Measurement and Prediction of Thermal Injury in the Retina of the Rhesus Monkey

Abstract

The authors measured temperature rises with specially designed microthermocouples in over 60 retinae for various image sizes, wavelengths, and exposure durations. Measured temperatures varied with a standard error of 6 percent, and agreed well with a mathematical model for temperature-time response. Observed injury also compared favorably to that predicted by a rate process model for thermal injury. Suggested rate constants for the eye are A = 1.3 ×1099 1/s, and E = 150 000 cal/M. With these coefficients, predicted threshold injury agreed within a factor of two with experimentally determined injury from 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-8</sup> to 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> s. No difference in threshold temperatures was evident between either macular and paramacular exposures or between wavelengths of 488-647 nm. The model can be used to predict injury in the human eye by substituting absorption coefficients and thickness for the human PE and Ch in the thermal portion of the model.