AS-OCT may help evaluate primary angle closure mechanisms and treatment

This study demonstrated that quantitative anterior chamber (AC) parameters measured using anterior segment optical coherence tomography (AS-OCT) show differences in primary angle closure (PAC) mechanisms. The authors found that quantitative AC parameters, together with qualitative information from the AS-OCT images, are useful in determining the mechanism(s) of PAC, and this in turn could assist clinicians in treating the underlying mechanism(s) effectively.

Using AS-OCT, they studied the degree of difference among the four PAC mechanisms in 48 consecutive patients with PAC glaucoma or PAC seen at a hospital in Singapore. The patients underwent complete ophthalmic examination and AS-OCT imaging of nasal-temporal angles.

Images were categorized into the four PAC mechanisms: pupil block, plateau iris configuration, thick peripheral iris roll and exaggerated lens vault. The authors computed parameters for AC depth central, AC depth at 1000 µm and 2000 µm anterior to scleral spur, lens vault, AC area, angle opening distance, trabecular iris space area and iris thickness.

The mean values of AC depths were significantly different among the four groups (central, at 2000 µm, 1000 µm, lens vault, AC area; P < 0.001 for all). Multivariate analysis showed AC depth central, and AC depth at 2000 µm and AC area were higher in plateau iris and thick peripheral iris roll and lower in exaggerated lens vault (P < 0.001) compared with pupil block mechanism. Lens vault was greater in exaggerated lens vault (P < 0.001) and lesser in plateau iris and thick peripheral iris roll compared with pupil block mechanism.