Relative lens vault in subjects with angle closure

BACKGROUND The purpose of this study was to investigate the association of a novel biometric parameter, relative lens vault (LV), with primary angle-closure (PAC) and primary angle-closure glaucoma (PACG). METHODS We evaluated 101 subjects with PAC (G) and 101 normal subjects that were age- and gender-matched. Based on anterior-segment optical coherence tomography scans, and using customized software, the anterior vault (AV) and LV were measured. They were defined as the maximum distances between the horizontal line connecting the two scleral spurs and the posterior corneal surface and anterior lens surface, respectively. The relative LV was calculated by dividing the LV by the AV. RESULTS Significant differences between PAC (G) eyes and normal eyes were found in the LV (1.06 ± 0.41 vs. 0.36 ± 0.37 mm, P < 0.001), relative LV (0.34 ± 0.23 vs. 0.11 ± 0.25, P < 0.001), and axial length (22.96 ± 0.94 vs. 24.02 ± 1.33 mm, P < 0.001). However, the two groups' values of the AV relative to those of axial length were quite similar (both 0.14 ± 0.03, P = 0.91). The relative LV values distinguished between PAC (G) eyes and normal eyes better than the LV values (area under the receiver operator characteristic curve: 0.97 vs. 0.92, P = 0.032). CONCLUSIONS Our results suggest that relative dimensions of the eyeball's anterior portion in PAC (G) eyes might be within the normal range. And the value of LV relative to that of the AV (i.e., the relative LV) is more closely related to PAC (G) than is the absolute value of LV.