Measurement of Choroidal Thickness in Normal Eyes Using 3D OCT-1000 Spectral Domain Optical Coherence Tomography

The choroid is the connective tissue-containing vascular layer between the retina and the sclera that provides oxy-gen and nourishment to the outer retina. It is associated with the pathophysiology of many diseases affecting the retina, such as age-related macular degeneration, polyp-oidal choroidal vasculopathy, central serous chorioreti-nopathy, and high myopia-related chorioretinal atrophies [1]. Because choroidal change has a major role in the development and progression of these diseases, choroidal thickness, which reflects choroidal change, provides useful information to clinicians. Adequate measurement of choroidal thickness using spectral domain optical coherence tomography (SD-OCT) is possible by introduction of an enhanced depth imaging technique and by averaging several B-scan signals from the same position [2,3]. Using a long-wavelength light source is another approach to visualize the posterior cho-roid and sclera [1,4]. Recent studies in a healthy population report a range of choroidal thickness from 270 to 350 μm. A negative correlation between choroidal thickness and age was previously reported [1-3,5]. Choroidal thinning is prominent in highly myopic eyes, and refractive error af-fects choroidal thickness [6]. Previous studies of normal choroidal thickness profile