SCIENTIFIC CORRESPONDENCE

Screening for primary angle closure in Mongolia: a randomised controlled trial to determine whether screening and prophylactic treatment will reduce the incidence of primary angle closure glaucoma in an east Asian population

W P Nolan¹, J Baasanhu², A Undraa², D Uranchimeg², S Ganzorig² and G J Johnson¹

¹ Department of Epidemiology and International Eye Health, Institute of Ophthalmology, London, UK
² Department of Ophthalmology, Medical University Central Hospital, Ulaanbaatar, Mongolia

Correspondence to:
Correspondence to:
Winifred Nolan, Department of Epidemiology and International Eye Health, Institute of Ophthalmology, 11–43 Bath Street, London EC1V 9EL, UK;
winnienolan{at}hotmail.com

Aim: To describe the methods used and initial results of a prospective study designed to determine whether screening and prophylactic treatment will reduce the incidence of primary angle closure glaucoma (PACG) in Mongolia.

Methods: A total of 4725 individuals aged 50 years and above were recruited to the study and randomised to intervention or control groups. All subjects had non-mydriatic optic disc examination. The intervention arm had measurement of anterior chamber depth (ACD) by A-scan ultrasound and intraocular pressure (IOP) with Tonopen. Gonioscopy was performed on test positive cases (ACD <2.53 mm or IOP 24 mm Hg either eye). Those with occludable angles were offered laser iridotomy. Primary outcome will be incidence of PACG at 5 year follow up.

Results: Glaucoma was diagnosed in 128 (2.7%) subjects. Of the remaining 4597, 2293 were randomised to intervention. Intervention as allocated was received by 2280 (99.4%) individuals. 160 (23.4%) of 685 test positive cases had occludable angles, of which 156 were treated with iridotomy.

Conclusions: This trial is a further step in determining whether screening and prophylactic treatment for primary angle closure in east Asian populations will reduce the incidence of glaucoma.

Keywords: screening; primary angle closure glaucoma

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