Visualization of anterior chamber angle dynamics using optical coherence tomography

Abstract

Purpose: To describe the technology of optical coherence tomography (OCT) in imaging the anterior chamber angles and its impact on understanding the pathophysiology of angle-closure glaucoma (ACG).

Design: Observational case series.

Participants: Three subjects with, respectively, impending angle-closure attack, plateau iris syndrome, and phacomorphic glaucoma were recruited.

Methods: The anterior chamber angle in each patient was imaged with a commercially available OCT unit. The angle configurations were assessed and compared before and after laser peripheral iridotomy (LPI) and argon laser peripheral iridoplasty (ALPI).

Main outcome measures: Visualization of the changes in the anterior chamber angle configurations and normalization of the intraocular pressure (IOP).

Results: A patient with impending angle-closure attack precipitated by a topical mydriatic agent was treated with LPI. Optical coherence tomography imaging of the anterior chamber angles was performed before and after the laser procedure. Conversion of anterior iris bowing and angle crowding to iris straightening and angle opening after LPI was demonstrated. Intraocular pressure became normalized with the change in angle configuration. The second patient presented with symptoms of intermittent angle-closure attacks and was initially diagnosed with primary ACG. Despite successful LPI, the angles remained occludable, and the IOP continued to be elevated. Optical coherence tomography was used to review the anterior chamber angle configuration and demonstrated a typical pattern compatible with the diagnosis of plateau iris syndrome. Subsequent ALPI converted the plateau configuration to open angle, with normalization of IOP and disappearance of symptoms. The third patient presented with an acute angle-closure attack and was diagnosed with phacomorphic glaucoma. Argon laser peripheral iridoplasty was performed successfully to open the angle, as evident by the OCT images, and the IOP was brought under control, together with relief of symptoms.

Conclusions: The commercially available OCT unit can be practically employed for anterior chamber angle imaging. The different patterns of angle configurations are correlated with the underlying pathophysiology in different forms of ACG.