Abstract
Purpose: :
To determine whether progressive retinal microangiopathic changes in the galactosemic rat (GR) can be topographically correlated with adjacent choriopathic changes. Interdependence for oxygenation between the outer retina and the choroid can promote localized hypoxia to the retina in regions where there is underlying choriopathy.
Methods: :
Male SD rats were randomized into groups fed ad lib either 50% starch (control) or 50% D-galactose for up to 12 months. Rats received a 370C heparinized saline flush followed by 2000kD FITC-dextran (50mg/ml) retrograde cephalic perfusion at 250mm Hg. Evaluation of retinal and choroidal vascular changes was accomplished using whole flat-mounted samples. Full-thickness optical scanning of multiple regions of the tissue was conducted with a Zeiss 510 laser confocal microscope. Retinal arterioles, venules, capillary layer, choriocapillaris and larger choroidal vessels were evaluated by three dimensional image reconstructions (Zeiss and Metamorph software).
Results: :
The majority of retinal microangiopathic changes were observed in the mid-retinal region. Progressive retinal vascular changes in the GRs included increased vessel tortuosity, venous beading, capillary dilation, and dilated meshworks. Regions of compromised perfusion were observed in the deep capillary plexus of the retina. Vascular anomalies in the choroid were less discernable than in the retina. Changes in vessel diameter were noted in the GR choroidal vasculature. Control rats did not exhibit appreciable retinal or choroidal vascular changes.
Conclusions: :
These data are the first to temporally and topographically correlate progressive retinopathy in the GR model with changes in the choroidal vasculature. The existence of choroidal vasculopathy in regions adjacent to retinal microangiopathy suggest that the choroid could contribute and exacerbate the progression of retinopathy. The data highlights the merit of conducting both retinal and choroidal examinations when monitoring and evaluating patients for diabetic ocular complications.
Keywords: diabetic retinopathy • imaging/image analysis: non-clinical • choroid: neovascularization