Visual impairment in severe and profound sensorineural deafness

Prevalence and causes of visual impairment among hearing impaired students in Lagos, Nigeria

OBJECTIVES

To determine the prevalence and causes of visual impairment in hearing-impaired students in Lagos, Nigeria and to assess their level of ophthalmic care utilization.

METHODS

Descriptive cross sectional study carried out in a primary school for hearing impaired students in Lagos, Nigeria. Socio-demographic characteristics, medical and ocular history were obtained. Ocular examination comprised of distance and near visual acuity assessment; cover tests; anterior segment examination and direct fundoscopy. Visually impaired students had cycloplegic refraction, dilated fundoscopy and subjective refraction. In-depth interviews were carried out for parents of students requiring referral for further eye care.

RESULTS

One hundred and nine students participated in the study. The prevalence of visual impairment was 19%. The causes of visual impairment were refractive error (11%), amblyopia (6%), cataract (1%) and macular scarring (1%). A lower mean age (p = 0.020) and ocular misalignment (p = 0.037) were associated with visual impairment on multivariate analysis. The spectacle correction coverage was 11% and only 8% of the students had prior ophthalmic care utilization. Ignorance of ocular morbidity and perceived inaccessibility of eye care were cited by parents/guardians as reasons for poor utilization of eye-care services.

CONCLUSION

A high prevalence of visual impairment was found among the hearing impaired students; uncorrected refractive error and refractive amblyopia were the most prevalent causes. The level of prior ophthalmic service utilization was found to be low. It was recommended that ophthalmic services especially refractive services should be made available in schools for the hearing impaired.

Ophthalmic Abnormalities among Children Treated with Cochlear Implants

OBJECTIVES

To review the ocular abnormalities in children treated with cochlear implant.

MATERIALS AND METHODS

A total of 51 children (29 boys, 22 girls) who were under 18 years old, presented previously with severe to profound hearing loss, and underwent cochlear implantation surgery were included in this study prospectively. A detailed ophthalmic examination, including refraction, best corrected visual acuity, ocular motility, slit-lamp biomicroscopy, and dilated fundus examination, was performed for each patient.

RESULTS

Mean age of the patients was 80.10±38.64 (range, 18-168) months. A total of 13 (25.4%) children had at least 1 ophthalmic abnormality. The majority of the detected ophthalmic abnormalities were hyperopia and astigmatism (6 patients had hyperopia, 5 had astigmatism, and 2 had hyperopia plus astigmatism). Strabismus (esotropia) was found in 2 patients, 2 patients had refractive amblyopia, and 2 patients had nystagmus. Moreover, 3 patients had microcornea, 2 patients had cataract, and 1 patient had epiblepharon. Optic disc coloboma (3 patients), choroidal coloboma (1 patient), and pigmentary abnormality (1 patient) were noticed on fundus examination. Congenital rubella syndrome (2 patients), Waardenburg's syndrome (1 patient), and CHARGE syndrome (coloboma, heart defects, choanal atresia, growth retardation, genital abnormalities, ear abnormalities) (1 patient) were also present.

CONCLUSION

Children treated with cochlear implant should be consulted with an ophthalmologist to identify any treatable ocular abnormality.

The Burden of Assessing Ocular Status of Children - Causes and Control

Pediatric ocular diseases can be detectable through a comprehensive eye examination and most of them are preventable once they are discovered. There is a well known fact that children can have ocular pathology such as cataract, refractive errors, strabismus and amblyopia. In children, low vision can have a negative impact on their growth and development; therefore, any visual impairment must be detected as soon as possible to prevent amblyopia development.

