EFFECT OF ND-YAG LASER ON DIELECTRIC PROPERTIES OF RABBIT EYE

This paper is an attempt to investigate the effect of neodymium yag ( Nd:YAG) laser exposure during eye treatment (1064nm, 0.01w/cm2, spot size 450µm, duration time 9 n sec., 30 pulses per sec and time exposure, 0.25 (group A) and 0.1 sec (group B)). We intend to measure the dielectric properties of eye tissues and correlate them with structure. Values of the relative permittivity, dielectric loss and conductivity έ, ε'' & s, are measured for various rabbit ocular tissues (cornea, lens and retina) at the frequency range 100Hz -100kHz before and after laser exposure. The aim of this work is to test the functional state of the eye tissues exposed to laser beam of the same intensity and duration as that used in lens posterior capsulotomy after cataract surgery, by the use of dielectric method. We tried to adapt the physical conditions surrounding the exposed eye during exposure. The obtained results showed that, for the whole eye, as well as for all eye tissues, both values of permittivity and conductivity showed remarkable decreases than normal values, immediately after laser exposure, for both group A & B and this reduction begins to diminish with days after exposure approaching normal values approximately after 8 days of exposure. It is evident that, although laser interacts with all cell membrane structures responsible for transport phenomena leading to changes in the dielectric properties, this interaction depends on the tissue type, special function of membrane and magnitude of exposure power and time of exposure which must accurately considered during choosing the laser treatment conditions and the tissue to be treated.