Biometric characteristics of eyes with exfoliation syndrome and occludable as well as open angles and eyes with primary open-angle glaucoma

Objective: To describe differences in axial length scan (A-scan) and ultrasound biomicroscopy (UBM) parameters in eyes with exfoliation syndrome (XFS) and occludable angles (XFSOc), XFS and open angles (XFSOp), and eyes with primary open-angle glaucoma (POAG). Design: Cross-sectional descriptive study. Participants: Seventy-two eyes of 72 patients (mostly Caucasians) were identified through glaucoma clinics at the University of Ottawa;19 eyes had XFSOc, 31 eyes XFSOp, and 22 eyes POAG. Methods: After a detailed ophthalmic history and examination, A-scan biometry and UBM were done to assess anterior segment parameters: central anterior chamber depth (ACD), lens thickness, trabecular meshwork-iris angle, and angle opening distance (AOD). Lens/axial length factor and the relative lens position were calculated. The above measurements were compared across the 3 groups. Results: We found statistically significant differences in measurements among the groups. ACD was shallowest in eyes with XFSOc (1.88 [SD 0.07] mm), followed by XFSOp (2.37 [SD 0.05] mm), and POAG (2.64 [SD 0.08] mm). XFSOc had thicker lenses (5.28 [SD 0.09] mm) compared with the other groups: XFSOp (5.03 [SD 0.06] mm) and POAG (4.84 [SD 0.09] mm). Lens/axial length factor was highest in XFSOc (2.34 [SD 0.05] mm) versus XFSOp (2.12 [SD 0.03] mm) and POAG (2.02 [SD 0.05] mm); relative lens position was lowest in XFSOc (2.27 [SD 0.03] mm) versus XFSOp (2.31 [SD 0.02] mm) and POAG (2.36 [SD 0.03] mm). Conclusions: Eyes with XFSOc in our study demonstrated lens thickening and shallow central ACD versus eyes with XFSOp and eyes with POAG. This suggests the possibility that cataract formation and (or) zonular weakness may contribute to the development of an occludable angle in eyes with XFS.