Swept-source optical coherence tomography assessment of Schlemm's canal after phacoemulsification with goniosynechialysis in Chinese patients with primary angle-closure glaucoma.

BACKGROUND

Primary angle-closure glaucoma (PACG) is a leading cause of irreversible blindness worldwide. However, the features of the morphology of Schlemm's canal (SC) in PACG eyes after phacoemulsification with goniosynechialysis (phaco-GSL) surgery are still unknown. This study aimed to evaluate changes in the SC in Chinese patients with PACG after phaco-GSL using swept-source optical coherence tomography (SS-OCT).

METHODS

In this prospective, cross-sectional study, 70 patients with PACG [of whom 35 had acute primary angle-closure glaucoma (APACG) and 35 had chronic primary angle-closure glaucoma (CPACG)] who were scheduled to undergo phaco-GSL surgery were recruited from the Eye, Ear, Nose, and Throat Hospital of Fudan University from December 2021 to December 2022. The anterior chamber angle (ACA), Schlemm's canal diameter (SCD), and Schlemm's canal area (SCA) were measured by SS-OCT at the baseline, and 1 month, 3 months and 6 months after surgery. A multivariate linear regression analysis was conducted to examine the predictors of change in the mean SCA and SCD.

RESULTS

Postoperative intraocular pressures (IOPs) were significantly reduced in both the APACG and CPACG patients (both P<0.01). The ACA, SCD, and SCA increased significantly after surgery, and this increase was maintained to the end of the follow-up period in both the APACG group (SCD: 104.62±8.70 176.54±16.97 μm; SCA: 2,904.89±706.88 5,315.58±1,078.29 μm; all P<0.01) and CPACG group (SCD: 105.89±16.71 168.78±17.64 μm; SCA: 2,775.99±559.28 5,055.54±803.38 μm; all P<0.01). However, there was no significant difference in the increase between the APACG and CPACG groups (P>0.05). The multiple linear regression analysis showed that the IOP change was associated with the SCD change (β =0.281, P=0.040) and SCA change (β =0.295, P=0.039).

CONCLUSIONS

SC expansion was observed after phaco-GSL surgery in patients with PACG (both APACG and CPACG). A correlation between SC expansion and the IOP decrease was also observed. Our findings suggest that SC provides valuable information that could be used to assess the efficacy of phaco-GSL.