Posterior staphyloma is related to optic disc morphology and the location of visual field defect in normal tension glaucoma patients with myopia

Purpose To determine the morphologic features of the optic disc and the location of visual field (VF) defect in relation to posterior staphyloma in normal tension glaucoma (NTG) eyes with myopia. Methods One hundred and thirty-four NTG patients with myopia were enrolled. B-scan ultrasonography was performed in enrolled patients. Disc tilt ratio, disc torsion, and area of peripapillary atrophy were measured from disc photographs. Patients were classified according to the presence of posterior staphyloma and its location: staphyloma involving the optic disc, staphyloma involving either the supero-temporal side of the optic disc or the infero-temporal side of the optic disc. The relationship between the location of the posterior staphyloma and that of the VF defect was analyzed. Results Among 134 eyes, 74 eyes (55.2%) had posterior staphyloma on B-scan ultrasonography. Mean torsion degree was significantly greater in eyes with staphyloma involving the temporal side of the optic disc (19.78 +/- 18.00 degrees) compared with eyes with staphyloma involving the optic disc (4.65 +/- 4.92 degrees, P = 0.001). The frequency of the location of VF damage differed significantly between eyes with staphyloma involving the supero-temporal side and those involving the infero-temporal side of the optic disc (P = 0.008), which was not significant in eyes with staphyloma involving the optic disc (P = 0.813). Conclusions Optic disc torsion was a prominent finding in myopic NTG eyes when posterior staphyloma was located temporal to the optic disc. The location of posterior staphyloma was related to the direction of disc torsion and the location of VF defect.