الفهرس 
Literature ReviewOnly 14 pages are availabe for public view
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Abstract
The biological effects which may be induced by ultrasound in the eye studied experimentally for decades in order to examine the safety of ophthalmic diagnostic systems and to clarify the therapeutic applications of intense ultrasound. The therapeutic use of ultrasound due to its hyperthermia has accepted much interest in ophthalmology. The therapeutic applications of ultrasonic energy are also considered for the treatment of glaucoma, ocular tumour, retinal detachments, coagulation of lens protein, disruption of vitreous membranes and vitreous hemorrhages.
Free radicals in addition to hydrogen peroxide produced by exposure of cells to ultrasound can lead to DNA damage and causes damage to biological tissue that is a critical event in the etiopathogenesis of various diseases. The harmful effect of free radicals causing potential biological damage called oxidative stress arises in biological systems when there is an overproduction of reactive oxygen species on one side and insufficiency of antioxidants on the other.
Systemic and topical use of antioxidant substances for the medical treatment of numerous diseases as well as additional protection of the eye against the negative action of free radicals and other reactive species has become widespread during the past years.
The present study was designed to assess the molecular changes of rabbit eye layers by FTIR and the function of the retina by electroretinogram after insonification and the possible protective role of oral ascorbic acid (vitamin C) and -carotene supplementation.
Newzealand albino rabbits of both sexes classified into five groups. group (I) used as control group. The eyes of group (II) Insonificated with continuous ultrasound waves (1.5 W/cm2 at 2.8 MHz) for 20, 40 and 60 minutes. group (III) vitamin C instillation starting one hour before insonification until the end of ultrasound exposure and group (IV) insonificated after -carotene supplementation. group (V) was insonificated after compination of the two treatments. The animals were dark adapted for one hour before the electrophysiological recording then were decapitated after 20, 40 and 60 minutes and eyes were enucleated then retinae and cornea were removed and prepared for analysis by Fourier-transform infrared spectroscopy (FTIR) to study corneal and retinal structure modifications. Total soluble protein content and FTIR spectra of pool samples of rabbit cornea and retina were recorded in the range 4,000–1,000 cm-1 .
The results of soluble protein content of cornea showed high significant decreased (p˂0.001) by increasing exposure time to ultrasound. The most prominent change in FTIR was detected in NH-OH and finger print regions of cornea after insonification with ultrasound for 60 minutes. The measured parameters showed a positive result for antioxidant in reducing ultrasound effects on the corneal tissue.
Statistically significant reduction (P˂0.05) in a- waves amplitude after insonification and exceeding with increased exposure time 20, 40 and 60 min was observed. The amplitudes of a-wave after treatmrnt with topical and supplemented or both remained significantly larger compared with those exposure to US only but its latency lower than that found in insonified groupes. Also, the b-waves were found to follow the same behavior as a-wave.
The data indicate that ultrasound waves have the potential to cause significant biological effects in molecular secondry structure of corneal and retinal tissue. Also ERG changes and its effect on the retinal function confirm its sensitivity to the ultrasound waves. Supplementation of antioxidant preserves the corneal tissue especially at short insonification time. Retinal function was affected due to insonification and the study recommended considering oral β-carotene antioxidant in combination with vitamin C eye drops as a medical tool and personal protective in ultrasound equipment in provide safety.