Abstract
Purpose: :
To compare the chorioretinal tissue damage after half dose of verteporfin, half laser energy or half laser time in photodynamic therapy (PDT) in pigment rabbits.
Methods: :
A total of 16 pigment rabbits were included in PDT study. The rabbits were grouped according to the usage of different half volume of drug, laser energy or laser time. In group 1 of 4 rabbit, full dose of verteporfin (4 mg/kg verteporfin) and 600 mW/cm2 irradiance of diode laser at 689 nm was applied on retina for 8 seconds. In group 2 of 4 rabbit, full dose of verteporfin and half laser energy (300 mW/cm2 ) irradiance of diode laser applied for 8 seconds. In group 3 of 4 rabbit, half dose of verteporfin (2 mg/kg verteporfin) and 600 mW/cm2 irradiance of diode laser was applied for 8 seconds. In group 4 of 4 rabbit, full dose of verteporfin and 600 mW/cm2 irradiance of diode laser was applied half time for 4 seconds. Six laser spots were applied in both eyes of every rabbit and 3 lesions were placed separately by optic disc and these lesions were graphically documented. The lesions of PDT in animals were examined 1 days, 7 days and 42 days by color fundus, fluorescein angiography (FA), histopathology and electronic microscopy (EM) analysis after treatments.
Results: :
The FA study of PDT in day 1 showed reduced laser energy may decrease the damage of retinal tissue either in the number and the area of occlusion. The FA images fade out in day 7 and 42. The histopathology and EM demonstrated the retinal tissue got nearly equal damage at group 1, 3, 4. However, group 2 with half laser energy showed less retinal damage in histological examination. The EM images also indicated the similar results.
Conclusions: :
Laser energy is the most important factors to influence the chorioretinal damage of PDT. Therefore, in treatment of the choroidal lesion such as CSC, reduce laser energy may reduce the collateral damage.
Keywords: photodynamic therapy • choroid: neovascularization • age-related macular degeneration