Differing Associations between Optic Nerve Head Strains and Visual Field Loss in Patients with Normal- and...

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Glaucoma Research

Background:

• Glaucoma is a leading cause of irreversible blindness.
• Optic nerve head (ONH) damage is a hallmark of glaucoma.
• Understanding the biomechanical properties of the ONH is crucial for glaucoma diagnosis and treatment.

Purpose of the Study:

• To investigate the relationship between optic nerve head (ONH) strains and retinal sensitivity in patients with glaucoma.
• To determine if ONH strains under elevated intraocular pressure (IOP) are associated with visual field defects.

Main Methods:

• A cross-sectional study involving 229 patients with primary open-angle glaucoma (HTG and NTG).
• Spectral-domain optical coherence tomography (OCT) was used to image the ONH under normal and elevated IOP conditions.
• A 3D strain-mapping algorithm quantified ONH tissue strain, which was then correlated with visual field test results.

Main Results:

• Significant negative associations were found between ONH strains and retinal sensitivity in patients with high-tension glaucoma (HTG).
• Higher ONH strains corresponded to lower retinal sensitivity (1% strain increase linked to 1.1 dB decrease).
• In contrast, patients with normal-tension glaucoma (NTG) showed no significant associations, except in a specific region of the lamina cribrosa.

Conclusions:

• Elevated intraocular pressure-induced ONH strains are significantly associated with reduced retinal sensitivity in glaucoma patients.
• The findings suggest that biomechanical factors play a critical role in vision loss in HTG.
• The distinct associations between ONH strains and retinal sensitivity in HTG versus NTG may indicate different underlying disease mechanisms.