Lamina Cribrosa Microstructure in Nonhuman Primates With Naturally Occurring Peripapillary Retinal Nerve Fiber Layer...

Area of Science:

• Ophthalmology and Vision Science
• Neuroscience
• Biomedical Engineering

Background:

• The lamina cribrosa (LC) is a critical optic nerve head structure implicated in the initial axonal damage observed in glaucoma.
• Circumpapillary retinal nerve fiber layer thickness (RNFL-T) is a standard clinical metric for quantifying glaucomatous damage.

Purpose of the Study:

• To investigate in vivo, three-dimensional (3D) microstructural differences of the lamina cribrosa (LC) in nonhuman primates (NHPs) with naturally occurring glaucoma.

Main Methods:

• Spectral-domain optical coherence tomography (OCT) was used to acquire optic nerve head scans from rhesus monkeys.
• Eyes were categorized into a study group (thinnest RNFL-T) and a control group (average RNFL-T).
• Automated segmentation algorithms analyzed LC microstructure, including beam thickness, pore diameter, beam-to-pore ratio (BPR), and connective tissue volume fraction (CTVF).

Main Results:

• NHPs with thinner RNFL-T exhibited significantly smaller global and sectoral pore diameters and a larger BPR compared to controls.
• Global RNFL-T positively correlated with global pore diameter across all eyes.
• BPR and connective tissue volume fraction (CTVF) were significantly and negatively associated with superior quadrant RNFL-T.

Conclusions:

• Significant global and sectoral microstructural differences in the lamina cribrosa (LC) were observed between eyes with thin and normal RNFL-T.
• These findings suggest structural alterations in the LC are associated with naturally thinning RNFL in NHPs, a characteristic of glaucomatous damage.
• Further research is needed to determine if these LC differences are a cause or a consequence of RNFL damage.