Effect of diabetes and fructose/non-fructose diet on the optical quality (cataracts) of the rat lens

Purpose. This study measures the effect of moderate and severe levels of di abetes on the optical performance of the rat lens, and evaluates the effect of dietary fructose on diabetic lens damage. Methods. Moderate and severe diabetes were induced in 250g rats (Harlan Spr ague Dawley) with streptozotocin (35 & 55 mg/kg body weight iv). Animals we re fed either a control (glucose/cornstarch) or a 40% (wt:wt) fructose and cornstarch diet and then sacrificed after 7 or 12.5 weeks. These two diets were also fed to two groups in which diabetes was, not induced and these ra ts were also sacrificed at 7 or 12.5 weeks. Lenses removed from animals wer e analyzed in terms of average focal length (mm), focal length variability (spherical aberration, mm) and relative transmission of light (scatter or n umber of pixels excited by a refracted laser beam) using an automated laser scanning system. Results. Diabetes disrupted rat lens optical function, both at 7 and 12.5 w eeks, as indicated by an increase in focal length variability (FLV). This w as true for control and fructose diets. For example, after 12.5 weeks on th e diets average FLY values of 0.10 +/- 0.00 mm [n = 9], 0.11 +/- 0.01 mm [n = 9],(control and fructose diets, no diabetes) and 0.48 +/- 0.04 mm [n = 1 0], 0.95 +/- 0.11 mm [n = 9], (control and fructose diets, severe diabetes) , were measured. The difference between control and fructose diets was sign ificant at 12.5 weeks in the severe diabetes group (p less than or equal to 0.009). Conclusions. A high fructose diet results in more lens damage in severely d iabetic rats over time than a control (glucose/cornstarch) diet, as quantif ied optically using a laser scanning system.