Localization of rose bengal, aluminum phthalocyanine tetrasulfonate, and chlorin e6 in the rabbit eye.
OBJECTIVE
The localization and site of action of photosensitizers in the eye may be important for photodynamic therapy for fundus disorders but remain poorly understood for most agents. We investigated the intraocular localization of xanthene, phthalocyanine, and chlorin photosensitizers by using fluorescence microscopy and digital fundus fluorescence angiography.


METHODS
Rose bengal (40 mg/kg), aluminum phthalocyanine tetrasulfonate (CASPc) (5 mg/kg), or chlorin e6 (2 mg/kg) was intravenously administered to albino rabbits. The eyes were enucleated and examined by means of fluorescence microscopy 5, 20, 60, and 120 minutes and 24 hours after dye injection. In vivo digital fundus fluorescence angiography with use of rose bengal (2-4 mg/kg), CASPc (2 mg/kg), and chlorin e6 (2 mg/kg) was performed.


RESULTS
For all agents studied pathologically, there was moderate fluorescence from the choroid and retinal pigment epithelium 5 minutes after dye injection. Mild fluorescence detected from the photoreceptor outer segments at 5 minutes was increased at 20 minutes. Angiographic studies with use of rose bengal, CASPc, and chlorin e6 revealed differences in the pattern and rate of photosensitizer accumulation.


CONCLUSIONS
Rose bengal, CASPc, and chlorin e6 accumulate rapidly in the choroid and retinal pigment epithelium and less rapidly in the outer retina. Differences in ocular localization of these photosensitizers were demonstrated. The significance of these findings for potential photodynamic therapy with these agents requires further investigation.
Haimovici
Robert
R
Laser Research Laboratory, Retina Service, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, USA.
Ciulla
Thomas A
TA
Miller
Joan W
JW
Hasan
Tayyaba
T
Flotte
Thomas J
TJ
Kenney
Alice G
AG
Schomacker
Kevin T
KT
Gragoudas
Evangelos S
ES
D000818:Animals; D002735:Chlorophyllides; D005123:Eye / Q000378:metabolism*; D005451:Fluorescein Angiography; D007211:Indoles / Q000493:pharmacokinetics*; D008856:Microscopy, Fluorescence; D009942:Organometallic Compounds / Q000493:pharmacokinetics*; D017319:Photosensitizing Agents / Q000493:pharmacokinetics*; D011166:Porphyrins / Q000493:pharmacokinetics*; D011817:Rabbits; D012395:Rose Bengal / Q000493:pharmacokinetics*; D014018:Tissue Distribution
D002735:Chlorophyllides; D007211:Indoles; D009942:Organometallic Compounds; D017319:Photosensitizing Agents; D011166:Porphyrins; C048577:aluminum tetrasulfophthalocyanine; D012395:Rose Bengal; C062985:phytochlorin