Detection of gonioscopically occludable angles and primary angle closure glaucoma by estimation of limbal chamber depth in Asians: modified grading scheme. Foster PJ, Devereux JG, Alsbirk PH, Pak Lee PS, Uranchimeg D, Machin D, Johnson GJ,*(1) Baasanhu J. Br J Ophthalmol 2000;84:186-192.