Optic disc swelling in acute primary angle closure: Associated factors and longitudinal OCT changes

To identify clinical factors associated with optic disc swelling (ODS) in acute primary angle-closure glaucoma (AACG) and to evaluate longitudinal structural changes in the retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) using optical coherence tomography (OCT).

A retrospective study was conducted on 102 consecutive eyes from AACG patients who underwent laser iridotomy (LI) and had at least two years of follow-up. Patients were classified into ODS and control groups based on optic disc appearance and OCT findings. Associated factors were analyzed using multivariate logistic regression. RNFL and GCIPL thicknesses were measured at six time points post-LI. Thinning rates were calculated for short-term (1 week-6 months) and long-term (6 months-2 years) periods and compared between groups.

ODS was identified in 42 eyes. Larger pupil diameter (odds ratio = 15.23) and longer symptom duration (odds ratio = 2.03) were independently associated with ODS. Mean IOP was consistently < 16 mmHg in both groups at any time point, yet ODS eyes showed RNFL thickening followed by sustained thinning, whereas GCIPL thickness declined continuously. From 6 months to 2 years, RNFL thinning averaged - 2.86 μm/year in ODS vs. -0.77 μm/year in controls (P = 0.005); GCIPL thinning was - 1.27 vs. -0.69 μm/year (P = 0.006). Fellow eyes showed no differences in RNFL or GCIPL thinning rates between groups (P = 0.123 and 0.080).

ODS in AACG is linked to delayed treatment and larger pupil size, suggesting more severe ischemic stress. ODS eyes exhibit sustained structural loss despite IOP control, highlighting the need for early intervention and tailored follow-up strategies.