Improved diagnostic performance of an optical coherence tomography-derived neuroretinal rim parameter in myopic eyes.

Abstract

Purpose: The morphology of optic discs in myopic individuals often poses a significant challenge for the diagnosis of glaucoma. A novel parameter measuring the minimum distance from Bruch's membrane opening (BMO) to the internal limiting membrane (BMO-MRW) has shown promise as a diagnostic tool. The aim of this study was to compare the diagnostic performance of BMO-MRW to the conventional disc margin based neuroretinal rim measurement derived from confocal scanning laser tomography (CSLT) in myopic eyes.

Methods: Healthy myopic controls and glaucoma myopic patients with a spherical equivalent refractive error of at least -2.0 D and with typical myopic tilted discs, defined by the presence of large areas of beta-zone peripapillary atrophy in the temporal area, were enrolled in this study. The diagnosis of glaucoma was based on a consensus evaluation by three masked observers of optic disc photographs and visual field tests. All subjects were imaged with SD-OCT (Spectralis) and CSLT (Heidelberg Retina Tomograph - HRTIII). OCT high-resolution 15° radial scans centered on BMO were acquired; BMO and internal limiting membrane were automatically delineated and the BMO-MRW computed. Rim area (RA) was calculated for the HRT, after the contour line was manually delineated by one masked observer. Global RA and global BMO-MRW were utilized for analysis; their diagnostic performance was assessed by comparing receiver operating characteristic (ROC) curves and evaluating sensitivity with a fixed specificity of 90%.

Results: The mean (±sd) age and refractive error of 30 glaucoma patients (62 ± 12 years; -6 ± 3D) was similar to 34 healthy volunteers (60 ± 13 years; -6 ± 2D). The area under the ROC curve was significantly higher (Z=4.5; p<0.001) for BMO-MRW (0.91; 95% CI: 0.81—0.97) compared to RA (0.57; 95% CI: 0.44—0.69). The sensitivity at a fixed specificity of 90% was 73% (95% CI: 54—88) for the BMO-MRW and 23% (95% CI: 10—42) for RA.

Conclusions: The OCT-derived parameter BMO-MRW has better diagnostic accuracy than the HRT-derived RA in myopic tilted eyes. The BMO-MRW is a potentially useful diagnostic tool in myopic eyes.

Keywords: 605 myopia • 550 imaging/image analysis: clinical • 627 optic disc