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Jonathan W Kim, Patricia Chevez-Barrios; Rabbit model of ocular photodynamic therapy using an indirect ophthalmoscope delivery system.. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3668.
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© ARVO (1962-2015); The Authors (2016-present)
The goal of this project was to demonstrate the feasibility of coupling the indirect ophthalmoscope delivery system with the 690 nm wavelength laser used to activate Verteporfin.
A total of six pigmented rabbits were treated with the Indirect laser delivery system. The laser source was provided by the Lumenis Opal 690 nm laser unit, delivered through a 810nm Indirect ophthalmoscope headpiece and a hand-held 28D indirect lens (1.4 mm spot size). Four rabbits received Verteporfin at a dose of 0.43 mg/kg. Two rabbits did not receive Verteporfin and represented controls. The timing of laser treatment after Verteporfin infusion ranged between 16-95 minutes.
There were a total of 21 laser treatments performed in 6 right eyes of 6 rabbits. Laser power levels ranged between 45-190 mW and treatment duration ranged between 1-3 minutes. In the 4 rabbits that received Visudyne, controlled retinal burns were seen at 40 mW and higher power levels. In the 2 control rabbits that did not receive Verteporfin, thermal burns were confirmed with fundus photography at 75 mw but not at lower power levels. Histopathology showed no evidence of generalized ocular damage in the cornea or lens. In the treated areas, there was a chorioretinal scar with degeneration and gliosis of the sensory retina, proliferation and migration of the retinal pigment epithelium, and fibrosis in the choroid.
This pre-clinical study suggests Verteporfin can be activated in the rabbit eye with the indirect ophthalmoscope delivery system and the 690 nm laser unit. Photodynamic therapy was confirmed at 40 mW with a 3 minute duration, while photocoagulation was achieved at 75 mW with a 1 minute duration. There was no evidence of generalized ocular injury, and this laser system was able to create predictable retinal burns in a targeted area of the retina. Indirect PDT may represent a potential new modality to treat pediatric retinal diseases.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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