Interindividual Variations in Foveal Anatomy and Artifacts Seen on Inner Retinal Probability Maps from Spectral Domain OCT Scans of the Macula

PURPOSE: We tested the hypothesis that variations in foveal morphology can account for artifacts seen on optical coherence tomography (OCT) retinal ganglion cell (RGC) layer probability maps. METHODS: A total of 126 healthy subjects were tested with spectral domain (sd) OCT. Thickness and probability maps of the macular RGC plus inner plexiform layer (RGC+) were obtained with customized software. Macular b-scans were analyzed to derive three foveal anatomic parameters: width, depth, and slope. The distribution of these parameters was compared between eyes with and without circumfoveal artifacts seen in the central 4° of macular RGC+ probability maps. RESULTS: Of 126 healthy subjects, 12 (9.5%) had an abnormal circumfoveal region (artifact) on RGC+ probability maps. Based upon the normal distribution of the three anatomic parameters, only three of the 12 eyes (25%) fell outside the 95% confidence interval of one or more of the three foveal morphologic parameters. Multivariable logistic regression revealed that the parameter slope was significantly associated with the presence of these artifacts (odds ratio = 0.26; P = 0.019). However, the combination of these parameters and age explained only 11% of the total variance of these artifacts. CONCLUSIONS: Fovea morphology, as measured based upon width, depth, and slope, has a minor role in explaining artifacts seen on macular scans. Variations in the distribution of RGC+ thickness that are not reflected in our measures warrant further investigation as potential sources of artifacts. TRANSLATIONAL RELEVANCE: A small proportion of circumfoveal artifacts seen on RGC+ probability maps can be explained by variations in foveal anatomy.