GALACTOSE-INDUCED CATARACT FORMATION IN GUINEA FIGS - MORPHOLOGIC CHANGES AND ACCUMULATION OF GALACTITOL

Purpose. To develop and characterize a new model of galactose-induced cataract formation in young, 3- to 4-week-old Hartley guinea pigs. Met hods. Experimental animals were fed 50% galactose in powdered guinea p ig chow containing 0.5 g ascorbate/kg diet. Control animals were fed n ormal powdered guinea pig chow (0.5 g ascorbate/kg diet). Lenses from all animals were subjected to photo-slit-lamp examination, light micro scopic analysis, and high-pressure liquid chromatography (HPLC) analys is of polyol content. Results. Photo-slit-lamp examination indicated i nitial opacities in equatorial subcapsular region between 3 and 5 days in all galactose-fed animals (20/20); opacities progressed toward the anterior pole when diet was extended to 14 days. Histologic analysis of the equatorial changes confirmed progressive cataract formation con sisting of small intrafibrillar vacuoles in the preequatorial region ( 3 days), an increased number of enlarged and coalesced vacuoles (6 day s), and progressive tissue swellings with cellular disruption and sign s of epithelial multilayering (14 days). The anterior epithelium showe d increased cell height and swelling after 3 days of the galactose die t. HPLC analysis of lens tissue indicated progressive accumulation of galactitol, 18 mM after 3 days, which plateaued to about 30 mM between 6 and 14 days. The level of myo-inositol dropped from a control value of 2.8 +/- 0.7 mM to 1.5 +/- 0.7 mM after 3 days, and was nearly unde tectable after 14 days of the galactose diet. Conclusions. The current study suggests that the guinea pig model may serve as a valuable new tool to study sugar-induced cataract formation and to characterize the early morphologic and biochemical events in cataractogenesis.