Microstructural Deformations Within the Depth of the Lamina Cribrosa in Response to Acute In Vivo Intraocular...

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Neuroscience

Background:

• The lamina cribrosa (LC) is a critical site for initial glaucomatous damage.
• Understanding microstructural changes in the LC under varying intraocular pressure (IOP) is vital for glaucoma research.

Purpose of the Study:

• To investigate in vivo microstructural deformation within the LC volume.
• To analyze deformation in response to acute IOP modulation while maintaining fixed intracranial pressure (ICP).

Main Methods:

• In vivo spectral-domain optical coherence tomography (OCT) was used on rhesus macaque optic nerve heads (ONH).
• IOP was modulated across baseline, H1-IOP (30 mm Hg), and H2-IOP (40-50 mm Hg) while ICP was fixed.
• 3D scan registration allowed for microstructure measurements within the LC volume.

Main Results:

• Only 50% of eyes showed LC beam-to-pore ratio (BPR) and microstructure deformations.
• Eyes with BPR deformation had higher baseline connective tissue volume fraction (CTVF) and lower pore aspect ratio.
• LC deformation magnitude varied significantly between the anterior surface and deeper regions.

Conclusions:

• The LC deforms unevenly throughout its depth in response to IOP changes at fixed ICP.
• Analyzing only the anterior LC surface is insufficient to capture full microstructural deformation.
• Higher CTVF in LC deformer eyes suggests a role in susceptibility to IOP-induced changes.