Fluorescence properties of a hydrophilic sensitizer in pigmented rats, rabbits, and monkeys

BACKGROUND AND OBJECTIVE: To evaluate fluorescence properties of mono-L-asp artyl chlorin e6 (NPe6; Meija Seika Kaisha, Ltd., Tokyo, Japan) photodynami c therapy, which allows real-time simultaneous imaging of choroidal and ret inal vasculature during treatment without the addition of another dye. MATERIALS AND METHODS: Four pigmented rabbits, 4 pigmented rats, and 2 Afri can green monkeys were administered intravenous injections of the NPe6 dye. The animals were immediately placed in front of the scanning laser ophthal moscope and the fundus was viewed with the helium-neon Laser, The resulting fluorescence was viewed and recorded on super-VHS videotape. RESULTS: Fluorescence demonstrated clearly that NPe6 entered the retinal an d choroidal circulation within seconds of intravenous injection. The concen tration of NPe6 was diminished over a period of 1.5 hours in the monkey and 5 hours in the rat, as evidenced by considerable diminution of the intensi ty of fluorescence, CONCLUSION: NPe6 fluorescence allows evaluation of drug availability within the retinal and choroidal circulation and visualization of pathological le sions before commencement of photodynamic therapy.