To Investigate the Refractive Error and Visual Field in Hearing Loss Individuals

Document Type : Original Article

Authors

1 Refractive Error Research Center, Mashhad University of Medical Sciences, Mashhad, Iran

2 Department of Optometry, School of Paramedicine Sciences, Mashhad University of Medical Sciences, Mashhad, Iran

3 Department of Speech Therapy, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran

4 Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran

Abstract

Purpose:
To investigate the refractive error and visual field abnormalities in high school students with hearing loss problems of Tehran, Iran.
Methods:
In this cross sectional study sixty-four eyes were tested for visual fields and refractive error. All individuals had intelligence quotient (IQ) of more than 70 using Wechsler Intelligence Scale for Children-revised (WISC-R). Status of hearing loss was classified based on the severity and time of onset. We investigated their visual fields to measure Foveal Threshold (FT), Mean Deviation (MD) and status of Glaucoma Hemifield Test (GHT) by using Humphrey field analyzer automated perimetry.
Results:
Our investigation in students with hearing loss showed the high amount of anomaly in visual field in comparison with normal ones. The results demonstrated that profound hearing loss was noted in 50% of them Congenital and acquired hearing loss were seen in 57 (89.1%) and 7 (10.9%) subjects, respectively. Frequency of abnormal VF based on the GHT, MD and FT in hearing loss were 31.2%, 59.4% and 40.6%, respectively.  All types of abnormal visual fields such as FT،MD and status of GHT were not associated with the type and severity of hearing loss. Frequency of early defect was 26.6% which was the largest frequency of visual field defect in deaf students. None of the abnormal factors like FT, GHT and MD has a relationship with type and severity of hearing loss in deaf people. The most frequent refractive error type was hyperopia with astigmatism (37.5%) and the least one was patients with myopia (9.4%). Only 12.5% of hearing loss students had corrected distance visual acuity less than 10/10.
Conclusion:
The larger frequency of foveal threshold defects observed in children with hearing loss than the other visual field defects. We concluded that a deaf boy is at greater risk of visual filed abnormalities than hearing boys.

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References

 
Journal of Paramedical Sciences & Rehabilitation
Volume 6, Issue 3
September 2017
Pages 21-29

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