Abstract
Purpose: :
To study for the first time the population distribution and longitudinal aging changes of anterior chamber angle width (angle-opening distance at 500 um [AOD500], angle recess area [ARA]), and its biometric determinants, among Chinese adults.
Methods: :
A population-based sample of persons aged 35 years and above residing in Guangzhou, China, who had not undergone refractive, incisional or laser eye surgery, underwent automated keratometry, anterior segment ocular coherence tomography (AS-OCT), and laser inteference biometry in December 2008 and December 2010.
Results: :
Testing was carried out in both 2008 and 2010 on 736 subjects (mean age 51.9 +/- 11.2 years, 53.9% female), among whom, 527 (71.6%) had complete data. (The principal reason for missing data, the rate of which is comparable to previous reports, was difficulty in identifying the scleral spur on AS-OCT.) Mean AOD500 (2008: 0.25 ± 0.14; 2010: 0.21 ± 0.13, P < 0.001) and mean ARA (2008: 21.7 +/- 5.26; 2010: 21.06 +/- 3.61, P < 0.001) declined significantly for all subjects. The decline was most pronounced among younger persons (AOD500: P < 0.003; ARA: P < 0.001, chi-square test for trend), and those with baseline AOD500 in the narrower quartiles (ARA and AOD500 both P < 0.001 test for trend). AOD500 actually increased among those with the widest angles at baseline (P < 0.001).
Conclusions: :
The narrowest angles at baseline show the most rapid narrowing, while the widest angles at baseline may actually grow wider. These pronounced differences in rate of angle narrowing over time between individuals are important in explaining variation in risk for angle closure. The observed more rapid decline in angle width among younger persons is consistent with the prevalence of angle closure, which increases in the 40s and 50s and peaks in the 60s.
Keywords: clinical (human) or epidemiologic studies: biostatistics/epidemiology methodology • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • anterior chamber