Quantitative Microstructural Analysis of Cellular and Tissue Remodeling in Human Glaucoma Optic Nerve Head

Area of Science:

• Ophthalmology
• Neuroscience
• Cell Biology

Background:

• The lamina cribrosa (LC) is a crucial sieve-like structure at the optic nerve head.
• Glaucoma is characterized by progressive optic nerve damage, leading to vision loss.
• Understanding structural changes in the LC is vital for glaucoma research.

Purpose of the Study:

• To quantitatively measure structural changes in lamina cribrosa (LC) cells and connective tissue in human glaucoma eyes.
• To correlate these structural alterations with the severity of glaucoma damage.

Main Methods:

• Postmortem eyes from glaucoma patients and age-matched controls were analyzed.
• Confocal and multiphoton microscopy quantified glial fibrillary acidic protein (GFAP), F-actin, and nuclear structures within the LC.
• Second harmonic generation imaging assessed LC beams, complemented by electron microscopy for collagen IV and SOX9 labeling.

Main Results:

• Glaucoma eyes showed reduced GFAP and F-actin processes and rounder nuclei within LC pores compared to controls.
• Increased F-actin process width, decreased LC beam width, and higher nuclear density correlated with greater glaucoma damage.
• Astrocytes (SOX9-positive) constituted the majority of increased cell counts in LC pores.

Conclusions:

• Glaucoma induces significant structural remodeling of the lamina cribrosa.
• These changes include astrocyte migration into axonal bundles and alterations in astrocyte morphology.
• Basement membrane production and thinning of connective tissue beams are key features of glaucoma-related LC changes.