Pathological changes in human retinal ganglion cells associated with diabetic and hypertensive retinopathy

Background To examine whether systemic diseases like diabetes and arterial hypertension, which frequently cause retinopathies leading to blindness effect the morphology of retinal ganglion cells (RGC). Methods Histological retina material with a history of being untreated, or laser-coagulated(LC) diabetic retinopathy (DR), or arterial hypertensive retinopathy (AHR) was used. The RGC were labeled by introducing crystals of the fluorescent carbocyanine dye DiI into the nerve fiber layer, which contains ganglion cell axons. Results The typical silhouettes of both major types of RGC, parasol and midget cells, were identified. The axons in DR and AHR retinas showed morphology changes such as irregular swelling and beading. Dendritic field sizes were significantly reduced in RGC of both the hypertonic and diabetic retinas. A significant reduction in branching frequency was evident in both the diabetic and hypertonic retinas, in both the midget and the parasol cells. In LC retinas, both parasol and midget RGC were observed within the LC spots, although their numbers were dramatically decreased compared with normal retinas. Conclusion The data suggest that diabetes and arterial hypertonia have similar effects on the morphology of RGC, in addition to causing microvascular alterations and bleeding. Therefore, therapeutic measures and prognostic outcomes in diabetic and hypertensive retinopathy should also consider regressive changes in retinal neurons.