Retinal neurodegeneration in experimental glaucoma.

Area of Science:

• Ophthalmology
• Neuroscience
• Cell Biology

Background:

• Ocular hypertension (OHT) is a major risk factor for glaucoma.
• Understanding the cellular and structural changes in the retina following OHT is crucial for developing effective treatments.

Purpose of the Study:

• To investigate the long-term effects of laser-induced ocular hypertension (LP-induced OHT) on retinal ganglion cells (RGCs), intrinsically photosensitive RGCs (m(+)RGCs), outer retinal layers (ORLs), and the retinotectal projection in rats and mice.

Main Methods:

• Laser-photocoagulation (LP) was used to induce OHT in rats and mice.
• Retinal tissues were examined using wholemounts and cross-sections.
• Techniques included tracing for RGCs, immunodetection for m(+)RGCs and Brn3a(+)RGCs, RECA1 staining for vasculature, and DAPI staining for nuclei.
• Morphometric analysis of ORLs and examination of retinotectal projections were performed.

Main Results:

• LP-induced OHT caused sectorial loss of RGCs with impaired axonal transport and a diffuse loss of m(+)RGCs.
• No vascular abnormalities were found to explain RGC loss.
• Focal degeneration occurred in the ORLs, and S- and L-cone populations diminished progressively.
• Retinotectal projection was reduced and stabilized.

Conclusions:

• LP-induced OHT leads to retrograde degeneration of RGCs and m(+)RGCs.
• Severe damage to ORLs and loss of retinotectal terminals are significant consequences.
• The findings highlight the complex and progressive nature of retinal damage following OHT.