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M. Shahidi, J. Wanek, Y. Rawash, N. P. Blair, M. Mori; An Imaging Method for Quantitative Measurement of Retinal Tissue Oxygen Tension. Invest. Ophthalmol. Vis. Sci. 2009;50(13):1403.
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© ARVO (1962-2015); The Authors (2016-present)
Abnormalities in retinal oxygenation have been implicated in the development of many retinal diseases. Technologies that allow direct assessment of retinal oxygenation are needed to investigate the role of oxygen in the development of disease-related retinal pathologies. The purpose of the study is to report and validate a method based on optical section phosphorescence imaging that allowed mapping of oxygen tension (pO2) in the retinal tissue.
Our optical section phosphorescence lifetime imaging system was utilized to provide quantitative measurements of pO2 in the retinal tissue. A narrow laser line was projected at an angle on the retina after intravitreal injection of an oxygen-sensitive molecular probe and phosphorescence emission was imaged. Phosphorescence lifetime and pO2 were measured at each pixel on the image. Retinal pO2 maps were generated in 10 rat eyes while varying the fraction of inspired oxygen (FiO2). Average retinal pO2 profiles across the retinal depth were generated from pO2 maps. Maximum, minimum, and slope of the outer retina pO2 profiles, and mean of the inner retina pO2 were calculated.
Systemic arterial pO2 measurements varied according to FiO2 and were significantly different during FiO2 = 10%, 21%, and 50% (P < 0.001). Maximum pO2 obtained during FiO2 = 10%, 21%, and 50% were 38 + 15, 54 + 13, and 76 + 21 mm Hg, respectively (P = 0.009). The maximum pO2 was correlated with systemic arterial pO2 (r = 0.6; P = 0.01). The intrasubject maximum pO2 variabilities were 4, 6, and 6 mm Hg, during FiO2 = 10%, 21%, and 50%, respectively. The slope of the outer retina pO2 profile was negatively correlated with maximum pO2 (r = 0.7; P = 0.001). The difference between maximum and minimum outer retina pO2 obtained during FiO2 = 10%, 21%, and 50% were 13 + 7, 24 + 9, and 37 + 10 mm Hg, respectively, and were significantly different (P = 0.003). The mean inner retina pO2 was correlated with maximum pO2 (r = 0.8; P < 0.001).
A method was developed for mapping and quantitative measurement of oxygen tension in the retinal tissue that has potential to provide better understanding of retinal oxygenation in health and disease.
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