Corneal Endothelium after Infrared Laser Exposure. Evaluation of Techniques to Study Corneal Lesions

摘要

Specimens of corneal endothelium of adult rhesus monkeys were evaluated for alterations by one of three staining techniques. One cornea from each animal had been exposed to carbon dioxide laser radiation (at 10.6 micrometer, 100 msec, 65, 45, or 35 watts/sq. cm, spot diameter of 3.2 mm at the 1/e intensity points) and removed surgically two hours after exposure. The other eye of each of the 18 monkeys served as controls (they were not exposed to laser radiation). Six specimens, two at each exposure, were stained with trypan blue (TB); nine specimens, three at each exposure, were stained with tetrazolium salt medium (TNBT); and three specimens, one at each exposure, were stained with hematoxylin. Each control cornea was stained with the same as the matching specimen. All specimens were processed for histologic examination by embedding in Epon. The combined use of TB and TNBT staining procedures allows detection of subtle alterations of the corneal endothelium at irradiances as low as 35 watts/sq. cm of CO2 laser (10.6 micrometer) radiation for a 100 msec exposure. At irradiances from 35 to 65 watts/sq. cm, a progressive increase in the incidence of altered cellular viability and enzyme activity is induced. At these techniques, in combination, are applied, the response of the corneal endothelium to infrared laser radiation and its dose dependence can be described more accurately. (Author)