Epithelial damage in rabbit corneas exposed to CO2 laser radiation.
Corneal injury thresholds are determined for conditions not previously explored for CO2 laser radiation, including multiple-pulse exposures and a systematic investigation of the effect of beam diameter on single-pulse damage thresholds. Multiple-pulse exposures from pulse trains up to 999 pulses, having pulse repetition frequencies between 1 and 100 Hz and individual pulse durations between 10(-3) and 0.5 s, were explored. Damage thresholds are discussed in terms of an approximate critical temperature model, the damage integral model and other empirical correlations. Single-pulse exposures are accurately correlated by an empirical critical temperature model in which the critical temperatures have a weak dependence on exposure duration. However, certain aspects of the single-pulse damage data led us to propose a new thermal damage model that incorporates an endothermic phase transition as the damage mechanism. This physical model accurately correlates single-pulse damage for exposures between 10(-3) and approximately 10 s.
Bargeron
C B
CB
Milton S. Eisenhower Research Center, Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20707.
Deters
O J
OJ
Farrell
R A
RA
McCally
R L
RL
D000818:Animals; D065306:Corneal Injuries; D004848:Epithelium; D007834:Lasers / Q000009:adverse effects*; D011817:Rabbits