Abstract
Abstract: :
Purpose:To study the oxygen saturation (OS) levels in different areas of the posterior fundus of human eyes. Methods:Ten healthy volunteers of age differences smaller than two years were recruited and examined funduscopically. Afterwards, oxygen saturation (OS) levels of the retina were estimated using a spectral retinal imager (ASI Ltd, Migdal Ha'Emak, Israel). This spectral retinal imager consists of a fundus camera (Topcon TRC-50IA), a Sagnac interferometer with a charge-coupled device (CCD), and acquisition and analysis software modules that are running on a personal computer. The image acquisition process takes 6 seconds in which the fundus is illuminated by the white incandescent light of the fundus camera at the regular power settings. OS values in each pixel of the fundus image with a 35- degree view can then be estimated from the respective spectrum that is obtained by Fourier-transforming the interferometer signals. Each OS values is represented by a specific color, and each pixel of the fundus image is painted accordingly. This way, retinal OS maps of the examined healthy eyes were produced. In addition, in this study average OS values were calculated in three retinal regions: 1) Fovea with 2 disc diameter; 2) Macula with 4 disc diameter; and 3) Juxta papilla with 3 disc diameter. Results:At the three aforementioned sites, fovea, macula without fovea, and juxta-papillary, we have obtained oxygen saturation (OS) values of 59.2±6.2 %, 66.0±4.2 %, and 77.8±4.0 %, respectively. Correspondingly, the retinal OS maps showed relative low OS values in areas wider than the a-vascular fovea. Conclusion:The OS level of juxta-papillary area was the highest, while that of the fovea was the lowest in the posterior fundus. Contrary to abundant choroidal circulation in the fovea, the overlying retina may be under relative low oxygen level. As the retinal pigment epithelium may be efficient enough to block the effect of the choroid optically, so our results may indicate that the OS levels measured with our system represent oxygen saturation of the retina per se. ±