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 establish a rabbit model of myopia based on photorefractive keratectomy (PRK)-induced anisometropia.

METHODS

A group of five pigmented rabbits was treated 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 pigmented rabbits was treated with a monocular -6 D PRK at 10 weeks of age. Longitudinal 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.

RESULTS

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 +/- 0.45 mm vs 15.45 +/- 0.56 mm). In group 2, the PRK-treated eyes were significantly longer by 0.19 mm and 0.20 mm at ages 19 and 21 weeks, respectively.

CONCLUSIONS

PRK-induced anisometropia is an effective technique to induce hyperopic error compensation in the rabbit as a model of myopic development. The technique is effective if the PRK procedure is performed at either 5 or 10 weeks of age. However, after PRK at 5 weeks of age, partial retreatment may be necessary due to regression of the PRK effect.