Absence of cone mediated retinal pathways increases susceptibility to form-deprivation myopia in mice

Ranjay Chakraborty

Abstract

Purpose: We have previously shown that functional rod photoreceptors are critical to visually driven ocular growth in mice. In this study, we examined the contribution of cone mediated retinal pathways to normal refractive development and to visual form-deprivation (FD) in a mouse model lacking functional cone photoreceptors (Gnat2-/-).

Methods: Refractive development of Gnat2-/- and age-matched wild-type (WT) mice, were measured every 2 weeks from 4 to 14 weeks of age. Weekly measurements were performed on a separate cohort of mice that underwent monocular FD in the right eye from 4 weeks of age using head-mounted diffuser goggles. Refraction, corneal curvature, and ocular biometrics were obtained using photorefraction, keratometry and spectral-domain optical coherence tomography.

Results: Under normal visual conditions, both Gnat2-/- and WT mice showed a significant increase in hyperopic refraction with age (p < 0.001). However, the pattern of refractive development was similar between the two genotypes across age (mean refractive error ± SEM at 10 weeks, Gnat2-/- :+5.74 ± 0.56 D, WT: +6.57 ± 0.78 D, p = 0.296). Both axial length and corneal radius of curvature increased significantly with age (p < 0.001); however, they were not significantly different between the two genotypes during development (p > 0.05). Three weeks of FD treatment produced a significantly greater myopic shift in Gnat2-/- mice compared to WT controls (-5.40 ± 1.33 D vs -2.47 ± 0.29, respectively; p < 0.04).

Conclusions: These findings suggest that cone pathways, which are needed for high acuity vision in primates, are not so critical for normal refractive development, but important for the development of FD myopia in mice. Differences in the pattern of refractive development between Gnat2-/- mice and mice with non-functional rods (Gnat1-/-, Park et al, 2014) suggest that rod and cone pathways may differentially modulate refractive development under different visual conditions. 

Details

Year: 2016

Program Number: 160074

Resource Type: Scientific Program

Author Affiliation: n/a

Co-Authors: Han na Park, Erica Landis, Michael Bergen, Li He, Paul Iuvone, Machelle Pardue

Co-Author Affiliation: Atlanta VA Medical Center, Decatur, GA, Emory University School of Medicine, Atlanta, GA, Atlanta VA Medical Center, Decatur, GA, Emory University School of Medicine, Atlanta, GA, Emory University School of Medicine, Atlanta, GA,, Georgia Institute of Technology, Atlanta, GA,

Room: 212 AB