Lens morphometry determined by B-mode ultrasonography of the normal and cataractous canine lens.

Abstract

PURPOSE: To determine axial lens thickness, anterior chamber depth and axial globe length in canine eyes with normal lenses and in eyes with immature, mature, congenital, posterior polar and diabetic cataract. METHODS: B-mode ultrasonography was performed in 50 normal dogs and, as a prephacoemulsification screening procedure, in 100 dogs with cataract. Axial B-mode ultrasonograms were used to determine lens thickness, anterior chamber depth and globe diameter. Statistical comparisons between groups were made by analysis of variance and multivariate analysis, with a significance level of P < 0.05. RESULTS: Axial globe lengths were not statistically significantly different between groups apart from the smaller globes in younger dogs with congenital cataract. Axial lens thickness in diabetics (8.4 +/- 0.9 mm) was statistically significantly different from the lens thickness in normal eyes (6.7 +/- 1.0 mm), eyes with immature cataract (6.4 +/- 0.8 mm) and eyes with mature cataract (7.4 +/- 0.9 mm) although these groups, while varying in thickness, were not statistically significantly different from each other. Anterior chamber depth was statistically significantly reduced in eyes with diabetic cataract (2.9 +/- 0.1 mm) from that in normal eyes (3.8 +/- 0.1 mm), eyes with immature cataract (3.5 +/- 0.1 mm) and eyes with mature cataract (3.2 +/- 0.6 mm) although these groups, while varying in chamber depth, were not statistically significantly different from each other. CONCLUSIONS: Lenses with diabetic cataracts were significantly increased in axial thickness compared to lenses in other eyes, although lenses with mature cataracts showed a trend towards increased axial thickness and immature cataracts demonstrated a trend towards reduced thickness. While previous studies on cataract pathobiology have suggested a reduction in lens thickness in immature cataract through lens protein loss and an increase in thickness in mature cataracts through intumescence, this study is the first to document these changes in the canine lens.