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Effects of low intensity ambient lighting on refractive development in infant rhesus monkeys (Macaca mulatta)
Zhihui She1, Li-Fang Hung2, Baskar Arumugam1
1College of Optometry, University of Houston, Houston, TX, United States.
Insights
Low intensity ambient lighting did not cause myopia in infant rhesus monkeys. Instead, dim light exposure led to hyperopia and sustained choroidal thickening, suggesting it may impair normal refractive development.
Area of Science:
- Ophthalmology
- Primate Research
- Vision Science
Background:
- Studies in chickens suggest low-intensity ambient lighting can induce myopia.
- The effect of dim light on refractive development in primates remains unclear.
Purpose of the Study:
- To investigate the impact of low-intensity ambient lighting (dim light) on refractive development in infant macaque monkeys.
- To determine if dim light exposure influences myopia development or other ocular parameters in primates.
Main Methods:
- Seven infant rhesus monkeys were reared under dim light (~55 lx) from 24 to 310 days of age.
- Ocular parameters including refractive error, corneal power, axial dimensions, and choroidal thickness were measured periodically.
- Measurements were compared to those of age-matched monkeys reared under normal light conditions.
Main Results:
- Dim light rearing did not induce myopia; instead, monkeys exhibited hyperopia compared to normal-light controls.
- Significant sustained thickening of the choroid was observed in dim-light-reared monkeys.
- Corneal power development and axial dimensions were not altered by dim light exposure.
Conclusions:
- Low ambient lighting alone is not necessarily myopiagenic in rhesus monkeys.
- Dim light exposure may compromise the efficiency of emmetropization in primates.
- Further research is needed to understand the long-term effects on visual development.
Abstract:
Studies in chickens suggest low intensity ambient lighting causes myopia. The purpose of this experiment was to examine the effects of low intensity ambient lighting (dim light) on normal refractive development in macaque monkeys. Seven infant rhesus monkeys were reared under dim light (room illumination level: ~55 lx) from 24 to ~310 days of age with otherwise unrestricted vision. Refractive error, corneal power, ocular axial dimensions, and choroidal thickness were measured in anesthetized animals at the onset of the experiment and periodically throughout the dim-light-rearing period, and were compared with those of normal-light-reared monkeys. We found that dim light did not produce myopia; instead, dim-light monkeys were hyperopic relative to normal-light monkeys (median refractive errors at ~155 days, OD: +3.13 D vs. +2.31 D; OS: +3.31D vs. +2.44 D; at ~310 days, OD: +2.75D vs. +1.78D, OS: +3.00D vs. +1.75D). In addition, dim-light rearing caused sustained thickening in the choroid, but it did not alter corneal power development, nor did it change the axial nature of the refractive errors. These results showed that, for rhesus monkeys and possibly other primates, low ambient lighting by itself is not necessarily myopiagenic, but might compromise the efficiency of emmetropization.
