Heat effects on the retina
Heat effects on the retina
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DOI：
10.3928/1542-8877-20030301-07
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发表时间：
2003-03-01
影响因子：
--
通讯作者：
Humayun, MS
中科院分区：
文献类型：
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作者：
Piyathaisere, DV;Margalit, E;Humayun, MS
背景与目的：研究眼内电子加热器对视网膜的散热和功耗影响。确定对视网膜无害的热参数将有助于开发可植入眼内电子视网膜假体。材料和方法：在狗身上，五个不同的视网膜区域被一个定制的眼内加热器探头触摸（1.4 × 1.4 × 1.0 mm）持续1秒，同时加热器耗散0（对照）、10、20、50或100 mW。将加热器机械地保持在玻璃体腔中，同时耗散500mW持续2小时，同时监测眼内温度。连续4周进行眼底照相和视网膜电图检查，对侧眼重复上述操作。将狗杀死，摘除双眼，并提交组织学检查。结果：在使用协议1的实验中，50 mW或更高的加热器设置引起视网膜组织立即可见的变白。从组织学上看，这种损害只有在眼睛立即被摘除时才明显。永久性损坏是由100 mW或更高的加热器设置造成的。根据方案2，两组之间没有发现眼科、视网膜电图或组织学差异。玻璃体温度升高5degreesC，视网膜附近温度升高2degreesC，注意到。结论：眼睛的液体环境作为散热器，能够耗散大量的功率。远离视网膜定位的电子芯片可以以比定位在视网膜表面上的芯片高得多的功率运行。
BACKGROUND AND OBJECTIVE: To study the heat and power dissipation effect of an intraocular electronic heater on the retina. The determination of thermal parameters that are nonharmful to the retina will aid in the development of an implantable intraocular electronic retinal prosthesis.MATERIALS AND METHODS: In dogs, five different retinal areas were touched with a custom intraocular heater probe (1.4 x 1.4 x 1.0 mm) for 1 second while the heater dissipated 0 (control), 10, 20, 50, or 100 mW In a second protocol, the heater was mechanically held in the vitreous cavity while dissipating 500 mW for 2 hours while monitoring intraocular temperature. The animals were observed for 4 weeks with serial fundus photography and electroretinography, The procedure was then repeated in the fellow eye. The dogs were killed and both eyes were enucleated and submitted for histology.RESULTS: In experiments using protocol 1, heater settings of 50 mW or higher caused an immediate visible whitening of the retinal tissue. Histologically, this damage was evident only if the eyes were immediately enucleated. Permanent damage was caused by heater settings of 100 mW or higher. Under protocol 2, no ophthalmologic, electroretinography, or histologic differences were noted between the groups. Temperature increases of 5degreesC in the vitreous and 2degreesC near the retina were noted.CONCLUSIONS: The liquid environment of the eye acts as a heat sink that is capable of dissipating a significant amount of power. An electronic chip positioned away from the retina can run at considerably higher powers than a chip positioned on the retinal surface.