Determination of Referential Rates for Optical Coherence Tomography and Optical Coherence Tomography Angiography Flow Deficits in the Macular Choriocapillaris in Ophthalmologically Healthy Children

Abstract

Background and Objectives: Despite the growing number of new research publications, normative references for children's optical coherence tomography (OCT) parameters are still not completed. We chose to explore this topic because of the lack of normative parameters that is due to an improvement in different technologies and instruments. Our aim was to determine referential rates of retinal nerve fiber layer (RNFL) thickness and flow deficits (FD%) in the macular choriocapillaris (CC) in normal eyes of ophthalmologically healthy children. Materials and Methods: Ophthalmologically healthy 8- to 14-year-old individuals participated (n = 75) in this study. OCT images were taken using an swept-source-OCT (SS-OCT) instrument (DRI-OCT Triton, Topcon, Tokyo, Japan). The early treatment diabetic retinopathy study (EDTRS) grid (6 × 6 mm) divided the RNFL into the thickness maps. The FD% values of the CC were calculated on the 3 × 3-mm scans in a 1-mm circle (C₁), 1.5-mm rim (R_1.5), and the entire 2.5-mm circle (C_2.5), and on the 6 x 6-mm scans in a 1-mm circle (C₁), 1.5-mm rim (R_1.5), the entire 2.5-mm circle (C_2.5), 2.5-mm rim (R_2.5), and 5-mm circle (C₅). Results: Both scan quantifications of FD% in the C₁, C_2.5, and R_1.5 sectors were similar, but the 6 × 6-mm scan measurements were statistically significantly smaller than the 3 × 3-mm ones. Significant moderate correlations were found between axial length (AxL) and FD% in the 6 × 6-mm scans, namely C₁ (r = -0.347, p = 0.002), C_2.5 (r = -0.337, p = 0.003), R_1.5 (r = -0.328, p = 0.004), R_2.5 (r = -0.306, p = 0.008), and C₅ (r = -0.314, p = 0.006). Conclusions: The thinnest RNFL layers were on the temporal and nasal sides. FD% values in the C₁, C_2.5, and R_1.5 sectors were similar between the 3 × 3-mm and 6 × 6-mm scans. The negative moderate correlations between AxL and FD% were found in all C₁, C_2.5, C_5, R_1.5, and R_2.5 sectors of the 6 × 6-mm scans. Further prospective studies are needed to determine more accurate normative references for children's OCT parameters.

Keywords: choriocapillaris; flow deficits; ophthalmologically healthy children; optical coherence tomography angiography; retinal nerve fiber layer; swept-source optical coherence tomography.