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J. P. McDonald, M. Croft, J. Ben-nun, G. Heatley, P. L. Kaufman; Nulens Expermental Accommodating IOL in the Primate Eye. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3143.
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© ARVO (1962-2015); The Authors (2016-present)
To test a new concept of an accommodating experimental intraocular lens (IOL) and evaluate its characteristics following implantation in one eye and a force measuring device in the opposite eye of two rhesus monkeys.
Total iridectomy was performed in both eyes of 2 rhesus monkeys (Macaca mulatta). Subsequently, a bipolar stimulating electrode was implanted into the Edinger-Westphal (E-W) nucleus of the brain. Prior to IOL insertion, the ciliary body (CB) and lens functions were evaluated by Scheimpflug photography, color slit-lamp photography, ultrasound biomicroscopy (UBM) and goniovideography (GV) in both monkeys (6 years old). A Hartinger coincidence refractometer was used to measure resting refractive error and accommodation. The IOL inserted OD incorporates a small chamber of silicone gel and a posterior piston with a round aperture in its center that allows the compressed gel to bulge relative to the pressure applied to it by the capsular diaphragm. The IOL is placed in front of the capsular diaphragm and internally anchored without sutures to the ciliary sulcus by the specially designed haptic. The mechanism of the force measuring device implanted OS mimics the mechanism of the NuLens IOL. Both eyes with IOLs had large posterior capsulotomy and vitrectomy.
Accommodation induced by direct electrical stimulation of the E-W nucleus occurred in one eye with the NuLens IOL (8.25 diopters of accommodation (D) at 4 months and 5 D at 6 months, respectively). Contraction of the capsular diaphragm was noted. The opposite eye was clear and the force gauge showed movement range of 500 µm at 9 months post insertion, but capsular contraction was noted causing a shift of the force gauge baseline.
The NuLens IOL can generate substantial accommodation, and the force gauge remains fully functional in response to central stimulation for at least 6-9 months after implantation in the monkey eye. Deterioration in IOL function seems to be directly related to capsular contraction. Readjustment of IOL position may restore the original functional range. Additional IOL implantations in rhesus monkeys are scheduled for January 2007.
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