title: Quantitative evaluation of retinal response to laser photocoagulation using dual-wavelength fundus autofluorescence imaging in a small animal model.
abstract: OBJECTIVE
  To demonstrate the usefulness of dual-wavelength fundus autofluorescence (FAF) imaging for noninvasive, quantitative monitoring of dynamic changes associated with healing of retinal photocoagulation lesions in a small animal model.
  
  
  METHODS
  Brown Norway rats, exhibiting substantial age-dependent lipofuscin autofluorescence, were used to characterize the kinetics of FAF recovery after retinal photocoagulation. An argon laser with a beam diameter of 100 μm, exposure duration of 0.1 seconds, and a range of laser powers (8-22 mW) were used to create subthreshold, threshold, and suprathreshold lesions. A modified retinal angiograph was used to obtain dual-wavelength FAF images at 488 and 514 nm to quantify and monitor changes in retinal fluorescence up to 6 months.
  
  
  RESULTS
  Compared to white light funduscopy, the FAF images exhibited heightened definition and clarity of lesion boundaries immediately after laser exposure. No significant reduction in FAF was measured at or below laser powers of 8 mW. Furthermore, a linear, dose-dependent decrease in FAF (R(2) = 0.9605) was observed immediately after laser exposures of 13 to 22 mW. Complete recovery of baseline FAF was observed for 13.5 and 16 mW exposures at 3 weeks and 4 months, respectively. However, retinal damage was still evident at 6 months after suprathreshold exposure induced using 22 mW laser power.
  
  
  CONCLUSIONS
  The accumulation of lipofuscin in the aged Brown Norway rat makes it a suitable small animal model for the characterization of laser-induced injury in the retina based on FAF. Dual-wavelength FAF measurements provide a sensitive, quantitative, noninvasive means of monitoring recovery of laser-induced retinal injury.
authors.affiliation: Center for Biomedical Engineering, University of Texas Medical Branch, Galveston, Texas 77555-1106, USA.
authors.forename: Adam
authors.initials: A
authors.lastname: Boretsky
authors.forename: Massoud
authors.initials: M
authors.lastname: Motamedi
authors.forename: Brent
authors.initials: B
authors.lastname: Bell
authors.forename: Frederik
authors.initials: F
authors.lastname: van Kuijk
mesh_terms: D000818:Animals; D005451:Fluorescein Angiography; D017075:Laser Coagulation / Q000009:adverse effects*; D054020:Lasers, Gas / Q000009:adverse effects; D008062:Lipofuscin / Q000378:metabolism; D023421:Models, Animal; D009887:Ophthalmoscopy; D051381:Rats; D011914:Rats, Inbred BN; D012160:Retina / Q000293:injuries* / Q000378:metabolism; D055213:Retinal Pigment Epithelium / Q000378:metabolism*; D014945:Wound Healing / Q000502:physiology*
chemical_list: D008062:Lipofuscin