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S. Zhang, K. Wang, L. Wang; Preliminary Observation of the Biological Effect of Transpupillary Thermotherapy on Rabbit Retina and Choroid . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4892.
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© ARVO (1962-2015); The Authors (2016-present)
Objective To observe the biological effect of TTT on rabbit retina and choroid, and to provide clinical reference for rational application of TTT in treatment of choroidal neovascularization (CNV). Method TTT were performed on 16 eyes of 8-pigmented rabbits using the 810nm diode laser (IRIS Medical Oculight SLx) in different intensity (spot size, 1.2 mm; duration, 60 sec; power, 150, 200, 250, and 300 mW). Observations were made by optic microscope and transmission electron microscope to investigate the changes of figure and structure of retina and choroid at 1 hour and 1 month after TTT. Results Only mild changes of retinal pigment epithelium (RPE) can be found with the lowest irradiance (150mW); in addition, cellular denaturation, and stasis of the red blood cells in choroids also occurred for 200 mW laser. When the irradiance was 250 mW, the damage of outer part of sensory retina can be observed in the acute stage, and in 1 month after TTT, the rod/cone cell and the outer nuclear layer disappeared, and the fibrous proliferation can also be found in choroid. With the energy of laser increased to 300 mW, the total retina was damaged, and haemorrhage of choroids happened, even worse neovascularized endothelium was detected in some areas of choroid. Conclusion The biological effect of TTT on rabbits is in direct proportion to irradiance of laser, the RPE and the choroid nearby is the target of TTT. The appropriate parameter may be used successfully in treatment of CNV, whereas excessive intensity of TTT may induce the choroidal neovascularization, it should be avoided in the clinical therapy.
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