Amplitudes of accommodation of primate lenses refilled with two types of inflatable endocapsular balloons
O. Nishi, Y. Nakai, Y. Yamada and Y. Mizumoto
Jinshikai Medical Foundation, Nishi Eye Hospital, Osaka, Japan.
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 non-accommodated 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 +/- 0.9 D, 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.
