title: Acute variations in retinal vascular oxygen content in a rabbit model of retinal venous occlusion.
abstract: OBJECTIVE
  To study the variation in intravascular oxygen saturation (oximetry) during an acute retinal vein occlusion (RVO) using hyperspectral computed tomographic spectroscopy based oximetry measurements.
  
  
  METHODS
  Thirty rabbits were dilated and anesthetized for experiments. Baseline oximetry measurements were made using a custom-made hyperspectral computed tomographic imaging spectrometer coupled to a fundus camera. RVO were induced using argon green laser following an intravenous injection of Rose Bengal. RVO induction was confirmed by fluorescein angiography. Retinal oximetry measurements were repeated in arterial and venous branches one hour after RVO induction and up to 4 weeks afterwards. Comparison of retinal oximetry before and after vein occlusion was made using the Student T-test.
  
  
  RESULTS
  One hour after RVO induction, we observed statistically significant reductions in the intravascular oxygen saturation in temporal retinal arteries (85.1 ± 6.1% vs. 80.6 ± 6.6%; p<0.0001) and veins (71.4 ± 5.5% vs. 64.0 ± 4.7%; p<0.0001). This decrease was reversible in animals that spontaneously recannulated the vein occlusion. There were no statistically significant differences in oxygen saturation in the nasal control arteries and veins before and after temporal vein RVO induction.
  
  
  CONCLUSIONS
  We demonstrate, for the first time, acute changes in the intravascular oxygen content of retinal vessels 1 hour after RVO. These changes are reversible upon spontaneous recannulation of retinal vessels. This study demonstrates that hyperspectral computer tomographic spectroscopy based oximetry can detect physiological variations in intravascular retinal oxygen saturation. The study also provides the first qualitative and quantitative evidence of the variation in retinal vascular oxygen content directly attributable to an acute retinal vein occlusion.
authors.affiliation: Doheny Eye Institute, University of Southern California, Los Angeles California, United States of America.
authors.forename: Gilberto Raul Lopez
authors.initials: GR
authors.lastname: Jaime
authors.forename: Amir H
authors.initials: AH
authors.lastname: Kashani
authors.forename: Saloomeh
authors.initials: S
authors.lastname: Saati
authors.forename: Gabriel
authors.initials: G
authors.lastname: Martin
authors.forename: Gerald
authors.initials: G
authors.lastname: Chader
authors.forename: Mark S
authors.initials: MS
authors.lastname: Humayun
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D019793:Fluorescein; D005451:Fluorescein Angiography; D005456:Fluorescent Dyes; D010092:Oximetry / Q000379:methods; D010100:Oxygen / Q000378:metabolism*; D011817:Rabbits; D012160:Retina / Q000378:metabolism* / Q000473:pathology; D012161:Retinal Artery / Q000378:metabolism; D012169:Retinal Vein / Q000378:metabolism* / Q000473:pathology; D012170:Retinal Vein Occlusion / Q000378:metabolism* / Q000473:pathology; D012395:Rose Bengal
chemical_list: D005456:Fluorescent Dyes; D012395:Rose Bengal; D010100:Oxygen; D019793:Fluorescein