and pupil behavior of emerging presbyopes viewing through monovision corrections.
Using a high resolution Shack-Hartmann aberrometer, we measured minimum RMS and paraxial refractive states as binocularly viewed 20/40 characters were moved from 2m to 20cm and back again in 0.25D increments at low photopic light levels in a sample of 10 presbyopic and pre-presbyopic subjects. Distance and near corrected eyes viewed through their distance Rx or a +2D add lens, respectively. Dynamic accommodative responses were measured as stimuli jumped from the distance to the near retinal conjugate planes (a +2D step). Binocular distance and binocular near corrections were used as controls.
With bilateral near corrections, subjects refrained from accommodating until the target was closer than 50 cm. As targets came closer than the far point, some early presbyopes accommodated accurately until their maximum accommodation amplitude was reached, while others responded over a large dioptric range but with a small proportion of the accommodation necessary to focus the stimulus (paraxial accommodative gains ranged from 0.665 to 1.238 and 0.903 to 1.191 with monovision and SV, respectively). Even without accommodation, convergence pupil miosis was typical, but variable (0.225 ± 0.199 mm/D). With monovision, early presbyopes (n=7, age <44) typically accommodated to focus the distance corrected eye, but other early presbyopes (ages=37-40) switched from focusing with the distance corrected eye to the near corrected eye as target distance is reduced. When a target is abruptly stepped from the distance to near retinal conjugate planes, most subjects accommodated even though no accommodation was required to retain focus.
The majority of pre-presbyopes who accommodated >3D maintained the distance corrected eye well focused over their full range of accommodation. Those with more limited accommodation adjust their focusing behavior to optimize image quality in the distance and the near corrected eyes as target distance is reduced. This switching behavior in early presbyopes maximized the dioptric range of high quality retinal images.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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