Anatomical effects of clear lens extraction by phacoemulsification versus trabeculectomy on anterior chamber drainage angle in primary angle-closure glaucoma (PACG) patients

Abstract

Purpose: To document the anatomical effects of clear lens extraction by phacoemulsification versus trabeculectomy on anterior chamber angle in patients with primary angle-closure glaucoma (PACG).

Methods: Gonioscopy and ultrasound biomicroscopy (UBM) were performed pre-operatively, and at 1 year after clear lens extraction or trabeculectomy in PACG eyes.

Results: Fifty PACG eyes of 50 patients were included. Twenty-six eyes had clear lens extraction by phacoemulsification, while 24 eyes underwent trabeculectomy. The mean extent of synechial angle closure was significantly reduced from 272.3° ± 57.3° to 253.3° ± 70.5° (p = 0.007) by phacoemulsification, but it was only reduced from 285.0° ± 64.6° to 283.1° ± 55.5° (p = 0.32) by trabeculectomy. The mean angle-opening distance at 500 microns from sclera spur (AOD500) measured by UBM was significantly increased from 220.3 ± 93.8 microns to 388.9 ± 134.1 microns (p < 0.001) by clear lens extraction, but decreased from 220.9 ± 79.8 microns to 214.5 ± 70.2 microns (p = 0.11) by trabeculectomy. The mean anterior chamber depth (ACD) measured by UBM was significantly increased from 1,983.8 ± 176.8 microns to 3335.0 ± 174.2 microns (p < 0.001) by clear lens extraction, but decreased from 2,000.2 ± 214.5 microns to 1975.8 ± 218.2 microns (p = 0.001) by trabeculectomy.

Conclusion: Compared to trabeculectomy, clear lens extraction resulted in a significant reduction in synechial angle closure, and an increase in anterior chamber angle width and anterior chamber depth in PACG eyes without cataract.