STUDIES ON THE CHICKEN EYE PROPERTIES EXPOSED TO ARGON-LASER BY DIELECTRIC METHODS

Argon Laser is commonly used now as a powerful tool in the human eye operations. On the other hand, the exposure of the eye to laser, in the visible range, may cause many alterations in the retinal structure. The aim of the present work is to study the structural variations in the eye caused by argon laser exposure, of the same intensity and duration as that used in medical treatments and at different temperatures of 10, 20, and 30-degrees-C, by dielectric measurements. These measurements were carried out immediately after laser exposure and after a certain period (1 - 5 days) needed for the recovery processes. The results of the experiments showed that the impedance components (Z(R) and Z(l)) and the dielectric loss (is-an-element-of{''}) changed with temperature and after eye exposure to 1mW/cm2 argon laser of duration 0.12 sec. The dielectric loss, is-an-element-of{''}, increased immediately after laser exposure and then decreased during the recovery periods indicating a repairing process after laser treatments in the fourth or fifth day which is greatly significant at a temperature of 10-degrees-C. The exact reactive mechanism of laser effects on the eye is still not really understood. These effects may be due to vasodillation of blood vessels of the retina which is accompanied by an increase in blood capillary permeability. This increase in permeability permits larger serum proteins to inter the cells, shifting the osmotic pressure at the capillary wall such that cell swelling takes place due to water entrance. The repairing processes occurred due to that some intracellular substances are released and gradually diffused out of the cells and this would explain the latent period of several days. Based on the results of the present work. we may conclude that, in order to decrease the damage/repair ratio, it is preferable to place the dark adapted patient's eye at low temperature during the laser exposure.