Macular Inner and Total Retinal Volume Measurement by Spectral Domain Optical Coherence Tomography for Glaucoma Diagnosis

Abstract

Purpose: : Comparison between performance of inner and total retinal volume of macula measured by spectral-domain optical coherence tomography to discriminate glaucomatous and normal eyes.

Methods: : We examined 49 eyes of 33 open-angle glaucoma patients and 61 eyes of 35 normal subjects using RTVue-100 (software version 1.2.6;Optovue) by employing a scan protocol of MM5 to measure the inner retinal volume and total retinal volume. Inner retinal volume was defined as the volume between the vitreoretinal interface and the outer border of the inner plexiform layer. The correlation between the mean volume within 1-, 3-,and 5-mm circular retinal area and the mean deviation (MD) of standard automated perimetry (Humphrey field analyzer and 24-2 /30-2 Swedish Interactive Thresholding Algorism Standard) was analyzed using Spearman’s correlation coefficient. The ability to discriminate glaucomatous from normal eyes was assessed by the area under the receiver operating characteristic curves (AUROC).

Results: : The mean volume in the 1-mm circular area did not differ significantly between the glaucomatous and normal eyes. In the 3- and 5-mm circular areas, the mean inner retinal volume in the glaucoma group showed statistically significant thinning of 11.5% and 14.6%, respectively, versus the normal group (both, P < 0.001). In the 3- and 5-mm circular areas, the mean total retinal volume in the glaucoma group showed statistically significant thinning of 3.5% and 6.3%, respectively, versus the normal group (P = 0.001 and P < 0.001, respectively). The inner and total retinal volume significantly correlated with the MD values only in the 3- and 5- mm circular areas, and the inner retinal volume (3-mm: r_s = 0.656, P < 0.001; 5-mm: r_s = 0.587, P < 0.001) showed a better correlation with the MD values than the total retinal thickness (3-mm: r_s = 0.416, P = 0.001; 5-mm: r_s = 0.380, P = 0.007). The Inner retinal volume in the 5-mm circular area had the largest AUROC (AUROC of the inner retinal volume in the 1-, 3-, and 5-mm circular areas: 0.521, 0.795, and 0.905, respectively; AUROC of the total retinal volume within the 1-, 3-,and 5-mm circular areas:0.399, 0.684, and 0.808, respectively).

Conclusions: : The inner retinal volume showed greater thinning, a stronger correlation with the MD values, and a better performance than the total retinal volume to discriminate glaucomatous and normal eyes. Thus, it may be a promising parameter for glaucoma diagnosis.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina • imaging/image analysis: clinical