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AC Bourgeois, B Khoobehi; Choroidal Leukostasis Using Deeper Infrared Fluorescent Dye . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3292.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To introduce a dye that can be used to study choroidal leukostasis in an animal model. Methods: In order to isolate the choroid from the retina, retinal ischemia was induced in one eye in each of 12 rats. Retina ischemia was created by closing the central retinal veins and arteries with an IR laser at 810 nm (laser parameters: power 300 mW, exposure time 500 ms, and spot size 500 µm). Fourteen days after the laser procedure, in vivo staining of leukocytes was performed using the infrared dye perchlorate, which absorbs at 820 nm and fluoresces at 880 nm. The dye (0.1 ml at a concentration of 1 mg/ml) was perfused through the tail vein over 1 minute. Scanning laser ophthalmoscopy in infrared mode was used to look for static and dynamic leukocytes in the choroid of one eye of each rat and the retina and choroid in the other eye. Results: Immediately after dye injection, fluorescent leukocytes were visible in the circulation; however, there were no static leukocytes present. Twenty minutes after dye perfusion, a number of static leukocytes were visible in both the choroid and the retina; roughly 20 to 30 static fluorescent leukocytes were observed in choriocapillaries in the field of view at that time. The number increased with time and peaked approximately 2 hours after dye injection. Our observations showed the phenomenon to be a dynamic process, with leukocytes becoming static and returning to the circulation over time. We have not yet identified the types of leukocytes involved in this process. Conclusion: In the past, acridine orange has been used to study leukostasis in the retina. However, the infrared dye we used in these studies can also be used to study leukostasis in the choroidal vessels. The evaluation of choroidal leukostasis can be used to assess the involvement of choriocapillaries in different types of vascular disease such as diabetes and the formation of subretinal membranes in age-related macular degeneration.
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