[Detection of retinal vascular endothelial damage by fluorescein isothiocyanate-labelled platelet]

Fluorescein isothiocyanate (FITC)-labelled platelets were prepared in Sprague Dawley rats, and brought back into the rat through their femoral veins. Their ability to detect the photocoagulation-induced damage in the occluded retinal vessels was examined by epifluorescence microscopy in whole mount retinal specimens and cryostat specimens. The photocoagulation effects on the major retinal vessels by yellow dye (577 nm) and orange red (600 nm) laser, with parameters of 100 mu, 0.05 sec, 70 m W and 3 exposures were compared. The occluded vessels showed extensive accumulation of labelled platelets in the specimens. The portions photocoagulated by the yellow laser also showed accumulation, but not those by the orange red laser. This difference was considered to be due to the difference of hemoglobin absorption at each wavelength.