Validation of the Strengths and Difficulties Self-Report in Norwegian Sign Language

The majority of studies on mental health in deaf and hard-of-hearing (DHH) children report a higher level of mental health problems. Inconsistencies in reports of prevalence of mental health problems have been found to be related to a number of factors such as language skills, cognitive ability, heterogeneous samples as well as validity problems caused by using written measures designed for typically hearing children. This study evaluates the psychometric properties of the self-report version of the Strengths and Difficulties Questionnaire (SDQ) in Norwegian Sign Language (NSL; SDQ-NSL) and in written Norwegian (SDQ-NOR). Forty-nine DHH children completed the SDQ-NSL as well as the SDQ-NOR in randomized order and their parents completed the parent version of the SDQ-NOR and a questionnaire on hearing and language-related information. Internal consistency was examined using Dillon-Goldstein's rho, test-retest reliability using intraclass correlations, construct validity by confirmatory factor analysis (CFA), and partial least squares structural equation modeling. Internal consistency and test-retest reliability were established as acceptable to good. CFA resulted in a best fit for the proposed five-factor model for both versions, although not all fit indices reached acceptable levels. The reliability and validity of the SDQ-NSL seem promising even though the validation was based on a small sample size.

Prevalence of ophthalmic disorders among hearing-impaired school children in Guntur district of Andhra Pradesh

Purpose:

To estimate the prevalence, causes, and risk factors for visual impairment (VI) among children of school for hearing-impaired (HI) in Guntur district of Andhra Pradesh, India.

Methods:

Children between 6 and 16 years of age available in all the 12 special schools for HI were examined. Visual acuity (VA) testing, ocular motility, and examination of anterior and posterior segment for all children were done. Those having VA of less than 6/12 in better eye underwent cycloplegic refraction. For definition of VI, as per World Health Organization (WHO), VA of better eye was considered. HI was also classified as mild, moderate, severe, and profound as per WHO definitions. Examination for systemic diseases and other associated disabilities was also done.

Results:

In all, 402 children underwent examination. Ophthalmic abnormality was seen in 64 children with a prevalence of 15.9% [95% confidence interval (CI) 14.9%–16.8%], and VI was seen in 29 children with a prevalence of 7.2% (95% CI 4.9%–10.2%). Refractive errors [29 (7.2%)], retinitis pigmentosa (RP) [16 (4%)], and squint [8 (2%)] were the major ophthalmic abnormalities. Thirty-five (54.7%) of the abnormalities were either preventable or treatable. The major cause of VI was refractive error (18) followed by RP (5). Twenty of them (69%) with VI in this study group were treatable. Twenty-two (75.9%) children with eye problem were newly diagnosed. The only risk factor for VI was being mentally challenged (odds ratio: 5.63; 95% CI: 1.89–16.8).

Conclusion:

The prevalence of ophthalmic abnormalities and VI in school for HI was high, and the majority of them were not detected so far. As most of them are easily treatable, it is highly recommended to conduct regular eye examinations in these schools.

Visual function assessment, ocular examination, and intervention in children with developmental delay: A systematic approach. Part 1

Children with special needs form a unique subset with regards to visual function and examination techniques needed to assess them. With more awareness among the general public, neurologists, and pediatricians, these children are referred for assessment to the ophthalmologist or optometrist and sometimes even to the rehabilitation professional at an early age. This clinical practice guideline and review gives a systematic approach for examining the visual functions of a child with special needs. It outlines the procedures to be followed with equipment needed in clinical practice. Functional vision assessment guidelines are also included. This is the first part in a two-part series, with the first part presenting clinical examination guidelines and the second presenting intervention and vision enhancement techniques.

Relative frequency of inherited retinal dystrophies in Brazil

Among the Brazilian population, the frequency rates of inherited retinal dystrophies and their causative genes are underreported. To increase the knowledge about these dystrophies in our population, we retrospectively studied the medical records of 1,246 Brazilian patients with hereditary retinopathies during 20 years of specialized outpatient clinic care. Of these patients, 559 had undergone at least one genetic test. In this cohort, the most prevalent dystrophies were non-syndromic retinitis pigmentosa (35%), Stargardt disease (21%), Leber congenital amaurosis (9%), and syndromic inherited retinal dystrophies (12%). Most patients had never undergone genetic testing (55%), and among the individuals with molecular test results, 28.4% had negative or inconclusive results compared to 71.6% with a conclusive molecular diagnosis. ABCA4 was the most frequent disease-causing gene, accounting for 20% of the positive cases. Pathogenic variants also occurred frequently in the CEP290, USH2A, CRB1, RPGR, and CHM genes. The relative frequency rates of different inherited retinal dystrophies in Brazil are similar to those found globally. Although mutations in more than 250 genes lead to hereditary retinopathies, only 66 genes were responsible for 70% of the cases, which indicated that smaller and cheaper gene panels can be just as effective and provide more affordable solutions for implementation by the Brazilian public health system.

