视网膜中的激光诱导气泡形成。
Laser induced bubble formation in the retina.
作者信息
Gerstman B S, Thompson C R, Jacques S L, Rogers M E
机构信息
Department of Physics, Florida International University, Miami 33199, USA.
出版信息
Lasers Surg Med. 1996;18(1):10-21. doi: 10.1002/(SICI)1096-9101(1996)18:1<10::AID-LSM2>3.0.CO;2-U.
BACKGROUND AND OBJECTIVE
The immediate thermodynamic effects of absorption of a laser pulse in the retina are theoretically studied to understand underlying physical damage mechanisms at threshold fluences. Damage is most likely to occur at threshold levels in the retinal pigment epithelium due to the strong absorption by the melanosomes.
METHODS
The retinal pigment epithelium is modeled as an aqueous environment with absorption occurring at small spherical sites with absorption coefficients representative of melanosomes. For laser pulse durations of less than 10(-6) seconds, heat conduction is negligible during energy deposition and the resulting large energy density in the melanosomes will cause vaporization of the medium immediately surrounding a melanosome.
RESULTS
We developed expressions for calculating the size of bubbles produced as a function of pulse characteristics and melanosome properties. We show that for pulse durations between 10(-6) and 10(-9) seconds, bubble formation will occur for laser fluences that are smaller than those required to cause Arrhenius-type thermal damage.
CONCLUSION
Bubble formation is likely to be the mechanism of threshold damage to the retina for laser pulses durations in the time regime between 10(-6) and 10(-9) seconds.
背景与目的
从理论上研究视网膜对激光脉冲吸收的即时热力学效应，以了解阈值能量密度下潜在的物理损伤机制。由于黑素体的强烈吸收，视网膜色素上皮在阈值水平时最有可能发生损伤。
方法
将视网膜色素上皮模拟为一种水环境，吸收发生在具有代表黑素体吸收系数的小球形部位。对于持续时间小于10⁻⁶秒的激光脉冲，在能量沉积过程中热传导可忽略不计，黑素体内产生的高能量密度会导致黑素体周围介质立即汽化。
结果
我们推导了根据脉冲特性和黑素体特性计算产生气泡大小的表达式。我们表明，对于持续时间在10⁻⁶到10⁻⁹秒之间的脉冲，导致气泡形成的激光能量密度低于引起阿累尼乌斯型热损伤所需的能量密度。
结论
对于持续时间在10⁻⁶到10⁻⁹秒之间的激光脉冲，气泡形成可能是视网膜阈值损伤的机制。
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