Vascular targeting in photodynamic occlusion of subretinal vessels.
OBJECTIVE
To evaluate the potential of photodynamic therapy (PDT) using benzoporphyrin derivative (BPD) for occlusion of subretinal neovascular membranes, the authors studied efficiency and collateral damage of PDT-induced photothrombosis in the rabbit choriocapillary layer.


METHODS
Benzoporphyrin derivative, a new photosensitizer, currently in clinical trials for tumor therapy, was used. Low-density lipoprotein served as a carrier to enhance selective targeting of vascular endothelial cells.


RESULTS
Complete choriocapillary occlusion was achieved at a BPD dose of 2 mg/kg and a radiant exposure as low as 10 J/cm2. When PDT was performed 3 hours after BPD application, damage to the neural retina was minimal. Only inner photoreceptor segments showed mitochondrial swelling probably secondary to choroidal ischemia. Bruch's membrane remained intact. Retinal pigment epithelium was invariably damaged as seen with other photosensitizers.


CONCLUSIONS
Compared with photocoagulation BPD-PDT allows endothelial-bound intraluminal photothrombosis, sparing important structures such as neural retina and Bruch's membrane. It may thus provide a more selective treatment of juxtafoveal and subfoveal neovascular membranes.
Schmidt-Erfurth
U
U
Wellman Laboratories of Photomedicine, Massachusetts General Hospital, Boston.
Hasan
T
T
Gragoudas
E
E
Michaud
N
N
Flotte
T J
TJ
Birngruber
R
R
D000818:Animals; D016570:Bruch Membrane / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects; D002829:Choroid / Q000098:blood supply; D004337:Drug Carriers; D004730:Endothelium, Vascular / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects; D008077:Lipoproteins, LDL / Q000627:therapeutic use; D010778:Photochemotherapy / Q000379:methods; D010786:Photoreceptor Cells / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects; D010857:Pigment Epithelium of Eye / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects; D011166:Porphyrins / Q000008:administration & dosage / Q000627:therapeutic use*; D011817:Rabbits; D011838:Radiation-Sensitizing Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D015861:Retinal Neovascularization / Q000188:drug therapy* / Q000473:pathology; D012171:Retinal Vessels / Q000187:drug effects* / Q000473:pathology / Q000528:radiation effects
D004337:Drug Carriers; D008077:Lipoproteins, LDL; D011166:Porphyrins; D011838:Radiation-Sensitizing Agents; C504224:benzoporphyrin D