Aim-To evaluate the performance of limbal chamber depth estimation as a means of detecting occludable drainage angles and primary angle closure, with or without glaucoma, in an east Asian population, and determine whether an augmented grading scheme would enhance test performance. Method-A two phase, cross sectional, community based study was conducted on rural and urban areas of Hövsgöl and Ömnögobi provinces, Mongolia. 1800 subjects aged 40 to 93 years were selected and 1717 (95%) of these were examined. Depth of the anterior chamber at the temporal limbus was graded as a percentage fraction of peripheral corneal thickness. An "occludable" angle was one in which the trabecular meshwork was seen in less than 90°of the angle circumference by gonioscopy. Primary angle closure (PAC) was diagnosed in subjects with an occludable angle and either raised pressure or peripheral anterior synechiae. PAC with glaucoma (PACG) was diagnosed in cases with an occludable angle combined with glaucomatous optic neuropathy and consistent visual morbidity. Results-Occludable angles were identified in 140 subjects, 28 of these had PACG. The 15% grade (equivalent to the traditional "grade 1") yielded sensitivity and specificity of 84% and 86% respectively for the detection of occludable angles. The 5% grade gave sensitivity of 91% and specificity of 93% for the detection of PACG. The interobserver agreement for this augmented grading scheme was good (weighted kappa 0.76). Conclusions-Thetraditional limbal chamber depth grading scheme oVers good performance for detecting occludable drainage angles in this population. The augmented scheme gives enhanced performance in detection of established PACG. The augmented scheme has potential for good interobserver agreement. (Br J Ophthalmol 2000;84:186-192)

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.

Aim-To assess the eYcacy of Nd:YAG laser iridotomy as initial treatment for primary angle closure in a community setting in rural Mongolia. Methods-Subjectswith occludable drainage angles in two glaucoma prevalence surveys in Mongolia (carried out in 1995 and 1997) were treated with YAG laser iridotomy at the time of diagnosis. These patients were re-examined in 1998. Patency of iridotomy, intraocular pressure (IOP), visual acuity, and gonioscopic findings were recorded. Iridotomy was classified unsuccessful in eyes where further surgical intervention was required or in which there was a loss of visual acuity to <3/60 from glaucomatous optic neuropathy. Results-164 eyes of 98 subjects were examined. Patent peripheral iridotomies were found in 98.1% (157/160) of eyes that had not undergone surgery. Median angle width increased by two ShaVer grades following iridotomy. Iridotomy alone failed in 3% eyes with narrow drainage angles and either peripheral anterior synechiae or raised IOP, but normal optic discs and visual fields. However, in eyes with established glaucomatous optic neuropathy at diagnosis iridotomy failed in 47%. None of the eyes with occludable angles that were normal in all other respects, and underwent iridotomy, developed glaucomatous optic neuropathy or symptomatic angle closure within the follow up period. Conclusions-Nd: YAG laser iridotomy is eVective in widening the drainage angle and reducing elevated IOP in east Asian people with primary angle closure. This suggests that pupil block is a significant mechanism causing closure of the angle in this population. Once glaucomatous optic neuropathy associated with synechial angle closure has occurred, iridotomy alone is less eVective at controlling IOP.

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Setting: Rural and urban locations in the Hö vsgö l and Ö mnö gobi provinces, Mongolia. Participants: Nine hundred forty-two (94.2%) of 1000 individuals in Hö vsgö l (1995) and 775 (96.9%) of 1000 individuals in Ö mnö gobi (1997) aged 40 years or older were examined. Main Outcome Measures: Anterior chamber depth was measured by optical pachymetry, slitlamp-mounted Amode ultrasound, and handheld ultrasound. Gonioscopy was used to detect occludable angles, defined as one in which the trabecular meshwork was visible for less than 90°of angle circumference. Primary open-angle glaucoma was diagnosed in subjects with an occludable angle and glaucomatous optic neuropathy with visual morbidity. The area under the curve in a receiver operating characteristic plot was used to compare test performance. Results: Optical pachymetry outperformed the slitlampmounted ultrasound method of anterior chamber depth measurement (area under the curve, 0.93 and 0.90, respectively; z test, P = .001). Handheld ultrasound (area under the curve, 0.86) was inferior to optical measurement (z test, P = .001) but did not differ significantly from slitlamp ultrasound (z test, P = .06). The optical method gave sensitivity of 85% and specificity of 84% at a screening cutoff of less than 2.22 mm for detecting occludable angles. Conclusions: Measurement of axial anterior chamber depth can detect occludable angles in this Asian population and therefore may have a role in population screening for primary angle-closure glaucoma.

