Analysis of visual pigment by fundus autofluorescence.
This study investigated changes of short-wavelength fundus autofluorescence (SW-AF) by retinal bleaching effects. All measurements were performed with the Heidelberg Retina Angiograph 2 (HRA 2). Initially, experimental imaging was done on a healthy eye after dark adaptation. Photopigment was bleached within the central 30 degrees of the fundus by HRA 2 excitation light. Then SW-AF imaging of this region was performed, and SW-AF of the surrounding, unbleached 25 degrees fundus region was subsequently studied by a wide-field lens. Next, another 30 degrees SW-AF image of the posterior pole was obtained after complete dark adaptation. Then an extra SW-AF examination was performed with 15 degrees temporal eccentricity, overlapping the original examination area. Finally, a successive image series was carried out on the dark-adapted eye to test for bleaching kinetics. The second and third experiments were also performed on eyes with macular dystrophies. Distinct regions of increased SW-AF were observed after strong illumination with the blue excitation light in all eyes studied. During light adaptation mean gray levels showed a saturation plateau after an initial steep increase. The resulting gray-value maps showed significant differences of pixel intensities between bleached and unbleached parts of the fundus. Two-dimensional density difference maps allowed analysis of visual pigment distribution and density in both healthy eyes and eyes with macular dystrophies. Our observations highlight the viability of objective, non-invasive evaluation of visual pigment in the healthy and diseased human retina by means of confocal fundus autofluorescence.
Theelen
T
T
Department of Ophthalmology, Radboud University Nijmegen Medical Centre, Philips van Leydenlaan 15, Nijmegen, The Netherlands. t.theelen@ohk.umcn.nl
Berendschot
T T J M
TT
Boon
C J F
CJ
Hoyng
C B
CB
Klevering
B J
BJ
D003623:Dark Adaptation / Q000502:physiology; D005451:Fluorescein Angiography; D006801:Humans; D008268:Macular Degeneration / Q000378:metabolism*; D009887:Ophthalmoscopy; D010775:Photic Stimulation / Q000379:methods; D038761:Photobleaching; D010786:Photoreceptor Cells / Q000378:metabolism; D012168:Retinal Pigments / Q000378:metabolism*
D012168:Retinal Pigments