The utility of symptoms in identification of primary angle-closure in a high-risk population.

OBJECTIVE: To examine the frequency of symptoms associated with primary angle closure in an East Asian population with high rates of disease. DESIGN: Population-based survey. PARTICIPANTS: One thousand adults from rural and urban provinces of Mongolia were examined. METHODS: A standard questionnaire was used to determine a history of symptoms of angle closure. All participants underwent applanation tonometry, gonioscopy, and slit-lamp examination by the same observer. The frequency of symptoms was compared between normal subjects and those in 3 high-risk or affected groups: gonioscopically confirmed occludable angles, peripheral anterior synechiae (PAS) detected on gonioscopy, and anterior chamber depth of less than 2.5 mm. MAIN OUTCOME MEASURES: The frequency of symptoms associated with primary angle closure. RESULTS: Symptoms of visual disturbance and ocular pain traditionally linked with angle closure were reported frequently by both normal and potentially affected people. Intermittent blurring of vision at night was the only common symptom of angle closure that was significantly more frequent in people with narrow angles and PAS (P = 0.004, 48.4% vs. 31.0% narrow angles; P = 0.001, 54.3% vs. 30.6% PAS), but not in those with shallow anterior chambers (P = 0.670, 38.3% vs. 30.9%). CONCLUSIONS: Direct questioning about symptoms associated with angle closure identified high rates of positive responses in both affected and unaffected groups. Although the rate of symptoms tended to be higher in affected people, none of these symptoms were specific enough to be considered useful as a diagnostic criterion.

Anterior chamber depth and the risk of primary angle closure in 2 East Asian populations.

OBJECTIVE: To evaluate the risk of peripheral anterior synechiae (PAS) and glaucomatous optic neuropathy attributable to primary angle closure at varying anterior chamber depths (ACDs) in two East Asian populations. METHODS: Participants 40 years and older were from 2 population-based glaucoma surveys in Mongolia and Singapore. Central ACD was measured by optical pachymetry. Presence of PAS was determined by dynamic gonioscopy. Cases with secondary PAS were excluded. Glaucomatous optic neuropathy was diagnosed in subjects with structural and functional evidence of glaucoma. RESULTS: A total of 2032 subjects, consisting of 942 Mongolians and 1090 Chinese Singaporeans, were included in this study. A logistic model of the relationship between ACD and PAS among Singaporeans showed a consistent, incremental increase in PAS across the entire range of ACD. In deeper anterior chambers the rate of PAS exceeded that seen in Mongolians. In Mongolians, there was a clear threshold for ACD (2.4 mm) at or above which PAS were very uncommon. With ACD less than 2.4 mm, the rate of PAS rose rapidly to overtake that seen in Singaporeans. CONCLUSIONS: Shallow anterior chambers are a significant risk factor for angle closure in East Asians, although the nature of the association is specific to the individual population. There was a trend toward higher rates of glaucomatous optic neuropathy in people with the shallowest anterior chambers.

Ocular biometry and refraction in Mongolian adults.

OBJECTIVE: To describe the variation in ocular biometry and its association with refraction in adult Mongolians. METHODS: The study included 1800 subjects, aged 40 years or more, who were selected in two Mongolian provinces-Hövsgöl and Omnögobi-to participate in this population survey. Axial length (AL) and its components, as well as noncycloplegic autorefraction and corneal power (CP), were measured. RESULTS: Of those selected, 1617 subjects (90.0%) were examined. Mean +/- SD of AL was 23.13 +/- 1.15 mm. There was a very small but significant increase in mean AL with age (0.05 mm per decade, P = 0.03). Autorefraction was performed on 620 of 675 subjects of those examined in Omnögobi. The age and gender standardized prevalences of myopia (< -0.5 D), emmetropia, hyperopia (> +0.5 D), astigmatism (< -0.5 D of cylinder) and anisometropia (>1.0 D difference between eyes) were 17.2%, 49.9%, 32.9%, 40.9%, and 10.7%, respectively. Prevalence of myopia showed no clear trend with increasing age, whereas hyperopia, astigmatism, and anisometropia all increased monotonically. Multiple regression models revealed that AL (P < 0.001) and VCD (P < 0.001) were the strongest determinants of refractive error. CONCLUSIONS: In this cross-sectional study of adult Mongolians, a much lower prevalence of myopia was found than in other East Asian populations studied to date. The mean AL differed little between age groups, in marked contrast to data on Chinese people.