Disc–fovea distance and choroidal thickness: is there a relationship?

Background: The distance between the optic disc center and the fovea is a biometric parameter; however, it is unclear whether DFD (disc–fovea distance) affects the choroidal thickness. Objective: The aim of this study is to investigate the association between DFD and choroidal thickness. Design: This is a prospective, and cross-sectional study. Methods: Two hundred fifty eyes of 250 healthy participants were examined in terms of DFD, age, axial length, spherical equivalent, and choroidal thickness. Inclusion criteria included aged between 20–40 years, no posterior segment disorders, and participants with best-corrected visual acuity (10/10 according to Snellen’s chart). Participants with high hypermetropia (>4 diopter) or myopia (>6 diopter) or any systemic disease likely to affect choroidal thickness were excluded. Choroidal thickness measurements were performed at subfoveal, 1.0 mm temporal, and 1.0 mm nasal using the enhanced-depth imaging optical coherence tomography. Results: The mean age of all the participants was 26.21 ± 5.73 years, mean DFD was 4634.29 ± 274.70 µm, mean axial length was 23.62 ± 0.83 mm, and mean spherical equivalent was −0.61 ± 1.06 diopter. The mean subfoveal, nasal, and temporal choroidal thicknesses were 388.73 ± 90.15 µm, 351.26 ± 88.09 µm, and 366.50 ± 79.56 µm, respectively. A negative correlation was found between subfoveal, nasal, and temporal choroidal thicknesses and axial length (r = −0.157, p = 0.013; r = −0.168, p = 0.008; r = −0.174, p = 0.006, respectively). Insignificant correlation was found between choroidal thicknesses and spherical equivalent (p > 0.05). There was not a statistically significant correlation between DFD and subfoveal, nasal, and temporal choroidal thicknesses (r = −0.028, p = 0.655; r = 0.030, p = 0.641; r = −0.025, p = 0.699, respectively). In addition, there was not a statistically significant correlation between age and choroidal thickness. Conclusion: This study shows that DFD and spherical equivalent do not affect choroidal thickness; axial length negatively affects choroidal thickness. In addition, age does not affect choroidal thickness between 20 and 40 years.