Abstract
Ten rhesus monkeys were exposed to 30 psec pulses of a mode-locked Nd:YAG laser such that four eyes received only 532 nm radiation, 12 eyes received only 1064 nm radiation and four eyes received both 532 and 1064 nm radiation. Ocular damage thresholds for the unfocused beam were 8·7±4·8 μJ at 1064 nm and 18·2±8·3 μJ at 532 nm. In addition, 1064 nm exposures were made with retinal exposure diameters of 430, 630 and 725 μm. Threshold exposures were 1521±330 μJ, 1017±700 μJ and 1184±334 μJ respectively, corresponding to retinal radiant exposures of 1·6, 0·50 and 0·44 J/cm 2. Ultrastructural studies indicate that at 1064 nm, the damage mechanisms are independent of image size. Damage is postulated to result from shock waves produced by transient heating of melanin granules. At 532 nm, photochemical damage to the outer segment membranes is super-imposed upon photomechanical damage from shock waves.
Published Version
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