Measurement of macular ganglion cell layer and circumpapillary retinal nerve fiber layer to detect paracentral scotoma in early glaucoma.

BACKGROUND

Glaucoma patients with paracentral scotoma are at higher risk of losing central vision than those without glaucoma. The purpose of this study was to determine whether macular inner retinal layer (MIRL) measurements with spectral-domain optical coherence tomography (SD-OCT) outperform circumpapillary retinal nerve fiber layer (cpRNFL) measurements in discriminating between eyes with and without paracentral scotoma.

METHODS

This retrospective study included 63 early glaucomatous eyes of 63 patients with (PSI group) or without (PSF group) paracentral visual field (VF) defects. MIRL thicknesses, including macular ganglion cell complex (mGCC), macular ganglion cell layer + inner plexiform layer (mGCL+), macular RNFL (mRNFL), and cpRNFL thickness were measured using a SD-OCT instrument (3D OCT-2000). The MIRL and cpRNFL were divided into 50 grid cells and 36 sectors, respectively, which were numbered from center/temporal to periphery/nasal. Discriminating ability of the methods for number of cells/sectors with abnormal thickness (<5% of normal) and average thickness in the hemisphere corresponding to the VF defects (termed hemi-thickness) was compared by area under the receiver operating characteristics curves (AROCs).

RESULTS

The number of abnormal nearest sectors of cpRNFL and all MIRL parameters were significantly smaller in the PSI group than in the PSF group (P ≤ 0.001-0.047), whereas no significant differences were found for average or hemi-cpRNFL thickness. The AROCs of the number of abnormal nearest cells for mGCC and mGCL+ and average hemi-thickness for mGCC, mGCL+, and mRNFL were comparable and significantly higher than those of the number of abnormal nearest sectors/cells for cpRNFL (P = 0.0002-0.0063) and mRNFL (P = 0.0003-0.0267) parameters.

CONCLUSIONS

Regional assessment of MIRL thickness as measured by SD-OCT may potentially be an effective method for predicting central involvement of VF defects in early glaucoma.