Comparison of Diagnostic Power of Optic Nerve Head and Posterior Sclera Configuration Parameters on Myopic Normal Tension Glaucoma.

PURPOSE

The aim of this study was to compare the diagnostic power of optic nerve head and posterior scleral configuration parameters obtained with the swept-source optical coherence tomography (SSOCT) on myopic normal-tension glaucoma (NTG).

MATERIALS AND METHODS

A total of 203 eyes of 203 participants with myopia diagnosed at Seoul Saint Mary's Hospital between September 2016 and February 2018 were divided into myopic NTG group (n=113) and nonglaucomatous myopia group (n=90). Established optic nerve head (ONH) parameters such as disc torsion, horizontal tilt, and vertical tilt, and novel parameters representing posterior sclera, were quantified using SSOCT. The posterior sclera was presented with the relative position of the deepest point of the eye (DPE) from the optic disc by measuring the distance, depth, and angle. The mean and the statistical distribution of each index were calculated. Differences in distribution led to another novel marker, absolute misaligned angle, which represents the displaced direction of the ONH from the sclera. The ONH was classified as misaligned when the degree of misalignment was >15 degrees in either direction. The area under the receiver operating characteristic curves and multivariate logistic regression analysis were used to test the diagnostic power in the presence of myopic NTG.

RESULTS

No significant difference was observed with respect to age, sex, refractive error, axial length, and central corneal thickness between the 2 groups. However, 20 (22.22%) of 90 eyes in the nonglaucomatous group showed misalignment, whereas 60 (53.09%) of 113 eyes in the NTG group had misalignment (odds ratio: 3.962, P<0.001). The absolute misaligned angle (0.696) and the horizontal tilt (0.682) were significantly associated with myopic NTG, which significantly exceeded other parameters in area under the receiver operating characteristic curves (both P<0.001). The multivariate logistic regression also showed that the absolute misaligned angle (hazard ratio=1.045, 95% confidence interval=1.023-1.068, P<0.001) and the horizontal tilt (hazard ratio=1.061, 95% confidence interval=1.015-1.109, P=0.009) were associated significantly with the presence of NTG.

CONCLUSIONS

The diagnostic power of absolute misaligned angle and the horizontal tilt angle significantly exceeded other parameters on myopic NTG. These parameters may be associated with a displaced direction of the ONH to the posterior sclera, which can be linked to the altered sclera configuration of myopic NTG subjects.