Abstract
Abstract: :
Background:Because of its similarity to the human eye and long history of use in the evaluation of ocular conditions and reactivity, the rabbit is considered the animal model of choice for the preclinical evaluation of new ocular pharmaceuticals and devices. The present studies evaluated the utility of the rabbit model in assessing potential accommodating IOLs. Purpose: To develop an animal model for the assessment of potential accommodating IOLs. Methods: A series of intraocular lens studies were conducted in Dutch Belt pigmented and New Zealand white rabbits of varying ages. The phakic, aphakic and pseudophakic (silicone disc IOL) rabbit eye was evaluated before and after application of carbachol 2.25% administered topically and by iontophoresis. Accommodative response was evaluated by measuring changes in anterior chamber (AC) depth on Scheimpflug photographs and by A–scan biometry. Results: Scheimpflug analysis revealed an accommodative response to carbachol only in the very young (age 6 weeks) phakic rabbit (mean decrease in anterior chamber depth = 0.3 mm), the young (10 weeks) aphakic rabbit (0.47 mm) and adult (12 months) aphakic rabbit (0.42 mm) . An accommodative response was also noted in the young adult (0.3 mm) and adult (0.4 mm to 0.6 mm) pseudophakic rabbit (11 mm silicone disc IOL) . A–scan biometry detected a greater decrease in anterior chamber depth with carbachol stimulation than Scheimpflug analysis measured. Mean anterior chamber depth decreased in the young adult aphakic rabbit (0.61 mm) and adult aphakic rabbit (1.10 mm), and in the young (0.63 mm), young adult (0.58) and adult (0.57 mm) pseudophakic rabbit (11 mm silicone disc IOL) . Conclusion:An accommodative response was seen in the rabbit aphakic and pseudophakic eye in response to stimulation with 2.25% carbachol, as measured by changes in anterior chamber depth with Scheimpflug photography and A–scan biometry. This rabbit model may be used to assess the axial movement of potential accommodating IOLs. However, the relationship of the accommodative response to carbachol to the natural accommodative response is not known.