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Antoine Barbot, Ramkumar Sabesan, Tara C Vaz, Deborah S Jacobs, Duje Tadin, Krystel R Huxlin, Geunyoung Yoon; Neural re-adaptation to improved optical quality with customized aberration correction. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2496.
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© ARVO (1962-2015); The Authors (2016-present)
Long-term adaptation to severely degraded optical quality due to large magnitude of ocular aberrations results in visual deficits in neural processing, especially at high spatial frequencies (Sabesan & Yoon 2009; Barbot et al. 2016). Here, we investigated whether neural plasticity induces visual recovery during the passive re-adaptation to improved optical quality.
Two advanced keratoconus subjects (4 eyes) were recruited for the study. Each subject was clinically fitted in both eyes with a PROSE (Prosthetic Replacement of the Ocular Surface Ecosystem) with conventional spherical optics. This lens is similar in principle to a scleral lens except that a customized peripheral haptic aligned with the sclera provides high-positional stability. A custom-developed Shack-Hartmann wavefront sensor was used to assess image rotation and decentration of the lens with respect to the pupil center, and to measure residual aberrations of each KC eye wearing conventional PROSE. Customized PROSE with a wavefront-guided front surface were then designed and manufactured. Residual ocular aberration of each eye and binocular visual performance (acuity and contrast sensitivity) with the custom PROSE were measured for up to 60 hours (KC1) and 27 hours (KC2), allowing us to quantify changes in optical and visual performance over time.
Customized PROSE considerably reduced the amount of residual optical aberrations (RMS right after fitting–conventional: 2.49±1.01 µm; custom: 0.41±0.18 µm). Improved optical quality with the fitted custom PROSE was stable over time (mean variation: .049±.02 µm and .042±.02 µm). Under this stable improved optical quality, both KC subjects showed a significant amelioration in high-contrast visual acuity, by 1.5 lines (0.04 to -0.1 logMAR) and 1.3 lines (-0.02 to -0.15 logMAR), respectively. Contrast sensitivity also improved following PROSE fitting by 2.85±29%, 68.5±1.7% and 80±1.5% at 4, 8, 16 c/deg, respectively.
Passive neural re-adaptation to improved ocular optics helps recover deficits in neural processing imposed by long-term adaptation to large ocular aberrations, suggesting that interactions between optical and neural factors play a major role in visual functions. Future work will focus on further enhancement of this neural re-adaptation process by combining the use of customized vision correction technology with active visual training over longer time periods.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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