title: Lipofuscin-associated photo-oxidative stress during fundus autofluorescence imaging.
abstract: OBJECTIVE
  Current standards and guidelines aimed at preventing retinal phototoxicity during intentional exposures do not specifically evaluate the contribution of endogenous photosensitizers. However, certain retinal diseases are characterized by abnormal accumulations of potential photosensitizers such as lipofuscin bisretinoids in the retinal pigment epithelium (RPE). We sought to determine these contributions by a numerical assessment of in-vivo photo-oxidative stress during irradiation of RPE lipofuscin.
  
  
  METHODS
  Based on the literature, we calculated the retinal exposure levels, optical filtering of incident radiation by the ocular lens, media, photoreceptors, and RPE melanin, light absorption by lipofuscin, and photochemical effects in the RPE in two situations: exposure to short-wavelength (λ = 488 nm) fundus autofluorescence (SW-AF) excitation light and exposure to indirect (diffuse) sunlight.
  
  
  RESULTS
  In healthy persons at age 20, 40, and 60, respectively, the rate of oxygen photoconsumption by lipofuscin increases by 1.3, 1.7, and 2.4 fold during SW-AF-imaging as compared to diffuse sunlight. In patients with STGD1 below the age of 30, this rate was 3.3-fold higher compared to age-matched controls during either sunlight or SW-AF imaging.
  
  
  CONCLUSIONS
  Our results suggest that the RPE of patients with STGD1 is generally at increased risk of photo-oxidative stress, while exposure during SW-AF-imaging amplifies this risk. These theoretical results have not yet been verified with in-vivo data due to a lack of sufficiently sensitive in-vivo measurement techniques.
authors.affiliation: Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands.
authors.forename: Michel M
authors.initials: MM
authors.lastname: Teussink
authors.affiliation: Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands.
authors.forename: Stanley
authors.initials: S
authors.lastname: Lambertus
authors.affiliation: Department of Applied Physics, University of Twente, Enschede, the Netherlands.
authors.forename: Frits F
authors.initials: FF
authors.lastname: de Mul
authors.affiliation: School of Optometry and Vision Sciences, Cardiff University, Wales, United Kingdom.
authors.forename: Malgorzata B
authors.initials: MB
authors.lastname: Rozanowska
authors.affiliation: Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands.
authors.forename: Carel B
authors.initials: CB
authors.lastname: Hoyng
authors.affiliation: Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands.
authors.forename: B Jeroen
authors.initials: BJ
authors.lastname: Klevering
authors.affiliation: Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands.
authors.forename: Thomas
authors.initials: T
authors.lastname: Theelen
mesh_terms: D000328:Adult; D005260:Female; D005451:Fluorescein Angiography / Q000009:adverse effects; D005654:Fundus Oculi; D006801:Humans; D008062:Lipofuscin / Q000378:metabolism*; D008268:Macular Degeneration / Q000151:congenital* / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D008297:Male; D008543:Melanins / Q000378:metabolism; D008875:Middle Aged; D061848:Optical Imaging / Q000009:adverse effects*; D018384:Oxidative Stress / Q000528:radiation effects; D055668:Photochemical Processes; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects*; D017319:Photosensitizing Agents / Q000378:metabolism*; D055213:Retinal Pigment Epithelium / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects*; D000080362:Stargardt Disease; D013472:Sunlight; D041623:Tomography, Optical Coherence / Q000009:adverse effects
chemical_list: D008062:Lipofuscin; D008543:Melanins; D017319:Photosensitizing Agents