Age-dependent lens changes in galactose-fed dogs

Aldose reductase initiated sugar cataract formation in 9-month old galactose-fed dogs has been documented to progress from an accentuation of lens sutures (1 month after initial feeding) to the appearance of cortical vacuoles (3 months), cortical opacities (4-6 months) and eventually the progressive formation of a clear zone at the cortical equatorial regions of the cataractous lenses (> 12 months). Here, the effect of age on the onset and degree of sugar cataract formation has been investigated in beagles fed a 30% galactose diet starting at 2, 6, and 24 months of age. Cataract formation was monitored by slit lamp and retroillumination microscopy. Compared to 9-month old dogs, cataract formation in the younger dogs was more rapid and the lens changes were more severe. In the 2-month old group of dogs, galactose-feeding resulted in a rapid formation of dense cataracts which began to resorb after 106 days of galactose feeding with only opaque nuclear remnants remaining after eight months. These changes were mirrored by age-dependent reductions of lenticular NADPH-dependent reductase activity.