title: Quantitative spatial and temporal analysis of fluorescein angiography dynamics in the eye.
abstract: OBJECTIVE
  We describe a novel approach to analyze fluorescein angiography to investigate fluorescein flow dynamics in the rat posterior retina as well as identify abnormal areas following laser photocoagulation.
  
  
  METHODS
  Experiments were undertaken in adult Long Evans rats. Using a rodent retinal camera, videos were acquired at 30 frames per second for 30 seconds following intravenous introduction of sodium fluorescein in a group of control animals (n = 14). Videos were image registered and analyzed using principle components analysis across all pixels in the field. This returns fluorescence intensity profiles from which, the half-rise (time to 50% brightness), half-fall (time for 50% decay) back to an offset (plateau level of fluorescence). We applied this analysis to video fluorescein angiography data collected 30 minutes following laser photocoagulation in a separate group of rats (n = 7).
  
  
  RESULTS
  Pixel-by-pixel analysis of video angiography clearly delineates differences in the temporal profiles of arteries, veins and capillaries in the posterior retina. We find no difference in half-rise, half-fall or offset amongst the four quadrants (inferior, nasal, superior, temporal). We also found little difference with eccentricity. By expressing the parameters at each pixel as a function of the number of standard deviation from the average of the entire field, we could clearly identify the spatial extent of the laser injury.
  
  
  CONCLUSIONS
  This simple registration and analysis provides a way to monitor the size of vascular injury, to highlight areas of subtle vascular leakage and to quantify vascular dynamics not possible using current fluorescein angiography approaches. This can be applied in both laboratory and clinical settings for in vivo dynamic fluorescent imaging of vasculature.
authors.affiliation: Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Flora
authors.initials: F
authors.lastname: Hui
authors.affiliation: Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Christine T O
authors.initials: CT
authors.lastname: Nguyen
authors.affiliation: Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Phillip A
authors.initials: PA
authors.lastname: Bedggood
authors.affiliation: Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Zheng
authors.initials: Z
authors.lastname: He
authors.affiliation: Neusentis, Pfizer Research and Development, Grant Park Science Park, Cambridge, United Kingdom.
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Fish
authors.affiliation: Neusentis, Pfizer Research and Development, Grant Park Science Park, Cambridge, United Kingdom.
authors.forename: Rachel
authors.initials: R
authors.lastname: Gurrell
authors.affiliation: Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Algis J
authors.initials: AJ
authors.lastname: Vingrys
authors.affiliation: Department of Optometry and Vision Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Bang V
authors.initials: BV
authors.lastname: Bui
mesh_terms: D000818:Animals; D001794:Blood Pressure; D004195:Disease Models, Animal; D005451:Fluorescein Angiography / Q000379:methods; D007834:Lasers / Q000009:adverse effects; D051381:Rats; D012164:Retinal Diseases / Q000175:diagnosis / Q000209:etiology / Q000473:pathology; D012171:Retinal Vessels / Q000473:pathology / Q000528:radiation effects