Citation

In rats and mice, limbar tissues of the left eye were laser-photocoagulated (LP) and ocular hypertension (OHT) effects were investigated 1 week to 6 months later. To investigate the innermost layers, retinas were examined in wholemounts using tracing from the superior colliculi to identify retinal ganglion cells (RGCs) with intact retrograde ax- onal transport, melanopsin immunodetection to identify intrinsically photosensitive RGCs (m + RGC), Brn3a immunodetection to identify most RGCs but not m + RGCs, RECA1 immu- nodetection to examine the inner retinal vessels, and DAPI staining to detect all nuclei in the GC layer. The outer retinal layers (ORLs) were examined in cross sections analyzed morpho- metrically or in wholemounts to study S- and L-cones. Innervation of the superior colliculi was examined 10 days to 14 weeks after LP with orthogradely transported cholera toxin subunit B. By 2 weeks, OHT resulted in pie-shaped sectors devoid of FG + RGCs or Brn3a + RGCs but with large numbers of DAPI + nuclei. Brn3a + RGCs were significantly greater than FG + RGCs, indicating the survival of large numbers of RGCs with their axonal transport impaired. The inner retinal vasculature showed no abnormalities that could account for the sectorial loss of RGCs. m + RGCs decreased to approximately 5051% in a diffuse loss across the retina. Cross sections showed focal areas of degeneration in the ORLs. RGC loss at 1 m diminished to 2025% and did not progress further with time, whereas the S- and L-cone populations di- minished progressively up to 6 m. The retinotectal projection was reduced by 10 days and did not progress further. LP-induced OHT results in retrograde degeneration of RGCs and m + RGCs, severe damage to the ORL, and loss of retinotectal terminals.