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Development of acuity in a primate model of human infantile unilateral aphakia
C D O'Dell1, J A Gammon, A Fernandes
1Yerkes Regional Primate Research Center, Emory University, Atlanta, GA 30322.
Insights
Infantile unilateral aphakia in monkeys shows that correcting the aphakic eye is crucial for vision development. Occluding the other eye should be used cautiously to avoid vision loss.
Area of Science:
- Ophthalmology
- Developmental Biology
- Primate Models
Background:
- Infantile unilateral aphakia can lead to severe visual impairment.
- Understanding visual development in aphakia is critical for timely intervention.
Purpose of the Study:
- To investigate the impact of different optical corrections and occlusion strategies on visual acuity development in infant rhesus monkeys with unilateral aphakia.
- To model infantile unilateral aphakia to determine optimal treatment approaches.
Main Methods:
- Infant rhesus monkeys were reared under various deprivation conditions to model unilateral aphakia.
- Grating acuity was assessed from birth to approximately 1 year using the quick acuity card procedure.
- Different optical corrections (uncorrected, undercorrected, near-point correction) and occlusion methods (continuous, partial, none) were applied.
Main Results:
- An uncorrected aphakic eye developed minimal to no pattern vision.
- Near-point correction with extended-wear contact lenses and contralateral eye occlusion sometimes normalized acuity in the aphakic eye but caused vision loss in the occluded eye.
- Fifty percent partial occlusion with near-point correction led to similar acuity development in both eyes.
- Near-point correction alone in the aphakic eye resulted in surprisingly good residual acuities.
Conclusions:
- Optical correction for aphakic eyes is essential for visual development.
- Contralateral eye occlusion should be employed cautiously in treating unilateral aphakia due to potential vision loss.
- Near-point correction without occlusion shows promise for maintaining residual acuity in aphakic eyes.
Abstract:
We are studying infant rhesus monkeys that have been reared under various conditions of deprivation to model infantile unilateral aphakia. Grating acuity was assessed in these monkeys from birth to approximately 1 year of age using the quick acuity card procedure. We found that an uncorrected aphakic eye develops little or no pattern vision. Undercorrection or near point optical correction of an aphakic eye with an extended-wear contact lens coupled with continuous occlusion of the opposite eye sometimes results in normal development of acuity in the aphakic eye but does so only at the cost of loss of vision in the occluded eye. Fifty percent partial occlusion coupled with near-point correction of the aphakic eye results in similar development of acuity for both eyes during the time tested. Monkeys wearing near-point correction in the aphakic eye and without any occlusion of the other eye show surprisingly good residual acuities in their aphakic eyes. Based on these results we conclude that aphakic eyes should be treated by providing them with an optical correction, and that occlusion of the opposite eye should be used cautiously.