Patients with severe primary angle-closure glaucoma (PACG) may have a higher rate of plateau iris compared with individuals with early to moderate forms of the ocular condition, a new study in the American Journal of Ophthalmology reports.

A team of researchers used ultrasound biomicropscopy on 210 PACG subjects who had previously undergone laser peripheral iridotomy. The study defined plateau iris as the presence of all the following in at least two quadrants of the angle: anteriorly directed ciliary body; absent ciliary sulcus; iris angulation; flat iris plane; and iridotrabecular contact. The investigators based disease severity on the mean deviation of visual fields, and classified patients as early-to-moderate (-12dB or more), advanced (-12.01dB to -20dB) and severe (less than -20dB).

Of the 210 recruited subjects, 23 were excluded due to poor image quality. The remaining 187 were categorized as early-moderate (103), advanced (38) and severe PACG (46).

The participants were 48.1% male, and 90.9% were of Chinese ethnicity. The overall proportion of plateau iris was 36.9%, with 32% (33/103) in early-moderate, 34.2% (13/38) in advanced and 50% (23/46) in severe PACG.

Among the individuals in the severe PACG group, those with plateau iris had a significantly smaller anterior chamber area and volume compared with those without plateau iris.