Impact of short-term astigmatic defocus on human choroidal thickness

Purpose: To examine the changes in choroidal thickness (CT) of healthy adults following short-term exposure to with-the-rule (WTR) and against-the-rule (ATR) simple myopic astigmatic defocus, with CT changes associated with spherical myopic defocus and clear vision used as control conditions. Methods: The left eye of 13 young adults was exposed to spectacle induced +3 D X 180 WTR, +3 D X 90 ATR, +3 D spherical myopic defocus or clear vision for 60 minutes of TV viewing, over 4 randomly ordered visits, while their right eye was optimally corrected. Measures of CT, averaged across the central 5 mm macular region along the vertical and horizontal meridians, were obtained before and after the defocus period using optical coherence tomography during simultaneous exposure to the defocus stimulus. Results: CT did not change during the clear control visit (-1 ± 5 µm, p=0.38) and increased significantly in response to +3 D spherical myopic defocus (+6 ± 5 µm, p