Aim: To evaluate the factors associated with lack of awareness of glaucoma and late presentation to the doctor in Singapore Chinese patients with acute angle closure (AAC) Methods: A prospective, hospital based case series of 105 patients aged 35 years and above who presented with a first attack of AAC in a tertiary hospital in Singapore was conducted. A research assistant interviewed all patients face to face in clinic and recorded demographic factors, awareness of glaucoma, and subjective barriers to seeing a doctor. The time from onset of symptoms to presentation at the clinic was noted. Results: Overall, 22.9% of patients had heard of glaucoma. The multivariate adjusted odds ratio (OR) of unawareness of glaucoma in older people (> 60 years) was 1.5 (95% confidence interval (CI) 0.5 to 4.6), 3.2 (95% CI 1.1 to 9.2) for adults who were not working, and 13.8 (95% CI 1.3 to 146.7) for patients who had less than a pre-university education. A significant proportion (31.7%) of patients presented to the doctor 24 hours or more after symptoms occurred. In a multiple logistic regression model, the adjusted OR of late presentation was 8.5 (95% CI 1.04 to 69.5) if there was no car access, 5.0 (95% CI 1.0 to 24.6) if the patients spoke Chinese, and 3.3 (95% CI 0.9 to 11.9) if there was nobody to accompany to hospital. Conclusion: Glaucoma awareness among patients suffering AAC was not high. Lack of awareness was associated with increasing age, lack of formal education, and unemployment. A significant proportion of patients seek medical attention late. Risk factors for late presentation include lack of car access, nobody to accompany the patient, and speaking the Chinese language primarily. Health education programmes may help increase the knowledge and awareness of glaucoma.A growing body of data suggests that glaucoma is a leading cause of blindness in east Asia.1-3 A recent population based survey in Singapore found that glaucoma was responsible for 60% of cases of blindness. 4 Although the majority of cases diagnosed in this survey were primary open angle glaucoma (POAG), the importance of primary angle closure glaucoma (PACG) is underlined by the fact that PACG has a greater propensity to progress to blindness.3 Primary angle closure may present with symptoms (acute angle closure, AAC) or without (chronic angle closure, CAC). Symptomatic episodes occur in between 25% and 50% of people affected by angle closure.4-6 A prospective, nationwide study of incidence of AAC in Singapore recorded a rate of 12.2 per 100 000 person yearsthe highest rate yet recorded. 7 This figure was subsequently verified by study of national hospital discharge records. 8 We were alarmed that half the cases of AAC identified in our prospective incidence study waited 3 or more days before presenting to an ophthalmologist. Late presentation has previously been linked with an adverse outcome, such as poor intraocular pressure (IOP) control.9 10 Therefore, the aim of this study was to explore the health beliefs, and determine factors associated wit...

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Objective: To compare the characteristics of visual field defects in primary angle-closure glaucoma (PACG) and primary open-angle glaucoma (POAG). Methods: Subjects with primary glaucoma aged 30 years and older were prospectively considered for inclusion. Automated static white-on-white perimetry was performed. A minimum of 2 reliable tests was required with a mean deviation (MD) within 2 dB on 2 tests. Subjects with previous symptomatic angle-closure, normaltension glaucoma, visually significant cataract, or previous intraocular surgery were excluded. Results: Of 234 subjects assessed, 129 had POAG, and 105 had PACG. The MDs (POAG group, −13.3 dB; PACG group, −18.0 dB) indicated more severe visual loss in subjects with PACG. In subjects with POAG, the superior hemifield was more severely affected than the inferior. This was less pronounced in subjects with PACG. Following stratification by MD, the difference between hemifields was marked in the mild (−10 dBՅMD) and moderate (−20 dBՅMDϽ−10 dB) subgroups but was not present in the severe (MDϽ−20 dB) subgroup. We detected differences between POAG and PACG in retinal sensitivity between the superior and inferior hemifields, independent of severity of damage. Conclusions: The pattern of visual field loss was different in the 2 diseases. This may give insight into the pattern of visual loss in predominantly pressure-dependent glaucomatous optic neuropathy.