Amplitudes of Accommodation of Primate Lenses Refilled With Two Types of Inflatable Endocapsular Balloons

Abstract

Objective: To investigate the maintenance of ocular accommodation by refilling the lenses of the eyes of youthful primates with inflatable endocapsular balloons. Methods: The lenses of 21 cynomolgus monkeys were refilled following endocapsular phacoemulsification with a balloon that either approximates the shape of the nonaccommodated lens or the accommodated crystalline lens. Results: In nine of 15 successfully refilled lenses, we were able to perform automated refractometry to determine the amplitude of accommodation, ie, changes in refraction before and 1 hour after application of topical 4% pilocarpine hydrochloride to alter lens shape. At 2 weeks, 2 to 3 months, and 6 to 12 months after operation, mean (±SD) accommodation was 4.6±2.5, 2.5±0.5, and 1.7±0.7 diopters (D), respectively, in the lenses refilled with the nonaccommodation balloon (n=5; preoperative value, 15.2±1.3 D), and it was 1.9±0.5,1.3±0.9,and 1.8±0.9D, respectively, in the lenses refilled with the accommodation balloon (n=4; preoperative value, 17.0±2.9 D). Conclusion: The greater yield of accommodation with the nonaccommodation balloon is consistent with the recent theory on the mechanism of accommodation. Although the obtained accommodation was a small fraction of values determined prior to the operation and the small amplitude of accommodation decreased over time, the feasibility of refilling the lens with an inflatable endocapsular balloon, allowing at least some accommodation in the eyes of youthful primates, was demonstrated. Applied to humans, this procedure may allow accommodation following cataract surgery.