Mean Angle Width Predictive of Angle Closure in Suspects

Baseline mean angle width is an independent predictive risk factor for progression of angle closure in a cohort of adults from rural China, according to research results published in Glaucoma. 

Researchers sought to investigate the progression of primary angle closure suspect (PACS) and the associated risk factors based on a population of adults from rural China who participated in the Handan Eye Study. 

The Handan Eye Study was a population-based cohort study; baseline research was conducted from 2006 to 2007 and included 6830 adults from 13 villages in Yongnian County. Follow-up research was conducted between 2012 and 2013 and included 5394 adults (85.3% of survivors) who returned to undergo a repeat evaluation. 

Similar procedures for questionnaires and examinations were used for the baseline and follow-up studies. Researchers measured presenting visual acuity, best corrected visual acuity (BCVA), objective and subjective refraction, slit-lamp biomicroscopy, visual field examination, IOP measurement, gonioscopy, A-scan ultrasound biometry, and fundus examination. 

In total, 2046 participants underwent gonioscopic examination in the baseline study; 1102 of these participants underwent the follow-up examination. A total of 543 participants with PACS were included in the study. 

PACS participants who underwent both baseline and follow-up gonioscopy were younger, had shallower central anterior chamber depth, thicker lens, and shorter axial length with statistically significant differences. There were no differences in gender, body mass index, spherical equivalence, corneal curvature radios, intraocular pressure (IOP), or mean angle width between the groups. 

Of the participants diagnosed with PACS, 402 were bilateral and 132 were unilateral (73 in the right eye and 59 in the left eye). After exclusion, data from 526 eyes of 526 participants with PACS at baseline were available for analysis (415 women). 

Progression from PACS to primary angle closure/primary angle-closure glaucoma (PAC/PACG) was seen in 32 patients. Twenty-seven adults with bilateral PACS progressed to PAC (11 bilateral). One adult with bilateral PACS progressed to right eye PACG and the presence of PAS with an IOP higher than 21 mmHg. Four cases with unilateral PACS progressed to PAC (2 right eye and 2 left eye). A total of 494 PACS cases did not show progression after the 5-year follow-up period. 

Compared with those who did not progress to PAC/PACG, cases with progression had shallow LACD and central ACD and narrower mean angle width with statistically significant differences. 

Results of a univariate logistic regression model showed that baseline LACD< mean angle width, and central ACD were significant predictors associated with the progression of PACS. Multivariate logistic regression analysis results showed that narrower mean angle was a significant risk factor for PAC/PACG progression from baseline PACS. 

Study limitations include loss to follow-up goniscopic examination, and the use of different observers to perform baseline and follow-up examinations. 

“Baseline narrower mean angle width was found to be [a] predictive factor for the progression of PAC/PACG in PACS eyes,” the research says. 

Reference

Zhang Y, Thomas R, Zhang Q, Li SZ, Wang NL. Progression of primary angle closure suspect to primary angle closure and associated risk factors: the Handan eye study. Invest Ophthalmol Vis Sci. 2021;62(7):2. doi:10.1167/ivos.62.7.2