Photodynamic therapy for choriocapillaris using tin ethyl etiopurpurin (SnET2).
OBJECTIVE
To investigate the use of photodynamic therapy (PDT) using tin ethyl etiopurpurin (SnET2) for occluding the choriocapillaris in the eyes of pigmented rabbits.


METHODS
Following intravenous injection of SnET2 (0.5 and 1 mg/kg) or lipid emulsion alone, the fundus of pigmented rabbits (n = 21) was irradiated starting 15 to 45 minutes after photosensitizer injection using 664-nm light at a fluence of 300 mW/cm2 and light doses of 5 to 20 J/cm2. Funduscopy, fluorescein angiography, and light and electron microscopy were performed at 1, 14, and 28 days after PDT.


RESULTS
Following SnET2 and PDT, closure of the choriocapillaris was achieved with light doses as low as 5 J/cm2 (17 seconds) and a drug dose of 0.5 mg/kg of SnET2. Vascular occlusion was documented by fluorescein angiography and histology. Photodynamic damage was noted in the choriocapillary endothelial cells. Retinal pigment epithelial damage and outer retinal damage were also observed. No funduscopic, angiographic, or histologic findings were present in the eyes of pigmented control rabbits.


CONCLUSIONS
PDT with SnET2 was effective in this animal model, using low levels of activating light for the occlusion of the choriocapillaris. This has clinical implications for the treatment of choroidal neovascularization and could be a more selective therapy than thermal laser photocoagulation.
Peyman
G A
GA
Department of Ophthalmology LSU Eye Center, Louisiana State University Medical Center, New Orleans 70112-2234, USA.
Moshfeghi
D M
DM
Moshfeghi
A
A
Khoobehi
B
B
Doiron
D R
DR
Primbs
G B
GB
Crean
D H
DH
D000818:Animals; D002829:Choroid / Q000098:blood supply*; D004730:Endothelium, Vascular / Q000648:ultrastructure; D005451:Fluorescein Angiography; D005654:Fundus Oculi; D007275:Injections, Intravenous; D009389:Neovascularization, Pathologic / Q000188:drug therapy*; D010778:Photochemotherapy / Q000379:methods*; D011166:Porphyrins / Q000008:administration & dosage / Q000627:therapeutic use; D011817:Rabbits; D011838:Radiation-Sensitizing Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D012171:Retinal Vessels / Q000648:ultrastructure
D011166:Porphyrins; D011838:Radiation-Sensitizing Agents; C063166:tin etiopurpurin