Clinical Assessment of Scleral Canal Area in Glaucoma Using Spectral-Domain Optical Coherence Tomography

Purpose: To investigate anterior scleral canal (ASC) area in the eyes with glaucoma using spectral-domain optical coherence tomography (SDOCT). Design: Cross-sectional study. Methods: This study included 206 eyes of 103 patients with glaucoma, classified as 66 eyes of 33 patients with unilateral glaucoma and 140 eyes of 70 patients with bilateral glaucoma. Radial scan enhanced depth imaging SDOCT centered on the optic disc was performed, and parameters that present ASC area such as ASC opening and the largest ASC area were obtained in each eye. The largest ASC area was the largest cross-sectional area of the ASC region identified between the ASC opening and anterior lamina cribrosa insertion. These parameters were compared between eyes with and without glaucoma in unilateral glaucoma, and eyes with worse and better visual field defect (VFD) in bilateral glaucoma. Results: In the patients with unilateral glaucoma, ASC opening and largest ASC area were significantly larger in the eyes with glaucoma than in those without glaucoma (both P < .001). In bilateral glaucoma, these parameters were significantly larger in the eyes with worse VFD than in those with better VFD (P = .0080 and P = .0018, respectively). Intereye differences of the ASC parameters in the glaucoma patients were significantly greater than that in the normal subjects. Conclusions: Significantly larger ASC area was first observed in the living human eyes with glaucoma compared to the normal eyes. Further longitudinal studies are required to determine if the ASC area is useful in the prevention and treatment of glaucoma.