To assess long-term changes in the anterior segment (AS) of eyes with different angle-closure mechanisms.

Retrospective cohort study.

In total, 133 eyes (from 75 participants) with angle closure were enrolled. All eyes received laser iridotomy (LI) during the follow-up period. Serial anterior segment optical coherence tomography (AS-OCT) imaging was performed during a mean follow-up of 4 years. Participants were categorized into 4 groups according to angle-closure mechanisms, based on baseline AS-OCT images: pupillary block (PB), plateau iris configuration (PIC), thick peripheral iris roll (TPIR), and exaggerated lens vault (ELV). Linear mixed-effect models were applied to evaluate the longitudinal changes in AS-OCT parameters (anterior chamber depth [ACD], lens vault [LV], and angle opening distance [AOD]).

Forty-six eyes (35%) were classified as PB, 30 (23%) as PIC, 34 (26%) as TPIR, and 23 (17%) as ELV. The follow-up period was 41-54 months. At baseline, ACD was shallowest in ELV, followed by PB, TPIR, and PIC, in order. The PIC group showed significantly wider AOD than the other groups at baseline. ACD decreased and LV increased over time in all groups, especially in the PIC group. After LI, the angle widened in the PB and TPIR groups, but not in the PIC and ELV groups.

AS parameters changed differently in the 4 groups. The effects of LI on AOD also differed among groups. Identification of the angle-closure mechanism may help predict progressive changes in AS parameters in eyes with angle closure.