الفهرس 
Introduction and review of literatureOnly 14 pages are availabe for public view
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Abstract
The Neodymium:YAG(ND:yag)laserhasbeen available for investigation use in the united states since July 1982.The initial investigative studies were to testthe safety and effectiveness of theND-YAGlaser in cutting the lens posterior capsule .
Our aim of work is to use this kind of laser (ND-yag) to study its effect after exposure on eye tissues (cornea-lens-retina), after 4and 8days.Allthe samples were exposed toND-yag laser with the same intensity (0.01W/cm2),but with different times (0.25 and0.1 sec)and study the following:
1-Electroretinogram:
The change in the amplitude of b-wave decreased than the normalin dark and lightas well asexposure times( 0.25& 0.1 sec) . It shows a larger values atlower exposure time (0.1 sec) .The b-wave amplitude starts to close the normal values after 8days f rom exposure . The recovery of the retina is faster in lower time than larger one.
2-Dielectric properties:
1-The values of (ResistantR, capacitance C, impedance Zandphase angle Φ) aremeasured in the room temperature for all tissues (cornea, lens and retina) ofthe left andrighteyebefore and after exposure. All theseare parameters measured after 4 and 8 days from exposure .Impedance values increases after exposure than its normal, this leads to the less of the conductivityσ, the permittivity ε’ to the tow times(0.1and0.25 sec).The lower values are corresponding to the longtime 0.25 secthan the shorttime0.1 sec. After 4days the conductivity and permittivity values change toward the normal values and closeto it after 8days from exposure.
2- The relaxation time τ values lower immediately after exposurethanthe normalforthetow times and closefrom its values after8days for all the exposed samples .All eye tissues recovery are fast forthelower exposuer time.
3-optical properties:
The obtained spectrum of the eye tissues (retina, cornea, lens and sclera) contains twopeaks at 1450nm and 1950nm ,are correspond to water molcules with different bonds betweenhydrogen &.These results indecatesthat the laser absorpedby tissues andaffect on the bond between (H-O-H).This is a cheimcaly effect oflaseratlow power & expouser time.
The three different techniques in this study , show the effect of Nd-Yag laser as well ashelpingto prevent any risks or side effects occure during the oculartissues surgery.