Threshold power levels for NPe6 photodynamic therapy.
OBJECTIVE
To determine the threshold power levels for producing retinal and choroidal vascular occlusion using mono-L-aspartyl chlorin e6 (NPe6) photodynamic therapy; to evaluate its efficacy with longer intervals between photosensitizer injection and laser application; to determine the elapsed time between light application and appearance of angiographic changes.


METHODS
Pigmented and nonpigmented rabbits were injected intravenously with 2 mg/kg of NPe6 before laser irradiation of the retina-choroid. Group 1 was treated at increasing power levels; fluorescein angiograms were obtained at each fluence. Group 2 animals were exposed to laser irradiation at 5 minutes, and 1 and 3 hours postinjection to determine (by fluorescein angiography 24 hours post-treatment) if increasing the interval affected outcome. Group 3 animals underwent fluorescein angiography at 30 minutes, 1 hour, 2 hours, and 24 hours posttreatment to document the time between laser application and subsequent vessel closure.


RESULTS
Choroidal vessel occlusion was angiographically evident in all lesions at fluences of > or = 2.65 J/cm2 in pigmented rabbits and at > or = 0.88 J/cm2 in nonpigmented rabbits. Lesion diameter decreased as the time between injection and treatment increased. Vessel occlusion was documented at least 2 hours after treatment.


CONCLUSIONS
Choroidal vessel occlusion can occur at very low fluence.
Kazi
A A
AA
LSU Eye Center, Louisiana State University Health Services Center School of Medicine, New Orleans, 70112-2234, USA.
Peyman
G A
GA
Unal
M
M
Khoobehi
B
B
Yoneya
S
S
Mori
K
K
Moshfeghi
D
D
Moshfeghi
A A
AA
D000818:Animals; D002829:Choroid / Q000098:blood supply / Q000473:pathology; D020256:Choroidal Neovascularization / Q000188:drug therapy* / Q000473:pathology; D005451:Fluorescein Angiography; D007275:Injections, Intravenous; D007834:Lasers; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D011166:Porphyrins / Q000627:therapeutic use*; D011817:Rabbits; D015861:Retinal Neovascularization / Q000188:drug therapy / Q000473:pathology; D013997:Time Factors
D017319:Photosensitizing Agents; D011166:Porphyrins; C053434:Talaporfin