Available evidence suggests that ophthalmologic screening and detection of visual problems in deaf children is important because the vast majority of knowledge is obtained through the senses of sight and hearing, some through the tactile, kinesthetic and olfactory senses. When one of these is seriously impaired, the other is used to compensate the disability, so the deaf population may compensate by making greater use of visual-perceptual cues than their normal hearing peers, and thus even a mild refractive error may reduce the visual cues available to the deaf mute person.
Secondly, many researches have reported high incidences of ophthalmologic abnormalities among deaf children compared with the hearing population of the same age. A review of the literature suggests 35 to 57% visual defects among hearing-impaired children.[2–8] Therefore, particular attention must be paid to ocular abnormalities in deaf children, as their early detection and proper treatment are the best assurances for the maximum possible social and professional performance of these students.
The aim of the study was to determine the nature and prevalence of ophthalmologic abnormalities in students attending deaf mute schools (special education schools) in a large city in western India.
Materials and Methods
Permission was sought and obtained from the principals of special education schools for the hearing impaired in and around Pune city. All these schools had admission policies to include only hearing-impaired children; normal children and those with other handicaps were officially not admitted into the schools. A team of ophthalmologists, optometrist and social worker visited each school. The principals and teaching staff of the schools were briefed about the eye examination.
Each child's hearing and speaking ability was recorded as reported by the teachers, along with the cause and type of deafness, where this information was available. The hearing ability had been measured in decibels. Hearing impairment was classified as mild, moderate, severe and profound deafness as per World Health Organization norms.
The children were examined with a school teacher near them and they responded by sign language that was interpreted by the teacher. The ophthalmologic work-up included visual acuity assessment, pupillary evaluation, ocular motility examination, and alternate cover test and fundus examination.
Snellen's E–Chart was used for examining children over seven years of age, and Kay picture chart was used for younger children. Near-vision testing (33 cm) was done first, and then visual acuity at six meters was examined. The child was required to correctly match the direction of his fingers to the arms of the E. After the child responded easily, each eye was tested separately. Cycloplegic refraction was done where indicated. Myopia was defined as an error more than or equal to −0.5 diopter (D), hypermetropia as more than or equal to +1.0 D, and astigmatism as more than or equal to + 0.5 D. Amblyopia was defined as best corrected visual acuity of less than 20/200 in either eye resulting from anisometropia, strabismus or large astigmatic error. Extraocular muscle imbalance was noted when eye misalignment exceeded 10 prism diopter (>5 degrees).
Children who needed more detailed evaluation were referred to the H. V. Desai Eye Hospital's pediatric ophthalmology department.
Nine hundred and one students of 14 schools for the hearing impaired in and around Pune city were examined. Males comprised 554/901 (61.5%), and the age ranged from four to 21 years, averaging 12.7 years (SD 4.35). Hearing impairment had been certified by the doctor before admission to the school.
In this study six hundred and eighty-five children 685/901 (76.0%) had a normal ophthalmologic examination, while 216/901 (24.0%) children had ocular problems. The details of ocular morbidity observed are shown in Table 1.
In this study, 257/901 (28.5%) children were profoundly deaf, 476/901 (52.8%) were severely deaf, 94 (10.4%) were moderately hearing-impaired and 74/901(8.2%) children were mildly deaf. The cause of deafness was known in 194/901(21.5%) children. The majority, 382/901 (42.4%) were not able to speak at all, 369/901 (41.0%) were able to speak, and only 150/901(16.6%) children were verbally articulate.
Prevalence of refractive errors in the present study was 167/901 (18.5%). Hypermetropia was found in 41/167 (24.5%) children, while myopia was found in 113/167 (67.7%) and astigmatism was found in 13/167 (7.8%) children. Of these, ten were wearing spectacles at the time of examination, and 18 children with refractive errors had vision better than 20/40 before they were checked. With appropriate spectacle correction, 104 had best corrected visual acuity better than or equal to 20/30. Visual acuity less than 20/60 on presentation was detected in 50 (5.5%) children. All except three (0.3%) improved to better than or equal to 20/60. These three children were provided low-vision aids.
Most children had never undergone any eye checkup previously; 232/901 (25.7%) children had been examined the previous year by our team, though no spectacles were dispensed to the children and only a prescription for glasses had been given at that time.
