THICKNESS OF THE MACULA, RETINAL NERVE FIBER LAYER, AND GANGLION CELL–INNER PLEXIFORM LAYER IN THE AGE-RELATED MACULAR DEGENERATION

Purpose: To determine the repeatability of measuring the thickness of the central macula, retinal nerve fiber layer, and ganglion cell–inner plexiform layer (GC-IPL) using spectral domain optical coherence tomography (Cirrus HD-OCT) in eyes with age-related macular degeneration. Methods: One hundred and thirty-four eyes were included. The measurement repeatability was assessed by an experienced examiner who performed two consecutive measurements using a 512 × 128 macular cube scan and a 200 × 200 optic disk cube scan. To assess changes in macular morphology in patients with age-related macular degeneration, the patients were divided into the following three groups according to the central macular thickness (CMT): A group, CMT < 200 μ m; B group, 200 μ m ≤ CMT < 300 μ m; and C group, CMT > 300 μ m. Results: Measurement repeatability was assessed using test–retest variability, a coefficient of variation, and an intraclass correlation coefficient. The mean measurement repeatability for the central macular, retinal nerve fiber layer, and GC-IPL thickness was high in the B group. The mean measurement repeatability for both the central macula and retinal nerve fiber layer thickness was high in the A and C groups, but was lower for the GC-IPL thickness. The measurement repeatability for GC-IPL thickness was high in the B group, but low in the A group and in the C group. Conclusion: The automated measurement repeatability for GC-IPL thickness was significantly lower in patients with age-related macular degeneration with out of normal CMT range. The effect of changes in macular morphology should be considered when analyzing GC-IPL thicknesses in a variety of ocular diseases.