Abstract
Abstract: :
Purpose: To evaluate the photodynamic treatment (PDT) potential of a new hydrosoluble photosensitizer (WST11, Negma). Methods: 136 pigmented rabbits were used. WST11 and verteporfin PDT effects were investigated for occlusive and non–occlusive parameters. Treated rabbit eyes were followed by indirect ophthalmoscopy, fluorescein angiography (FA) and histology at various intervals after PDT. Results: WST11 PDT using a fluence of 50J/cm2, 5mg/kg drug dose and DLI of 1 minute induced total choroidal occlusion associated with structural lesions of the overlying RPE and retina in 100% of the treated eyes. Weaker, non–occlusive PDT parameters (25J/cm2, 5mg/kg and DLI 10 minutes) did not induce choriocapillaries occlusion nor retinal lesions. Verteporfin PDT using 12mg/m2 drug dose, fluence 100 J/cm2 and DLI 5 minutes induced occlusive events in 89% of the eyes and histology damage of the overlying retina and RPE layer. Weaker non–occlusive verteporfin PDT parameters did not induce any choriocapillaries occlusion on FA. However in these eyes, definite structural damage of the retina and choroid tissues were observed on histology. Similar to verteporfin, WST11 PDT induces transient occlusion of the choriocapillaries observed up to one week after treatment. WST11 PDT parameters not inducing vessel occlusion do not cause RPE or retina structural damage. Conclusions: Despite its capacity to induce vessel obstruction, WST11 PDT does not cause damage to the RPE and overlying retina when no occlusion of the choriocapillaries takes place. The possibility to use WST11 PDT for the treatment of CNV in age–related macular degeneration remains to be further investigated.
Keywords: photodynamic therapy • drug toxicity/drug effects • choroid