Dark-room prone-position test for intermittent angle closure

To determine the efficacy and safety of the dark-room prone-position test (DRPT) for intermittent angle closure (IAC) and to investigate the correlation between A-scan ultrasound biometric measurements and the results of DRPT.

Medical records were reviewed of 37 eyes in 24 patients who were diagnosed with IAC and received DRPT. The increase of intraocular pressure (IOP) induced by DRPT and the results from A-scan ultrasound biometric measurements were obtained. An increase in IOP of at least 8 mmHg from baseline was considered a positive result for DRPT. Associations between the increase of IOP induced by DRPT and the parameters of A-scan biometry were tested by linear regression analysis.

The DRPT results were positive in 28 eyes of 19 patients. After DRPT, the IOP returned to near-baseline levels within 2 hours in all patients; some patients were treated with anti-glaucoma eye drops. Lens thickness was significantly correlated with the amount of IOP elevation induced by DRPT (r=0.338, p=0.041).

DRPT is a safe and effective test in patients with IAC. DRPT can be used effectively to make a concrete diagnosis of IAC. Lens thickness appears to be associated with a positive response to DRPT.