Comparison of anterior segment optical coherence tomography and ultrasound biomicroscopy for iris parameter measurements in patients with primary angle closure glaucoma.

PURPOSE: To compare the repeatability and consistency of anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy (UBM) in measuring iris parameters in patients with primary angle closure glaucoma.

METHODS

Twenty-two patients (38 eyes) with primary angle closure glaucoma, including 5 eyes with acute angle closure glaucoma, 10 fellow eyes of acute angle closure glaucoma, and 23 eyes with chronic angle closure glaucoma, were recruited consecutively in our hospital. All subjects underwent anterior scanning by AS-OCT and UBM. Peripheral iris thickness (PIT) and iris curvature (IC) in the anterior segment image obtained by AS-OCT and UBM were measured twice. The reproducibility of these two scans was evaluated by the intraclass correlation coefficient (ICC). A paired t-test was used to compare the difference between the two scans and the 95% limits of agreement (LoA) were calculated.

RESULTS

The ICCs of PIT and IC measured by UBM were 0.892 and 0.936 respectively, while for AS-OCT these values were 0.629 and 0.859, respectively. UBM had a higher reproducibility in both PIT and IC measurements as compared with AS-OCT. Differences in PIT measurement between AS-OCT and UBM (P = 0.331) were not statistically significant, the 95% LoA (-0.178-0.156) mm was 36.1-41.2% of the mean. The IC was 0.053 mm smaller when measured by UBM than by AS-OCT (P = 0.017), with the 95% LoA (-0.100-0.206) mm, or 36.2-74.6% of the mean.

CONCLUSION

UBM had a higher reproducibility in measuring iris parameters than AS-OCT. The consistency between AS-OCT and UBM in measuring iris parameters was low in primary angle closure glaucoma patients.