Photodynamic therapy on ocular neovascularization

The efficacy of photodynamic therapy using porphymer sodium (PF) and newly-developed chlorin derivative (ATX-S10) for occlusion of corneal new vessels has been evaluated experimentally. Twenty-six albino rabbits were treated with an intravenous injection of 2mg/kg of PF, followed by argon green laser (514nm) irradiation to the corneal new vessels with three varieties of energy at 24, 48, 72 and 96 hours after the injection, respectively. In another group of 4 rabbits, diode laser (672nm) was irradiated with the energy from 43J/cm2 to 323J/cm2 at 4 and 6 hours after the administration of 12mg/kg of ATX-S10, respectively. The closure of corneal new vesseles was confirmed by slit-lamp examination, fluorescein angiography and light microscopic study. With PF, irradiation with exposure energy of 19.1J/cm2 during 24 and 72 hours after the administration was estimated to be suitable for the treatment, because new vesseles were closed with a mild damage of the surrounding normal tissue such as the iris. Exposure energy more than 38.2J/cm2 was thought to be excess since surrounding normal tissue was heavily damaged. With ATX-S10, selective closure of corneal new vessels were obtained by irradiation with exposure energy of 86.1/cm2 and 258J/cm2 at 4 and 6 hours after the administration, respectively. In control groups which received laser irradiation without photosensitizer administration, new vessels were not closed. These results suggests PF and ATX-S10 used here are new therapeutic agents for the treatment of corneal neovascularization. Especially, ATX-S10 is a promising new photosensitizer since it has more rapid elimination from the body and less skin phototoxicity than PF.