Quantitative longitudinal analysis of temporal changes in retinal vessel density and optic nerve head blood flow after optic nerve crush

Glaucoma is associated with ocular blood flow (BF) dysfunction; however, temporal BF changes following neurodegeneration remain poorly understood. We investigated the temporal relationship among these pathological processes using a mouse optic nerve crush (ONC) model. Outcomes included fundus fluorescein angiography (FA) and laser speckle flowgraphy at baseline and days 4, 7, 14, and 28 after ONC; retinal vessel density (VD), quantified from FA; ocular BF, assessed using optic nerve head (ONH) vessel-area mean blur rate (ONH-MV); and retinal and optic nerve gene expression, evaluated by quantitative PCR. After ONC, VD significantly decreased on days 4 through 28 ( P < 0.001). Retinal VD reduction coincided with increased retinal expression of inflammatory mediators ( Il6 and Tnf ), glial activation markers ( Edn2 , Tspo , and Gfap ), and the necroptosis-related gene Ripk3 on day 4 ( P < 0.05). ONH-MV showed a nonsignificant reduction on day 4 ( P > 0.05), reaching significance on days 7 through 28 ( P < 0.01). ONH-MV reduction coincided with increased expression of genes associated with glial activation and A1 astrocyte-related responses ( Tnf , Tspo , C1qa , Gbp2 , and Serping1 ; P < 0.05) on day 28. This suggests that reduced retinal VD and reduced ONH BF after neuronal injury coincide with inflammatory and glial responses in the retina and glial activation in the optic nerve.