Dynamic analysis of iris configuration with anterior segment optical coherence tomography

Area of Science:

• Ophthalmology
• Biomedical Optics
• Anatomy

Background:

• Anterior chamber angle width is crucial for intraocular pressure regulation.
• Iris configuration dynamically changes with light conditions.
• Primary angle closure is a significant risk factor for glaucoma.

Purpose of the Study:

• To evaluate dynamic changes in iris configuration using anterior segment optical coherence tomography (ASOCT).
• To assess the association between iris bowing and anterior chamber angle width.

Main Methods:

• Analyzed 46 normal subjects with open angles and 40 with narrow angles.
• Captured dynamic iris bowing changes with ASOCT video recording under dark-light conditions.
• Measured iris bowing, anterior chamber angle, and pupil diameter; analyzed associations with regression models.

Main Results:

• Identified three dynamic iris bowing patterns: convex-to-convex, concave-to-convex, and concave-to-concave.
• Narrow angles were predominantly convex-to-convex; older age and shorter axial length were associated with this pattern.
• Iris bowing and anterior chamber depth (ACD) were independently associated with anterior chamber angle width.

Conclusions:

• Iris bowing is a critical biometric parameter influencing anterior chamber angle width, independent of ACD.
• Investigating iris dynamics provides a novel perspective on primary angle closure mechanisms and risk.