Use of limbal and central anterior chamber depth measurements in detecting eyes with gonioscopically occludable angles and primary angle closure glaucoma in Ibadan.

The routine use of gonioscopy for the evaluation of drainage angles in developing countries is not always done because of the busy clinics. The purpose of this study was to evaluate the performance of 2 tests: Peripheral Anterior Chamber Depth (PACD) measurement and Central Anterior Chamber Depth (CACD) measurement in detecting occludable angles and primary angle closure within subjects with primary glaucoma and control subjects. Two hundred and forty subjects with primary glaucoma and a control group of 250 subjects were studied. PACD was measured with the Van Herrick's method while CACD was measured by the technique described by Lowe. The findings were compared to the gonioscopic appearance of the drainage angles in the two groups. PACD gradings 0 to 2 correctly identified 28 out of 36 eyes (77.8%) of subjects with PACG who had gonioscopically closed angles. The test identified correctly 168 out of 204 eyes (82.4%) with gonioscopically open angles among subjects with primary glaucoma. Among subjects with no glaucoma, PACD gradings 0 to 2 correctly identified 12 out of the 14 eyes with gonioscopically occludable angles, while the test identified 238 eyes without occludable angles, gonioscopy identified 236 out of 250 of such eyes. A CACD less than 2.5 mm was present in only 21 eyes of 36 eyes with occludable angles by gonioscopy among those with PACG. In the other 15 eyes with occludable angles, CACD was more than 2.5 mm. PACD performed well in detecting occluded angles in this study, CACD was useful but less so than PACD in established cases of PACG. Subjects with PACG but whose CACD was 2.5 mm or more may have plateau iris. PACD and CACD are both useful methods in identifying occludable angles in eyes of Nigerian subjects studied.