Normative Data for Retinal-Layer Thickness Maps Generated by Spectral-Domain OCT in a White Population

Purpose (1) To collect a dataset of normative Early Treatment Diabetic Retinopathy Study (ETDRS) thickness map values for single retinal layers automatically segmented by Spectralis (Heidelberg Engineering, Heidelberg, Germany) spectral-domain OCT (SD-OCT) in a healthy white population. (2) To test the effect of age, sex, and axial length (AXL) on such values. Design Cross-sectional study. Subjects Healthy adult emmetropic white subjects with no history of ongoing or past conditions known to affect retinal anatomy. Methods SD-OCT scans (30 × 25-degree volume) centered on the fovea were collected. Retinal-layer automatic segmentation was performed. Mean thickness values of 9 ETDRS sectors were calculated for each layer in 1 eye from each subject. The effect of age, sex, and AXL on the thickness of the central subfield, inner ring (IR), and outer ring (OR) of the ETDRS grid was tested. Scans were performed twice on a subset of patients to assess the repeatability of measurements. Main Outcome Measures Retinal-layer thickness. Results Two hundred eyes from 200 subjects (110 females, mean age 39.9±13.9 years [range 20–74 years]) were used for this study. The mean AXL was 24.30±1.07 mm (range 22.23–27.14 mm). Full retinal thickness was higher in males regardless of the subfield (all P < 0.05). Ganglion cell layer thickness correlated positively with AXL in the C (P = 0.02) but negatively in the OR (P = 0.0001). The inner plexiform layer was thicker in males in the IR (P = 0.01) and thinner in longer eyes in the OR (P = 0.002). The inner nuclear layer was thicker in males in the C and the IR (P = 0.002 and P = 0.0009, respectively). The outer plexiform layer thickness did not change with age and gender but correlated positively with AXL in the C (P = 0.009). Males had thicker outer nuclear layers in all subfields (all P < 0.05). The thickness of the nerve fiber layer and retinal pigment epithelium was not affected by the studied variables in any subfield. The intraclass correlation coefficient ranged from 0.872 for the outer plexiform layer to 0.990 for the retinal nerve fiber layer and the ganglion cell layer. Conclusions The thickness values of each retinal layer in a large white population are provided. The thickness of retinal layers is influenced by gender, sex, and AXL, with a variable extent depending on the analyzed ETDRS map ring.