Correlation of retinal structure and visual function assessments in mouse diabetes models

PURPOSE. Diabetic retinopathy results in vision loss with changes to both retinal blood vessels and neural retina. Recent studies have revealed that animal models of diabetes demonstrate early loss of visual function. We explored the time course of retinal change in three different mouse models of diabetes in a longitudinal study using in vivo measures of retinal structure (optical coherence tomography [OCT]) and visual function (optomotor and pupillary responses). METHODS. OCT analysis of retinal microstructure, optokinetic response as a measure of visual acuity, and pupillary response to light stimulation were compared among the db/db, Ins2^Akita, and streptozotocin (STZ)-induced mouse models of diabetes at 1.5, 3, 6, and 9 months of diabetes. RESULTS. The db/db, Ins2^Akita, and STZ-induced models of diabetes all exhibited vision loss and retinal thinning as disease progressed. Both structural changes and functional measures were significantly correlated with the blood glucose levels. Despite this, vision loss and retinal thinning were not consistently correlated, except for the inner retinal layer thickness at 6 months of diabetes. CONCLUSIONS. This longitudinal study compiled structural measures and functional outcome data for type 1 and 2 diabetes mouse models commonly used for diabetes studies and demonstrated an overall decline in retinal-related health in conjunction with weight change and blood glucose alterations. The relationship between the structural change and functional outcome could be correlative but is not necessarily causative, as retinal thinning was not sufficient to explain visual acuity decline.