Activated rate processes and a specific biochemical mechanism for explaining delayed laser induced thermal damage to the retina

Laser induced thermal damage to the retina is investigated. The one step Arrhenius type thermal damage integral of Henriques is analyzed for its strengths and weaknesses. The zero-order activated rate process is shown to well represent the data for pulse durations greater than 10 mu s. A zero-order biochemical damage mechanism involving free radical formation and thermal disruption of the melanosome's protein coat is proposed as the initial molecular process that leads to cellular damage which appears after a delay. Data are presented that show the photoactivation of melanin granule oxidative reactivity. This in vitro data is evidence for an important step in our hypothesized damage pathway. (C) 1999 Society of Photo-Optical Instrumentation Engineers. [S1083-3668(99)00403-7].