الفهرس 
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Abstract
Strabismus (ocular misalignment) affects up to 4% of the general population(Engle,2007). Many cases of non-syndromic early childhood strabismus seem sporadic, recessive and dominant inheritance patterns can be inferred from familial cases(Volk et al.,2010)
The function of the mature vestibular system is to stabilize the position of the eyes, head and body in space,and helps to maintain an upright stance.
The vestibular system is responsible for sensing motion of the head and maintains stability of images on the fovea of the retina and postural control during that motion. When functioning normally, the vestibular receptors in the inner ear provide an exquisitely accurate representation of the motion of the head in 3 dimension (Minor,1998) .
Hence,this work was designed to evaluate vestibular functions in patients with strabismus and to find out if strabismus affect these functions or not.
This study included 30 patients with strabismus .aged between10-33 years. Patients in this study were selected from outpatient clinic, Ophthalmology department, Sohag University hospitals
-Equipments:
1. Sound treated room IAC model,1602.
2. Computerized two channel pure tone audiometer Madsen model,922.
3. Immitancemeter Amplaid model,775
4. Computerized Videonystagmography(VNG)ICs chartr with alight bar designed to ensure avisual field of 40 degree of both horizontal and vertical planes
5. Water caloric irrigator ICs chartr model ,NCI-480
6. Computerized Dynamic Posturography system,Neurocom(Smart Equi-test)
-Methods:
Full history taking
Detailed history of dizziness(Appendix Ι)
-Full E. N. T. examination .
-Neurological examination : all our patient were neurologically free.
- Ophthalmological examination
Assessment of the visual acuity of each eye, Assessment of stereo acuity
Assessment of ocular alignment, Assessment of ocular motility.
-Basic Audiological Evaluation
-Office tests for vestibular evaluation
-Office tests for vestibular evaluation:
Head shake test, Head thrust test, Dynamic visual acuity test,CTSIB (Modified Clinical Test for Sensory Interaction of Balance),Fukuda Stepping Test,Sharpened Fukuda Stepping Test , ,Videonystagmography(VNG),Computerized Dynamic Posturography(CDP).
-Results:
Hearing evaluation of our patient show normal hearing level in our selected cases with excellent speech discrimination and all patients were with type A tympanogram and preserved Acoustic reflexes which reflect normal middle ear function.
These vestibular tests either office tests or lab. Tests , were done 3times one before eye surgery and twice after surgery(one and two months)after eye surgery.
In the selected 30 patients ,that fulfilled our criteria ,the most common type of strabismus was exotropia ,about half of cases (14 out of 30 patients )followed by esotropia (11out of 30)and both alternating esotropia and exotropia was 2 and 3patient respectively.
The angle of strabismus was from ±15to ±45.because of wide range of the angle we classified our patients into three sub groups ,those with angle from(15-25)was 7patients ,and from( 26 -35)was 15patients and the 3rd one was(36-45)was 8 patients .
All participants in this study had no history of dizziness after detailed history of vertigo.
In office tests for vestibulo-ocular pathway, inspite of all patients had no history of dizziness, in pre-operative tests ,36.6% of patients, had abnormal results in dynamic visual acuity compared to the 2other tests were 26.6 %and16.6% in head thrust and head shake respectively.
Concerning office tests, for vestibulo-spinal pathway,43.3% had abnormal sharpened fukuda stepping test, followed by10 patients ,33.3% and 4 patients ,13.3% had abnormal CTSIB and fukuda stepping test .
The main findings in the present study are the following:
Improvement of vestibulo-ocular office test and vestibulo-spinal office test.the improvement was marked in more difficult tests(dynamic visual acuity and sharpened fukuda stepping test).
Also ,the improvement was stable by time after one month and 2months.
VNG finding post –operatively ,there was marked improvement in ocular motility testing, the improvement mainly in latency, on the other hand no changes occurred in caloric test results .Also positional test revealed only one patient with positional vertigo and remain post –operatively having positional vertigo but with no nystagmus.
There is significant improvement of SOT of CDP specially in condition 6which denoting preferential pattern of posturography .In this condition patient relay more in vestibular function and need to neglect the abnormal visual stimuli, that occur through visual surrounding in CDP.