Comparision of the Effects of Transpupillary Thermotherapy(TTT) of Pigmented and Albino Rabbit Retina

ABSTRACT

PURPOSE: We compared the clinicopathologic effects of TTT between pigmented and albino rabbits. METHODS: TTT was delivered using infrared diode laser at 810 nm(Iris Medical Instrument, Mountain Veiw, CA, USA) and applied with spot size of 3 mm, duration of 60 seconds. At 1 week and 4 weeks after TTT, fundus photographs and simultaneous FAG/ICG angiogram were taken with SLO(Scanning Laser Ophthalmolscopy, Rodenstock, Munish, Germany). Light and electron microscopic examination were performed. RESULTS: In pigmented rabbits, visible funduscopic change was visible even with minimal power setting(100 mW). Obliteration of choroidal vessels was observed on ICG angiogram. In microscopic examination, entire layers of neural retina, retinal pigment epithelial cells, and deep choroid were severely damaged at the center of treated fields. Whereas, in albino rabbits fundus changes were not observed at any power setting. However, focal thrombosis at margin of lesion was identified on ICG angiogram after power of 300 mW. In microscopic examination, tissue damage was developed up to 600 mW and the lesion extended into the superficial choroid posteriorly and outer neural retina anterioly. CONCLUSIONS: The effect of TTT was increased with fundus pigmentation. Clinically we should adjust TTT power setting according to the amount of melanin pigmentation in the fundus.