Novel screening method for glaucomatous eyes with myopic tilted discs: the crescent moon sign.

Abstract

To our knowledge, there is no reliable screening method for glaucomatous eyes with myopic tilted discs. To evaluate the diagnostic ability of a novel screening modality, the crescent moon (CM) sign, defined as the discontinuity between the superior or inferior optic rim margin and the temporal optic rim margin, for the detection of glaucomatous eyes with myopic tilted discs. The study was cross-sectional and conducted in a hospital setting from November 1, 2011, to November 1, 2013. Seventy eyes of 70 individuals with early open-angle glaucoma (mean deviation greater than -6 dB) and 70 eyes of 70 normal control participants who had myopic tilted discs were recruited. Another independent group consisting of 60 eyes of 60 individuals with early glaucoma and 60 eyes of 60 normal control participants was enrolled. Two masked glaucoma specialists independently assessed the optic disc on stereoscopic disc photography. The diagnostic performance of the CM sign was evaluated in comparison with violation of the ISNT rule (inferior ≥ superior ≥ nasal ≥ temporal order of configuration for disc rim thickness in normal eyes) and the modified ISNT rule (application of the ISNT rule based on the long axis of the disc). Sensitivity and specificity of the CM sign. The CM sign was more frequently observed in the inferotemporal optic rim margin than in the superotemporal optic rim margin. In a comparative evaluation of the glaucoma diagnostic sensitivity and specificity, the CM sign showed higher sensitivities (90.0%-91.4%) than the ISNT rule (73.3%-75.7%) or the modified ISNT rule (68.6%-70.0%). The CM sign also showed higher specificities (82.9%-83.3%) than the ISNT rule (68.3%-71.4%) or the modified ISNT rule (76.6%-80.0%). Furthermore, the CM sign was shown to be associated with the occurrence of visual field defects in the corresponding hemifield (P < .001). The CM sign can be a useful screening tool for the detection of early glaucoma with myopic tilted discs.