Diagnostic Ability of Posterior Pole Asymmetry Analysis of Spectral-domain Optical Coherence Tomography to Detect Localized Retinal Nerve Fiber Layer Defects

Abstract

Purpose: : To investigate the diagnostic ability of posterior pole asymmetry analysis (PPAA) of the spectral domain optical coherence tomography (SD-OCT; Spectralis OCT, Heidelberg) to detect localized retinal nerve fiber layer (RNFL) defects.

Methods: : Prospective, observational case series of 84 open-angle glaucoma subjects (84 eyes) with localized, wedge-shape RNFL defects by red-free RNFL photographs and 122 eyes of normal subjects. The subjects were examined by Spectralis OCT to obtain circumpapillary RNFL (cpRNFL) thickness as well as PPAA. The PPAA provides a corresponding cell to cell comparison between fellow eyes and hemispheres within each eye and presents the difference using gray scale (differences > 30μm is shown in black). Area under the receiver operating characteristic curve (AUROC), the sensitivity and specificity of PPAA to detect glaucoma with the localized defects was examined using various criteria; 2 consecutive black cells (Criterion A), 3 consecutive black cells (Criterion B), and 4 consecutive black cells (Criterion C).

Results: : An AUROC of PPAA of black cell was 0.958 ± 0.013. The sensitivity and specificity of PPAA were 95.2% and 81.1% for criterion A, respectively; 83.3% and 92.6% for criterion B; and 69.0% and 98.4% for criterion C. The sensitivity and specificity of the cpRNFL thickness using OCT with criterion more than 1 sector abnormality at 99 % confidence interval (CI) were 85.7% and 95.1%, respectively. These values were comparable with sensitivity (P=0.824) and specificity (P=1.000) obtained from the PPAA using criterion B.

Conclusions: : The PPAA of Spectralis OCT can detect localized RNFL defects with high sensitivity and specificity, which are comparable with the cpRNFL thickness profile of OCT with 99 % CI. These findings suggest that the PPAA can be complementary to other test for diagnosing glaucoma in patients with localized RNFL defect.

Keywords: imaging/image analysis: clinical • ganglion cells • optic nerve