Abstract
Abstract: :
Purpose: A scanning laser ophthalmoscope (Hamamatsu Photonics) for photodynamic therapy (PDT) applied to choroidal neovascularization (CNV) in primates was evaluated for its ability to occlude the choriocapillaris in selected regions of the retina. Methods: The device contains lasers at 785 nm for fundus observation and at 670 nm for PDT (the absorption peak of the photosensitizer ATX-S10(Na), Photochemical/Allergan). Laser light is scanned horizontally with a frequency of 15.75 kHz and vertically with 60 Hz, and the number of scanning lines is 525. The observation angle is 30 degrees diagonally. The dimension of the laser spot for PDT is 50 micrometers horizontally and 70 micrometers vertically on the surface of the retina. The peak power is 10 mW, which avoids thermal effects. Using the scanning laser device, the retina was irradiated in any shape according to the area pre-determined on a touch-screen monitor prior to PDT. Irradiation was terminated automatically when the set dose was achieved. The occlusion of the choriocapillaris after PDT was documented by fluorescein and indocyanine green angiographies and histology. The animals were treated in accordance with the resolution on the use of animals in research indicated by the ARVO, and all experimental procedures were performed under general anesthesia. Results: The shape of the area of PDT treatment was easily defined, and occlusion of the choriocapillaris was achieved in the exact area set for treatment, using 5 J/cm2 or more of radiance and an 8 mg/kg dose of ATX-S10(Na). Conclusion: Since the shape of CNV lesions are irregular, this device would be useful for limiting irradiation to CNV and sparing the surrounding retina undesirable damage. Our previous studies suggested that undesirable damage to the retina and choroid would induce not only functional disturbances but also increase recurrence of CNV. The present device, therefore, should allow for more effective PDT than the slit-lamp systems currently used.
Keywords: 516 photodynamic therapy • 308 age-related macular degeneration • 432 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)