Abstract
Purpose: :
We have recently shown in primates that peripheral retinal neurogenesis, as well as overall eye growth, is modulated by the visual input. The purpose of this study was to investigate whether the ocular growth in mice is also modulated by the visual experience and study the role of visual input in overall eye growth, peripheral retinal neurogenesis and refractive eye development in the mouse during early postnatal period.
Methods: :
Small animal MRI, an automated eccentric infrared photorefractor and anti-BrdU immunohistochemistry were used to analyze changes of the refractive state, ocular components and peripheral retinal neurogenesis associated with experimental myopia induced by diffusers in C57BL/6J and Nestin-GFP mice during early postnatal period (P21-P89).
Results: :
21 days of visual form deprivation caused a myopic shift in refraction of 12.0 ± 1.4 D (P = 0.0004) in P24 mice. The derived diameter of the deprived eyes was, on average, 54 ± 9 µm larger (P < 0.0001), and the vitreous chamber depth in the deprived eyes was 45 ± 5 µm longer (P < 0.0001) than in the control fellow eyes. We found a significant number of proliferating progenitors at the retinal periphery in all age groups examined. The proliferation rate was steadily declining with age. The intensity of neurogenesis correlated with the axial eye growth (R = 0.991, P = 0.009). We also found a statistically significant ~2-fold increase (1.91±0.07, P < 0.001, n = 7) in the number of proliferating progenitors in the deprived eyes compared to the control, which correlated with the degree of axial elongation observed in the deprived eyes. We also found that both the degree of axial elongation and the increase in the progenitor cell proliferation index induced by visual form deprivation declined during a critical period in postnatal development that ends around P67.
Conclusions: :
Visual form deprivation under photopic conditions causes axial ocular elongation and development of myopia in mice. Myopia in mice can be induced only during susceptible critical period in postnatal development, which ends around postnatal day 67. The postnatal mouse peripheral retina (similar to the postnatal retina of primates) harbors proliferating neural progenitors. Visual form deprivation in mice causes an increase in peripheral retinal neurogenesis, hence retinal growth, similar to primates. Visual experience can modulate peripheral retinal neurogenesis only during a critical period in postnatal development.
Keywords: myopia • refractive error development • visual development