Retinal volume assessment using wide-field swept-source optical coherence tomography in eyes without retinal disease

Abstract

Purpose : The purpose of this study was to evaluate retinal volume (RV) in eyes without retinal disease using wide-field swept-source optical coherence tomography (SS-OCT), and assess the association between RV and other variables.

Methods : Cube scans (20 × 23 mm) of the eyes were taken using the OCT-S1 (Canon) instrument and assessed. A fovea-centered 20-mm diameter retinal thickness map was manually generated by applying the original grid with the 6-mm and 20-mm circle (Figure 1). The mean retinal thickness in each subfield was measured using an OCT extractor and a map viewer built into the instrument, and these measurements were converted to RVs. Associations between RV (6 mm and 20 mm), sex, age, laterality, axial length, and complete posterior vitreous detachment (PVD) in paired eyes were assessed using a generalized estimating equation model for multivariate analysis. Pearson's correlation coefficient was used to evaluate the correlation between the 6- and 20-mm diameter RVs.

Results : The study included 87 males and 116 females (mean age 42.5 ± 24.8 years). Their right and left eye axial lengths were 25.1 ± 1.3 mm and 25.0 ±1.4 mm, respectively. Complete PVD was observed in 53 right and 52 left eyes. The 6-mm diameter RVs were 8.5 ± 0.8 mm³ and 8.5 ± 0.9 mm³, while the 20-mm diameter RVs were 73.3 ± 5.7 mm³ and 73.1 ± 6.0 mm³ (for the right and left eyes, respectively). Multivariate analysis showed that age (p < 0.001) and PVD (p < 0.001) were significantly associated with the 6-mm diameter RV (Figure 2). Female sex (p = 0.04), age (p < 0.001), and PVD (p = 0.002) were significantly associated with the 20-mm diameter RV (Figure 2). There was also a positive correlation between the 6- and 20-mm diameter RVs (right: r = 0.91, p < 0.0001, left: r = 0.89, p < 0.0001).

Conclusions : Female sex, old age, and the presence of complete PVD correlated with smaller retinal volume in the 20-mm diameter.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Figure 1. Color map of the application of the original grid to the retinal thickness. The retinal volume is calculated by the following formula.
Mean retinal thickness × Subfield's area = Retinal volume
ex. 314.0 μm × 28.2 mm2 = 8.9 mm3 (6 mm circle)
8.9 mm3 + 250.5 μm × 285.9 mm2 = 80.5 mm3 (20 mm circle)
Color is based on the absolute retinal thickness, and is indicated by the color bar.

 

Effect of age on the 6-mm and 20-mm diameter retinal volumes.