Photodynamic therapy for antifibrosis in a rabbit model of filtration surgery.
OBJECTIVE
The purpose of this pilot study was to investigate the use of photodynamic therapy (PDT) using tin ethyl etiopurpurin (SnET2) as an adjunctive antifibrotic therapy for filtering surgery in a rabbit model.


METHODS
The pharmacokinetics of SnET2 were established by intravenous (1 mg/kg) and subconjunctival (25, 50, or 75 micrograms) injections and compared with controls. Intravenous and subconjunctival SnET2 injections were given prior to posterior lip sclerectomies followed by postoperative laser irradiation (664 +/- 7 nm; 100 mW/cm2; 30 J/cm2). Antifibrotic efficacy was established by clinical response and histologic examination.


RESULTS
After subconjunctival injections, large areas of avascular conjunctiva were produced and filtering bleb survival was prolonged. No effect was found for intravenously administered photosensitizer followed by light irradiation.


CONCLUSIONS
PDT may be an alternative antifibrotic therapy for filtration surgery that does not use chemotherapeutic agents or ionizing radiation. Multiple parameters (light, drug dose, irradiation area) may be manipulated to improve predictability of the antifibrotic effect.
Hill
R A
RA
Department of Ophthalmology, Beckman Laser Institute and Medical Clinic, University of California, Irvine 92717, USA.
Crean
D H
DH
Doiron
D R
DR
McDonald
T J
TJ
Liaw
L H
LH
Ghosheh
F
F
Hamilton
A
A
Berns
M W
MW
D000818:Animals; D000867:Anterior Chamber / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D004195:Disease Models, Animal; D004333:Drug Administration Routes; D005355:Fibrosis / Q000188:drug therapy / Q000209:etiology / Q000378:metabolism; D018463:Filtering Surgery / Q000009:adverse effects*; D005500:Follow-Up Studies; D010778:Photochemotherapy / Q000379:methods*; D010865:Pilot Projects; D011166:Porphyrins / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use; D011183:Postoperative Complications / Q000188:drug therapy* / Q000209:etiology / Q000378:metabolism; D011817:Rabbits; D011838:Radiation-Sensitizing Agents / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use*; D016896:Treatment Outcome
D011166:Porphyrins; D011838:Radiation-Sensitizing Agents; C063166:tin etiopurpurin