Hearing-impaired children rely almost entirely on their visual senses to learn about their environment. If a visual handicap is added to the auditory handicap it would affect such a child more than it would affect a normal child. Refractive errors and amblyopia are easily treatable and it would be a shame if such a hearing-impaired child does not get proper eye care attention. Our study showed that 24.0% hearing-impaired children had eye problems as compared to 48 (43.6%) ophthalmic abnormalities in sensorineural deaf children in the UK, 100 (35.8%) with ocular problems in deaf mute students in China, 178 (33%) having minor ocular abnormalities in Australia and 95/165 (57.6%) deaf mute children having ocular abnormalities in Malaysia. Table 2 compares the findings of this study with other similar studies in published literature. The percentage of ocular problems was more in some other studies as they may have considered children with severe hearing loss and perhaps additional handicap. An evidence-based review of ophthalmic disorders in deaf children done in Greece found that the overall quantity of evidence in the literature concerning deaf children and their ophthalmic problems was low. The prevalence of ocular problems in deaf mute children was high and may remain undetected for years, having a serious impact on the development of their communication skills. Only 10 of the 167 children with refractive errors were using spectacles. Screening for ophthalmic problems amongst the deaf should be encouraged and their caretakers (parents and teachers) should be sensitized to the same.
Eye care professionals administering visual acuity tests should be sensitive to the communication needs of the deaf children. A comprehensive eye care examination is mandatory and should be repeated every few years as the child's visual and refractive status may change. Ophthalmologists should especially look out for retinal pigment abnormalities.
In the study group, the most common ocular abnormality was refractive error. Of the 901 deaf children examined, 167/901 (18.5%) had one or more refractive errors. The frequency of refractive errors in the present study was twice that found in the normal hearing population. The next most common ocular abnormality was found to be strabismus, which has been determined at different rates in previous studies. The incidence of manifest strabismus has been cited as 1.3% and 3.7% from overseas studies. In our study, 12/901 (1.3%) of the children had strabismus, which was significantly greater than in the normal population. Higher prevalence of refractive and strabismic errors in the hearing-impaired population, who may be amenable to spectacle, surgical or orthoptic treatment, makes early diagnosis essential because this population is especially dependent upon vision for their maximal cognitive, psychological and emotional development.
The present study shows an increased prevalence of refractive errors and other ocular problems in deaf mute children.
Ophthalmologists play an important role in organizing such screening programs so that related diseases may be diagnosed and treated. Early ophthalmologic assessment of the hearing-impaired is advisable to detect any ocular visual impairment, followed by correction to help in the academic and social performance of these children.
Mr. Shahbaj Shaikh, Hema Kale, all the principals and teachers of 14 Deaf- mute schools, Dr. Roma Deshpande, Dr Pankaj Mangrulkar Dr. Kuldeep Dole, for reviewing the manuscript. Niranjan Pandya and the District Blindness Control Society, Pune for providing spectacles.
1. Woodruff ME. Differential effects of various causes of deafness on the eyes, refractive errors
, and vision of children Am J Optom Physiol Opt. 1986;63:668–75
2. Guy R, Nicholson J, Pannu SS, Holden R. A clinical evaluation of ophthalmic assessment in children with sensori-neural deafness Child Care Health Dev. 2003;29:377–84
3. Hanioğlu-Kargi S, Köksal M, Tomaç S, Uğurba SH, Alpay A. Ophthalmologic abnormalities in children from a Turkish school for the deaf Turk J Pediatric. 2003;45:39–42
4. Elango S, Reddy TN, Shriwas SR. Ocular abnormalities in children from a Malaysian school for the deaf Ann Trop Paediatr. 1994;14:149–52
5. Siatkowski RM, Flynn JT, Hodges AV, Balkany TJ. Ophthalmologic abnormalities in the pediatric cochlear implant population Am J Ophthalmol. 1994;118:70–6
6. Ma QY, Zeng LH, Chen YZ, Li ZY, Guo XM, Dai ZY, et al Ocular survey of deaf and mute children Yan Ke Xue Bao. 1989;5:44–6
7. Nicoel AM, House P. Ocular abnormalities in deaf children: a discussion of deafness and retinal pigment changes Aust N Z J Ophthalmol. 1988;16:205–8
8. Regenbogen L, Godel V. Ocular deficiencies in deaf children J Pediatr Ophthalmol Strabismus. 1985;22:231–3
9. Nikolopoulous TP, Lioumi D, Stamatakis, O'Donoghue GM. Evidence based overview of ophthalmic disorders in deaf children: a literature update Otol Neurotol. 2006;27:S1–24
10. Dandona R, Dandona L, Srinivas M, Sahare P, Narsaiah S, Muñoz SR, et al Refractive error in children in a rural population in India Invest Ophthalmol Vis Sci. 2002;43:615–22
11. Murthy GV, Gupta SK, Ellwein LB, Muñoz SR, Pokharel GP, Sanga L, et al Refractive error in children in an urban population in New Delhi Ophthalmol Vis Sci. 2002;43:623–31
Source of Support: Nil
Conflict of Interest: None declared.