EFFECT OF ULTRASOUND ON BIOPHYSICAL PROPERTIES OF MAMMALIAN EYE

Abstract

The use of therapeutic ultrasound is not new to ophthalmology, ultrasonic energy, properly controlled, can produce a unique type of tissue destruction that has application as an effective surgical tool in ophthalmology. The absorption of ultrasound occurs diffusely within the retina, choroid and sclera to produce temperature elevations within these structures.

The closest, present analog to therapeutic ultrasound is the laser. While similar in some aspects, ultrasonic energy is considerably different in others. Like the laser, ultrasound can be focused, and the focal point can be positioned accurately on the surface of the eye. Unlike the laser, ultrasound does not require specific optical properties to absorb energy thus, it can operate independently of tissue pigmentation. Ultrasonic energy can be focused through optically opaque media such as the sclera, cataract or vitreous hemorrhage and with ultrasonic techniques, a defined volume of tissue can be heated rather than a surface heating effect as typical with retinal laser technology (Lizzi et al, 1981).

The aim of the present investigation is to analyze the influence of ultrasound on the electroretinogram and ultrastructure of rabbit retina, focusing on anatomical and functional changes after therapeutic doses of ultrasound.

In the present work, the records (extra-cellular recording) were recorded for dark adaoted white Newzeland rabbits before and after insonification of rabbit with continuous ultrasound wave •. varying intensities and aurations of exposure intensities from 0.5 up to 3 W/cm2 in the range of therapeutic doses were •used at exposure durations of 1 up to 30 minutes the transducer was operated at 2.8, 4.5, and 10.8MHz.

Histopathologicals study was achieved for all the above cases to clarifY the results,also the biometric parameters ,;axial length (AL), anterior chamber depth (AD), lens thickness (LT), vitreous length (VL) of rabbit eye tissue were investigated.