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

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PURPOSE. This study measures the effect of moderate and severe levels of diabetes 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 250 g rats (Harlan Sprague Dawley) with streptozotocin (35 and 55 mg/kg body weight iv). Animals were 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 rats were also sacrificed at 7 or 12.5 weeks. Lenses removed from animals were analyzed in terms of average focal length (mm), focal length variability (spherical aberration, mm) and relative transmission of light (scatter or number 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 weeks, as indicated by an increase in focal length variability (FLV). This was true for control and fructose diets. For example, after 12.5 weeks on the diets average FLV 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 = 10], 0.95 ± 0.11 mm [n = 9], (control and fructose diets, severe diabetes), were measured. The difference between control and fructose diets was significant at 12.5 weeks in the severe diabetes group (p = 0.009). CONCLUSIONS. A high fructose diet results in more lens damage in severely diabetic rats over time than a control (glucose/ cornstarch) diet, as quantified optically using a laser scanning system.