Topographical variation of macular choroidal thickness with myopia

Purpose To study the association between topographical variation of choroidal thickness and myopic features in healthy eyes, using spectral domain optical coherence tomography (OCT). Methods Choroidal thickness was measured at the foveal centre (CTF) and 1.5 mm superiorly (CTS), inferiorly (CTI), nasally (CTN) and temporally (CTT) from the foveal centre, using enhanced depth imaging OCT. The temporal width of β zone of peripapillary atrophy (βPPA) was measured on infrared fundus images. The ratio of βPPA width to vertical disc diameter (PVDR) was calculated to correct retinal magnification. Results This study includes 85 eyes from 85 subjects who had a mean age of 53.9 ± 12.9 years, a mean axial length of 23.56 ± 0.82 mm, a mean refractive error of -0.14 ± 1.80 D, a mean βPPA width of 218.6 ± 181.3 μm and a mean PVDR of 0.13 ± 0.11. The CTF was thickest (266.4 ± 81.6), followed by CTS (256.2 ± 82.5 μm), CTT (251.7 ± 68.4 μm), CTI (247.7 ± 90.3 μm) and CTN (211.0 ± 76.5 μm). There were 31 eyes (36.5%) with CTT thicker than CTF. The CTT/CTF negatively correlated with refractive error (p = 0.012) and positively correlated with axial length (p = 0.031), βPPA width (p = 0.003) and PVDR (p = 0.006). Conclusions There was a correlation between a thickened choroid, temporal to the foveal centre, with the severity of myopic components in normal eyes. Topographical changes might be induced by stretching of the choroid and sclera towards a temporal direction with eyeball elongation.