22 May 1995 Laser-induced bubble formation in the retina
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Abstract
Bubble formation in the retinal pigment epithelium by submicrosecond laser pulses may be a source of laser induced retinal damage. Heat conduction away from absorbing melanin granules requires timescales on the order of microseconds. For pulses of shorter duration, all energy absorbed is effectively absorbed as a (delta) -function in time, and energy concentration may be high enough to cause vaporization of the surrounding medium. This occurs at lower fluences than required for thermal denaturation of a significant volume of cellular material. The adiabatic nature of the absorption and subsequent expansion is used to develop expressions for the calculation of maximum bubble size as a function of laser intensity and melanosome properties such as radius and absorption coefficients. We describe the analysis that went into the development of the bubble size expression and also present the results for representative calculations of maximum bubble radius. We find that our expression leads to a threshold for the formation of bubbles in the retinal pigment epithelium that is close to the ED50 experimentally measured for laser induced retinal damage.
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Bernard S. Gerstman, Bernard S. Gerstman, Charles R. Thompson, Charles R. Thompson, Steven L. Jacques, Steven L. Jacques, Mark E. Rogers, Mark E. Rogers, } "Laser-induced bubble formation in the retina", Proc. SPIE 2391, Laser-Tissue Interaction VI, (22 May 1995); doi: 10.1117/12.209929; https://doi.org/10.1117/12.209929
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