Purchase this article with an account.
Ari Shinojima, Mitsuko Yuzawa; Choroidal thickness at various sites during head-down tilt. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3414.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
We previously reported subfoveal choroidal thickness and intraocular pressure to increase during the simulated microgravity of 10-degree head-down-tilt (HDT), possibly causing hyperopic shift change. As the reason for that, increased hydrostatic pressure toward the ophthalmic vein might contribute to dilation of veins in the deep choroidal layer and greater choroidal blood volume. (Aviat Space Environ Med 2012; 83:1-6). We thus hypothesized that thickness would be increased at choroidal sites at some distance from the fovea, and that there are differences in the degree of the thickening among parts. The purpose of this study is to verify the degree of the thickening in different parts of the choroid.
The right eyes of nine healthy subjects (seven men, two women) were examined. Subfoveal choroidal thickness and 4 sites 2500 µm apart from the fovea; at the head side of the fovea, the nasal side, the temporal side and the foot side of the fovea, totally 5 sites of choroidal thickness were measured using spectral domain-optical coherence tomography in the sitting position, and after 15 and 30 min of 10° HDT.
Subfoveal, nasal, and temporal choroidal thicknesses were significantly increased with 15-min. The amount of change with 15-min was 17.7±6.6 µm at nasal, 15.4±3.6 µm at fovea, 23.6±6.3 µm at temporal, respectively (mean±S.E.M.). On the other hand, with 30-min HDT, all 5 sites choroidal thicknesses significantly increased. The amount of increased choroidal thickness change with 30-min HDT were 32.9±8.5 µm at fovea, 32.5±6.2 µm at nasal, 35.4±6.9 µm at temporal, 15.3±3.6 µm at the head side, and 14.1±3.2 µm at the foot side respectively.
Other choroidal sites including the fovea increased, and there were differences by choroidal sites. The amount of change of subfoveal, nasal, and temporal choroidal thickness were twice of that of the head side and the foot side.
This PDF is available to Subscribers Only