Sarfarazi Elliptical Accommodating IntraOcular Lens (EAIOL) in Rhesus Monkey Eyes In Vitro and In Vivo

Abstract

Abstract: : Purpose: To assess the ability of the Sarfarazi EAIOL (accommodative intraocular lens) to function in excised rhesus monkey eyes and to effect changes in optical power in vivo. Methods: The Sarfarazi EAIOL has an anterior and a posterior optic joined by three spring haptics. in vitro: The Shenasa IOL was inserted into the empty capsular bag of a partially dissected, enucleated rhesus monkey eye after the cornea and sclera were removed. The tissue was glued to a stretching apparatus to radially apply and relax zonular tension. in vivo: In 4 rhesus monkeys (aged 6 to 9 years), cilliary muscle (CM) and lens (natural and IOL) function was evaluated by Scheimpflug photography, ultrasound biomicroscopy (UBM), goniovideography (GV), Hartinger coincidence refractometer and A-scan ultrasound before and after IOL insertion and before and during pharmacological stimulation (CARB; 40% carbachol iontophoresis.) to induce accommodation. Shenasa Focus IOLs were inserted in five eyes. Results: in vitro: The anterior and posterior IOL optics separated when the capsule tension was relaxed. The optics came together when the capsule tension was increased by stretching. The overall IOL thickness increased by as much as 2.13 mm when tension was released. in vivo: Following IOL insertion signs of inflammation included: AC cells, fibrin, and posterior capsule opacification; possibly due to IOL composition, sterilization method or susceptibility of monkeys to inflammation. In one eye with less inflammation (different material and sterilization technique), CARB induced maximum accommodation of 6.25 diopters (D), 7.95 D, and 7.0 D in three separate experiments, and the IOL optics separated compared to pre-CARB baseline by 1.23, 0.34 and 0.13mm, respectively; the anterior chamber shallowed by 0.71, 0.90 and 0.75 respectively. The average accommodation induced by CARB in each experiment was 4.06 diopters (D), 6.12 D, and 5.73 D. The precision of the measured CARB-induced accommodation in the first experiment was compromised by cloudiness of the refractometer mires. Conclusions: The Sarfarazi EAIOL can function as designed, inducing changes in refractive power within the natural lens capsule following extraction of the natural lens substance in vivo if inflammation is controlled.

Keywords: accommodation • aging: visual performance • refraction