Optic Nerve Sheath Diameter in Glaucoma Patients and its Correlation with Intraocular Pressure

Abstract

Aim: To compare optic nerve sheath diameter (ONSD) in primary open angle glaucoma (POAG), primary angle closure glaucoma (PACG) and normal tension glaucoma (NTG). Material and Methods: Patients with POAG (n=38), PACG (n=32), NTG (n=18) and con-trols (n=48) underwent B-scan ultrasound and computed tomography scan (CT scan) measurement of ONSD. Intraocular pressure (IOP) was measured in all groups and was correlated with ONSD. Results: ONSD was significantly (p=<0.001) increased in NTG patients (mean=5.0 mm ± 0.48 SD) compared with POAG (mean=4.20 mm ± 0.32), PACG (mean=4.33 mm ± 0.27) and control (mean=4.21 mm ± 0.31). ONSD showed correlation with IOP in PACG group (r=0.392, p=0.02) while it did not in other groups. Conclusion: ONSD in a group of NTG patients were significantly increased compared with POAG, PACG and controls indicating the role of translaminar cribriform pressure gradient in NTG patients. Indirect measurement of ICP by assessment of ONSD may provide further insight into retrolaminar pressure component and pathophysiology of glaucoma.