The purpose of the study was to evaluate the choroidal thickness in patients with central serous chorioretinopathy, a disease attributed to increased choroidal vascular hyperpermeability. Patients with central serous chorioretinopathy underwent enhanced depth imaging spectral-domain optical coherence tomography, which was obtained by positioning a spectral-domain optical coherence tomography device close enough to the eye to acquire an inverted image. Seven sections, each comprising 100 averaged scans, were obtained within a 5 degrees x 30 degrees rectangle to encompass the macula. The subfoveal choroidal thickness was measured from the outer border of the retinal pigment epithelium to the inner scleral border. The mean age of subjects undergoing enhanced depth imaging spectral-domain optical coherence tomography was 59.3 years (standard deviation, 15.8 years). Seventeen of 19 patients (89.5%) were men, and 12 (63.2%) patients had bilateral clinical disease. The choroidal thickness measured in 28 eligible eyes of the 19 patients was 505 microm (standard deviation, 124 microm), which was significantly greater than the choroidal thickness in normal eyes (P < or = 0.001). Enhanced depth imaging spectral-domain optical coherence tomography demonstrated a very thick choroid in patients with central serous chorioretinopathy. This finding provides additional evidence that central serous chorioretinopathy may be caused by increased hydrostatic pressure in the choroid.