PRK-induced anisometropia in the rabbit as a model of myopia

Background: Current animal models of myopia, such as the chick and the tree shrew, have characteristics that limit their applicability to human myopia and/or their use among researchers. The purpose of this study was to estab lish a rabbit model of myopia based on photorefractive keratectomy (PRK)-in duced anisometropia. a Methods: A group of five pigmented rabbits was treat ed with a monocular -5 D PRK at 5 weeks of age. At 10 weeks of age, two of the eyes were retreated with a second -5 D PRK procedure to compensate for partial regression of the refractive effect. A second group of six pigmente d rabbits was treated with a monocular -6 D PRK at 10 weeks of age. Longitu dinal measurements of corneal curvature, refraction, and axial length were performed until the rabbits were 13 and 21 weeks of age in groups 1 and 2, respectively. The rabbits in each group were from the same litter. a Result s: Keratometry and retinoscopy measurements confirmed the refractive effect of the PRK procedures. At the final measurement point in group 1, the PRK- treated eyes were significantly longer than the untreated eyes (16.01+/-0.4 5 mm vs 15.45+/-0.56 mm). In group 2, the PRK-treated eyes were significant ly longer by 0.19 mm and 0.20 mm at ages 19 and 21 weeks, respectively, a C onclusions: PRK-induced anisometropia is an effective technique to induce h yperopic error compensation in the rabbit as a model of myopic development. The technique is effective if the PRK procedure is performed at either 5 o r 10 weeks of age. However, after PRK at 5 weeks of age, partial retreatmen t may be necessary due to regression of the PRK effect.