Smith-method assessment of anterior chamber depth for screening for narrow anterior chamber angles

PURPOSE: To compare the axial anterior chamber depth (ACD) using the Smith method, in patients under treatment for primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG), with an age-matched control group. MATERIALS AND METHODS: Triplicate just-touching-slit-length (JTSL) measurements of the axial anterior chamber depth were determined in 198 eyes of 99 patients (39 control; 36 POAG; and 24 PACG) recruited from King Saud University clinics, Riyadh, Saudi Arabia. Goldmann tonometry and gonioscopy were carried out as a part of the patient's routine examination. Subjects with a history of intraocular surgery for glaucoma or any other anterior segment disease were excluded form the study. The average ACD estimate by the JTSL method were compared among the various groups. RESULTS: The average JTSL estimates were: Control group 2.33+/-0.68 mm (axial ACD estimate = JTSL estimate x 1.4); POAG group 1.98+/-0.97 mm; PACG group 0.65+/-0.41 mm. There was no significant reduction (P = 0.068) of the JTSL estimate in the POAG group, compared to the control group. There was a statistically significant (P < 0.001) reduction of the JTSL estimate in the PACG group, compared to both the control and POAG groups. CONCLUSION: The Smith-method JTSL technique may be used for non-invasive rapid screening, to help identify patients at risk of developing angle-closure, during routine examination of patients in the ophthalmology clinic.