title: In vivo ocular fluorophotometry: delivery of fluoresceinated dextrans via transscleral diffusion in rabbits.
abstract: OBJECTIVE
  To evaluate the transscleral delivery of fluoresceinated dextrans (FITC-D) with molecular mass up to 70 kDa to the rabbit posterior segment using sub-Tenon injections.
  
  
  METHODS
  Eighteen NZW rabbits received a unilateral 200-μL injection of 2 mg/mL sodium fluorescein (NaF), 25 mg/mL 40-kDa FITC-D, or 25 mg/mL 70-kDa FITC-D, with (n = 9) or without (n = 9) immediate euthanatization. In live animals, fluorescence was measured in the retina/choroid and mid-vitreous by fluorophotometry, immediately after injection and after 4, 24, 48, and 72 hours. Euthanatized animals were examined hourly through 5 or 6 hours.
  
  
  RESULTS
  In live animals, the average peak NaF concentration in the retina/choroid was 310.2 ng/mL, measured 3 hours after injection. Average 40- and 70-kDa FITC-D concentrations in the retina/choroid peaked at 5409.6 and 2375.6 ng/mL, respectively, 24 hours after injection. Fluorescence returned to baseline levels 6 hours after NaF injection, and 48 and 72 hours after 40- and 70-kDa FITC-D injections, respectively. Rabbits that received NaF followed by euthanatization exhibited a continuous increase in retina/choroid and mid-vitreous fluorescence, beginning 1 hour after injection, whereas FITC-D-injected eyes did not show elevated retina/choroid or mid-vitreous fluorescence through 6 hours.
  
  
  CONCLUSIONS
  FITC-D weighing up to 70-kDa, as well as NaF, reached the posterior retina/choroid after sub-Tenon injections in live rabbits. NaF and 40-kDa FITC-D reached higher peak concentrations and were cleared from the eye more rapidly than was 70-kDa FITC-D. There was minimal penetration of NaF and FITC-D into the mid-vitreous in the in vivo experiments.
authors.affiliation: Department of Ophthalmology, Emory University, Atlanta, Georgia 30322, USA.
authors.forename: Damian E
authors.initials: DE
authors.lastname: Berezovsky
authors.forename: Samirkumar R
authors.initials: SR
authors.lastname: Patel
authors.forename: Bernard E
authors.initials: BE
authors.lastname: McCarey
authors.forename: Henry F
authors.initials: HF
authors.lastname: Edelhauser
mesh_terms: D000818:Animals; D002829:Choroid / Q000378:metabolism*; D003911:Dextrans / Q000493:pharmacokinetics*; D004058:Diffusion; D019793:Fluorescein / Q000493:pharmacokinetics*; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D015590:Fluorophotometry; D056965:Injections, Intraocular; D011817:Rabbits; D012160:Retina / Q000378:metabolism*; D012590:Sclera / Q000378:metabolism*; D014018:Tissue Distribution; D014822:Vitreous Body / Q000378:metabolism*
chemical_list: D003911:Dextrans; C015219:fluorescein isothiocyanate dextran; D016650:Fluorescein-5-isothiocyanate; D019793:Fluorescein