Timing of the Protective Effect of Photopic Lighting on Treating Myopia
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Hogan, Kelleigh
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Abstract
Purpose. Photopic lighting reduces myopia severity in animal and human studies. However, the causal relationship identified in past animal studies have pre-treated the animals with photopic lighting prior to myopia inducement. This study aims to determine if the protective effect of photopic light is sustained when treatment occurs after myopia inducement.
Methods. C57BL/6J mice were randomized into three groups: photopic lighting starting at post-natal day 23 (pre-treatment), photopic lighting starting at post-natal day 30 (post-treatment) or mesopic lighting throughout the experiment. Myopia was introduced in a subset of mice at post-natal day 28 through the placement of a negative lens over the right (OD) eye. Photorefraction, keratometry, and optical coherence tomography measurements were taken at baseline prior to goggling and at 1- and 2-weeks post-goggling. Refractive development was assessed by analyzing treated eye values and calculating the myopic shift. Retinas were collected at post-natal day 44, for HPLC quantification of dopamine and DOPAC levels.
Results. Pre-treatment with photopic lighting significantly decreased the myopic shift with lens-induced myopia (LIM) compared to post-treatment photopic lighting and mesopic lighting groups. No significant differences were found in ocular parameters, and HPLC analysis has not been conducted on retinas.
Conclusions. Pre-treatment with photopic lighting was confirmed by this experiment. Importantly, LIM animals undergoing post-treatment with photopic lighting condition showed similar susceptibility to LIM as those in the mesopic lighting group. These findings suggest that the protective effect of photopic light requires a pre-conditioning period to alter susceptibility to LIM
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Date
2020-05
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Text
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Undergraduate Thesis