Long-term effects of mild cataract extraction versus laser peripheral iridotomy on anterior chamber morphology in primary angle-closure suspect eyes

Aim

To compare lens extraction (LE) and laser peripheral iridotomy (LPI) on anterior segment morphology in primary angle-closure suspect (PACS) eyes.

Methods

This prospective clinical trial included 144 patients with PACS who underwent either LPI or LE. Ultrasound biomicroscopy (UBM) and gonioscopy were performed before and 1 month and 2 years after operation. Main outcomes included UBM parameters and the percentage of residual angle closure.

Results

At both 1 month and 2 years of follow-up, LE showed a better effect of relieving anterior chamber crowding and widening the drainage angle, as obtaining a larger anterior chamber depth (ACD), angle opening distance, trabecular iris angle (TIA), trabecular iris space area, trabecular ciliary process distance (TCPD) and a smaller iris curvature (I-Curv) and lens vault (LV) (p<0.001). In the LPI group, angle width increased (angle opening distance at 500 µm from the scleral spur, TIA and trabecular iris space area at 500 µm from the scleral spur) and I-Curv decreased (p<0.001) at 1 month postoperatively, with no significant changes in ACD, LV or TCPD. However, at 2 years after LPI, the angle narrowed with the increase in LV over time, and the proportion of residual angle closure also increased from 21.7% to 30.4% (p<0.001). In contrast, after LE, the widened angle width, flattened iris, deepened ACD, decreased LV and increased TCPD all showed good sustainability in the comparison between 1-month and 2-year follow-up. No residual angle closure was observed either at 1 month or 2 years after LE.

Conclusions

LE was prior to LPI in widening the drainage angle. After LPI, there was a narrowing of the angle and an increase in the proportion of residual angle closure over time. LE could achieve a wider angle with no residual angle closure, and the anterior segment parameters were sustainable.

Trial registration number

ChiCTR1800016511.