NEONATAL LENSECTOMY AND INTRAOCULAR-LENS IMPLANTATION - EFFECTS IN RHESUS-MONKEYS

Purpose. To compare the effects of a lensectomy with and without intra ocular lens (IOL) implantation on a neonatal rhesus monkey eye. Method s. A lensectomy and anterior vitrectomy was performed on 75 monkeys du ring the first 16 days of life; 21 of these monkeys also had an IOL im planted into the posterior chamber. The eyes were examined at regular intervals using biomicroscopy, applanation tonometry, and ophthalmosco py. Results. The pseudophakic monkeys were studied until they were 92. 5 +/- 5.8 weeks of age and the aphakic monkeys until they were 80.4 +/ - 5.7 weeks of age. Pupillary membranes (100% versus 55.5%; P < 0.01) and lens regeneration into the pupillary aperture (28.6% versus 5.6%; P = 0.02) occurred more often in the pseudophakic than the aphakic eye s. As a result, the pseudophakic eyes required more reoperations than the aphakic eyes to keep the visual axis clear (P < 0.01). There was n ot a significant difference in the incidence of ocular hypertension be tween the pseudophakic and aphakic eyes (9.5% versus 12.7%; P = 0.34). Pupillary capture of the IOL optic occurred in 52% and haptic breakag e in 33% of the pseudophakic eyes. All of the eyes with broken haptics had a prominent Soemmerring's ring varying in maximum thickness from 0.6 to 2 mm. Nine of the haptics from the seven eyes with broken IOLs had eroded into the iris, two into the ciliary body, and one into the anterior chamber. Conclusions. Implanting an IOL into a neonatal monke y eye after a lensectomy and anterior vitrectomy increases the likelih ood of a reoperation being necessary. Haptics frequently erode into th e iris and ciliary body and may break because of stress placed on the optic-haptic junction by forward movement of the IOL.