Reproducibility of thickness measurements of macular inner retinal layers using SD-OCT with or without correction of ocular rotation.

Purpose

To evaluate the intervisit reproducibility of spectral-domain optical coherence tomography (SD-OCT) measurement of the macular retinal nerve fiber layer thickness (mRNFLT); combined ganglion cell layer and inner plexiform layer (GCL+IPL) thickness; and ganglion cell complex (GCC) thicknesses (sum of mRNFLT and GCL+IPL thicknesses) compared with that of circumpapillary RNFLT (cpRNFLT) and the effect of ocular rotation on reproducibility.

Methods

SD-OCT imaging was performed twice on different days in one eye of 58 normal subjects and 73 glaucoma patients. The reproducibility was evaluated for the entire 4.8-mm × 4.8-mm macular area and subareas (upper and lower halves, 2 × 2, 4 × 4, and 8 × 8 grids), and the 360°, upper, and lower halves mean cpRNFLT with and without correction of ocular rotation.

Results

The coefficients of variation (CVs) of GCL+IPL and GCC thickness measurements averaged below 1.0% for the entire and upper and lower half macular areas, and below 4.2% in the macular subareas in normal and glaucoma eyes, which were significantly smaller (P < 0.001) than those of mRNFLT measurements in the same areas of the same eyes. The CVs of mRNFLT measurements were significantly smaller than those of the cpRNFLT only in the lower half mean area in normal eyes. The reproducibility was minimally affected by correction of ocular rotation or presence of glaucoma.

Conclusions

The reproducibility of the macular (GCL+IPL) and GCC thickness measurements was better than that of mRFNLT and cpRNFLT in normal and glaucoma eyes and minimally affected by correction of ocular rotation.