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Proceedings Paper

Theoretical investigation of thermal retinal response to photodynamic therapy or choroidal neovascularization
Author(s): Hongxia Chen; Ying Gu; Gang Cheng; Zaifu Yang; Fan-guang Liu; Li Zhang; Haixia Qiu
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Paper Abstract

To study the risk of thermal injury in photodynamic therapy for choroidal neovascularization by calculating the retinal temperature of rabbits, a mathematical model for laser induced thermal effect on retina was developed. Homogeneous layer retinal models of different pigmented rabbits were presented to analyze the light distribution. The finite element method realized by Matlab software was used to solve classical bio-heat transfer model - Pennis equation, in which heat loss due to choroidal blood flow was considered. The retinal temperature was calculated with different laser parameters, including different wavelengths (532nm, 578nm and 690nm), power density (200~1600 mW/cm2), spot diameter (1mm, 2mm and 3mm) and different pigmented eye fundi. The prediction results showed the retinal temperature increased first, then reached maximum in a few seconds and kept constant during laser irradiation. Once laser exposure ended, the temperature decreased quickly to normal. With the increase of laser power density and spot size, the retinal temperature raised too. The temperature reduced exponentially with the distance from laser spot increased. The maximum temperature of non-pigmented rabbits was lower than that of pigmented rabbits. The temperature induced by 578nm laser irradiation was highest, the next was by 532nm laser and the lowest was by 690nm laser. For current parameters used to treat choroidal neovascularization (690nm, 600mW, 2mm, 83sec), the maximum retinal temperature calculated was less than 45 °C, which indicating no thermal damage induced.

Paper Details

Date Published: 8 January 2008
PDF: 7 pages
Proc. SPIE 6826, Optics in Health Care and Biomedical Optics III, 68261O (8 January 2008); doi: 10.1117/12.756110
Show Author Affiliations
Hongxia Chen, Chinese PLA General Hospital (China)
Ying Gu, Chinese PLA General Hospital (China)
Gang Cheng, Beijing Institute of Technology (China)
Zaifu Yang, Beijing Institute of Radiation Medicine (China)
Fan-guang Liu, Chinese PLA General Hospital (China)
Li Zhang, Chinese PLA General Hospital (China)
Haixia Qiu, Chinese PLA General Hospital (China)

Published in SPIE Proceedings Vol. 6826:
Optics in Health Care and Biomedical Optics III
Xingde Li; Qingming Luo; Ying Gu M.D., Editor(s)

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