Abstract
Abstract: :
Purpose: To investigate oxygen saturation (OS) levels in the fundus responding either oxygen or carbon dioxide inhalant stress. Methods: Ten eyes of 10 normal subjects from 24 to 45 years of age were studied. Besides fundus examination, visual acuity, refractive error, the measurement of retinal oxygen saturation, and retinal flow (Scanning Laser Doppler Flowmetry, SLDF) were performed in all subjects. We used Retinal Cube system (Applied Spectral Imaging Ltd, Israel) called retinal oxymeter that calculates the OS by two dimension non–invasively (Yoneya et al, 2002). This system allows the measurement of a spectrum at every pixel and we measured the points on the temporal–superior, temporal–inferior, and macula lesions. The mean retinal flow of the temporal juxtapapillary retina was measured and calculated using SLDF perfusion analysis (Michelson’s program). The subjects were breathing 100% oxygen gas and a comination gas of 16% O2, 5% CO2 and 79% nitrogen. Before and after breathing gases, the OS and retinal flow were measured. Results: The mean retinal flow of the temporal juxtapapillary retina was significantly decreased in eyes with pure oxigen. The decrease rate of the mean flow from starting level was about –40%. The mean retinal flow was significantly increased in the eyes with inspired 5% CO2. The increase rate of the mean flow from starting level was about 15%. There was no significant change in the OS levels of the temporal retina and macula during both O2 induced hypoperfusion and CO2 induced hyperperfusion. Conclusion: This result may be reflected by the homeostatic mechanisms of the retina.