Abstract
Purpose :
Glaucomatous cupping of the optic nerve head is caused by backward bowing of the lamina cribrosa and lateral expansion of the anterior scleral canal (ASC). The previous studies regarding ASC expansion were limited mostly to the animal experimental glaucoma by using histological method. We conducted a study to test the hypothesis that ASC would expand in the living human eyes with glaucoma by using spectral-domain optical coherence tomography (SD-OCT).
Methods :
This cross-sectional 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. One hundred eyes of 50 normal subjects were included as controls. Radial scan enhanced depth imaging SD-OCT centered on the optic disc was performed, and parameters that present ASC area such as ASC opening and largest ASC area were obtained in each eye. 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. Inter-eye differences of the ASC parameters in the glaucoma patients were compared with those in the normal subjects to examine if they exceeded normal variation.
Results :
In 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, the ASC opening and largest ASC area were significantly larger in the eyes with worse VFD than in those with better VFD (P = .0080 and .0018, respectively). Inter-eye differences of the ASC parameters in the glaucoma patients were significantly greater than that in the normal subjects (P < .001 for both ASC opening and largest ASC area in unilateral glaucoma, and P = .0145 and .0037, respectively, in bilateral glaucoma).
Conclusions :
Significant expansion of the ASC area was first observed in the living human eyes with glaucoma. The ASC area may be useful in monitoring development and progression of the optic disc deformation in glaucoma.
This is a 2020 ARVO Annual Meeting abstract.