Optic nerve head changes after short-term intraocular pressure elevation in acute primary angle-closure suspects

Area of Science:

• Ophthalmology
• Optometry
• Glaucoma Research

Background:

• Intraocular pressure (IOP) elevation is a key risk factor for optic nerve damage.
• The dark room prone provocative test (DRPPT) is used to assess acute primary angle-closure (APAC) suspects.
• Understanding optic nerve head (ONH) morphology changes during IOP fluctuations is crucial for diagnosing and managing glaucoma.

Purpose of the Study:

• To investigate the morphological changes in the optic nerve head after acute IOP elevation induced by the DRPPT.
• To correlate IOP changes with specific ONH topographic parameters.

Main Methods:

• Prospective cohort study involving APAC suspects undergoing DRPPT.
• Baseline and post-DRPPT measurements of IOP and ONH topography using spectral-domain optical coherence tomography (SD OCT).
• Analysis of 3-dimensional ONH parameters, including optic cup dimensions, lamina cribrosa (LC) thickness, and neuroretinal rim width.

Main Results:

• A significant IOP elevation occurred in participants during DRPPT.
• Eyes with IOP increase >15 mmHg showed increased optic cup width and depth.
• These eyes also exhibited decreased lamina cribrosa thickness and neuroretinal rim width (temporal and nasal).
• Bruch's membrane opening (BMO) diameter and anterior LC surface position remained unchanged.

Conclusions:

• A substantial IOP increase (>15 mmHg) during DRPPT induces significant ONH remodeling in APAC suspects.
• Observed changes include optic cup enlargement, neuroretinal rim thinning, and LC thinning.
• The optic disc size and anterior LC surface position are stable, suggesting tissue condensation rather than structural expansion.