To identify the impact of the presence of peripheral anterior synechia (PAS) on the depth of the anterior segment in patients with a shallow anterior chamber after laser iridotomy (LI) by analyzing changes in the anterior segment biometry using ultrasound biomicroscopy (UBM).

Twenty eyes of 20 patients with PAS and shallow anterior chamber, and another 20 eyes of 20 patients with shallow anterior chamber without PAS were studied. The changes in the anterior segment biometry for each group of patients were examined using gonioscopy and UBM before and after the LI.

The central corneal thicknesses and scleral thicknesses of the two groups did not show significant differences ( p > 0.05). The anterior chamber depths, anterior chamber angles, trabecular meshwork-iris distances, and angle-opening distances 500 increased significantly after the peripheral LI ( p < 0.05) in both groups. However, the difference in the increases in the anterior segment biometries between the two groups was not statistically significant.

LI can increase the depth of the anterior chamber regardless of the presence of PAS.