Ocular hypertension in adult rodents does not affect non-RGC neurons in the ganglion cell layer but results in severe loss of cone-photorreceptors

We investigate short and long-term effects of laser photocoagulation (LP) of the limbal tissues-induced ocular hypertension (OHT) in the innermost and outer layers of the retina (OLR). Adult albino rats or mice were examined 2 weeks to 6 months after LP-induced OHT. Brn3a-immunodetection was used to identify retinal ganglion cells (RGCs) and DAPI-staining to identify all cell nuclei in the ganglion cell layer. Retinas were cut in cross sections for morphometric analysis or prepared as wholemounts to study the entire population of RGCs or L- and S-cones (immunolabeled). OHT resulted in pie-shaped retinal areas lacking Brn3a⁺RGCs but with large numbers of DAPI⁺nuclei. Cross-sections showed focal regions of degeneration affecting the ORL that became evident by 2 m and progressed up to 6 months after LP. Rat retinal wholemounts showed RGC diminished to 20–25% by 1 m with no further loss, whereas the L- or S-cones showed progressive loss up to 6 months that amounted to 19% or 33% by 1 m, to 62% or 51% by 3 m, and to 66% or 59% by 6 m, respectively. LP-induced OHT results in selective loss of RGCs within the ganglion cell layer, but there is progressive severe damage of the ORL up to 6 m.