REFRACTIVE CHANGES INDUCED BY ELECTROCAUTERY OF THE RABBIT ANTERIOR LENS CAPSULE

The pathologic basis for presbyopia is classically attributed to lenti cular sclerosis or atrophy of the ciliary muscle, but recent work sugg ests that thickening and loss of elasticity of the anterior lens capsu le play an important role. As no practical means for attenuating or re versing the aging process of lens protein has been identified, alterat ion of the lens capsule eventually might prove to be a desirable alter native to spectacle correction in presbyopic individuals. This paper d escribes changes in the refractive properties of the lens resulting fr om alteration of the anterior lens capsule by application of focal cau tery, using both an in vitro, in situ and an in vivo rabbit model. In vitro thermal treatment (electrocautery) of the capsule significantly increased the anterior curvature of the lens by an average of +2.95 di opters. Histologic examination of the treated lenses showed thinning o f the capsule in the treated areas, as well as focal vacuolar degenera tion in the lens substance beneath the lesions. In vivo thermal treatm ent of eyes induced a significant shift toward myopia, compared with c ontrol eyes. The accommodative range increased post-treatment relative to the controls, but the effect diminished over time, stabilizing nea r baseline at two to three weeks after treatment. Histologic examinati on showed localized changes but no signs of diffuse cataract formation . We conclude that the anterior capsule may play a significant role in the refractive power and accommodative changes in the crystalline len s. With further study of short-term and long-term effects and with dev elopment of noninvasive laser techniques, thermal treatment of the ant erior lens capsule might eventually become a practical method of manag ing hyperopia and loss of accommodation in patients with advanced pres byopia.