Inframe deletion of human ESPN is associated with deafness, vestibulopathy and vision impairment

BACKGROUND

Usher syndrome (USH) is a neurosensory disorder characterised by deafness, variable vestibular areflexia and vision loss. The aim of the study was to identify the genetic defect in a Pakistani family (PKDF1051) segregating USH.

METHODS

Genome-wide linkage analysis was performed by using an Illumina linkage array followed by Sanger and exome sequencing. Heterologous cells and mouse organ of Corti explant-based transfection assays were used for functional evaluations. Detailed clinical evaluations were performed to characterise the USH phenotype.

RESULTS

Through homozygosity mapping, we genetically linked the USH phenotype segregating in family PKDF1051 to markers on chromosome 1p36.32-p36.22. The locus was designated USH1M. Using a combination of Sanger sequencing and exome sequencing, we identified a novel homozygous 18 base pair inframe deletion in ESPN. Variants of ESPN, encoding the actin-bundling protein espin, have been previously associated with deafness and vestibular areflexia in humans with no apparent visual deficits. Our functional studies in heterologous cells and in mouse organ of Corti explant cultures revealed that the six deleted residues in affected individuals of family PKDF1051 are essential for the actin bundling function of espin demonstrated by ultracentrifugation actin binding and bundling assays. Funduscopic examination of the affected individuals of family PKDF1051 revealed irregular retinal contour, temporal flecks and disc pallor in both eyes. ERG revealed diminished rod photoreceptor function among affected individuals.

CONCLUSION

Our study uncovers an additional USH gene, assigns the USH1 phenotype to a variant of ESPN and provides a 12th molecular component to the USH proteome.

Dual sensory impairment in special schools in South-Eastern Nigeria

In a cross-sectional study to determine the magnitude of dual sensory impairment (DSI-combined hearing and vision loss) in children in single-disability special education schools, children in schools for the blind and schools for the deaf in four states in South-East Nigeria were examined by an ophthalmologist and otorhinolaryngologist to determine the level of their disability and to identify other disabilities if any. Participants were all students with childhood blindness or childhood deafness. The magnitude and causes of DSI and the burden of undetected DSI were the main outcome measures. A total of 273 students were examined. About 7% of these students had DSI out of which over 60% (12/19) was previously undetected. There was more DSI in the blind schools than in the deaf schools (p=0.003). There is a large burden of undetected DSI in children in special schools in Nigeria. There is a need to create awareness of this problem and advocate appropriate screening, rehabilitative and educational strategies for children who have it.

Ocular Disorders in Turkish Children with Sensorineural Hearıng Loss: A Cross-Sectional Study and Literature Review

PURPOSE

To investigate types and frequencies of ocular disorders in children with sensorineural hearing loss (SNHL), and to emphasize the importance of ophthalmological examination in these children.

METHODS

A retrospective analysis of the examination records of children examined in our instutititon between January 2011 and September 2014 was performed. Ocular disorders of children with SHNL were selectively reviewed.

RESULTS

Among 55340 patients, SNHL was present in 110 (0.2%). SNHL was bilateral in 104 patients (94.5%) and unilateral in 6 (5.5%). Ninety-one cases had congenital hearing loss (83%), and 19 (17%) had acquired SNHL. Forty cases (36%) had an ocular disorder, either refractive or non-refractive or both. Seventy cases (64%) had normal ocular examination. No difference was found between congenital or acquired SNHL cases in terms of possessing an ocular disorder (p=0.0962). The most common ocular abnormality was refractive error, mainly hypermetropia (21%). There was no significant difference between the prevalences of ocular abnormalities among cases with different lateralites or severities of SNHL (p=0.051, p=0.874, respectively). Twenty-six cases (23.6%) had SNHL as a component of a genetically defined syndrome. All of them had coexisting refractive or non-refractive ocular abnormalities. Some genetic, non-syndromic abnormalities, including Achondroplasia, Celiac disease, and focal segmental glomerulosclerosis, were diagnosed in four cases, among whom refractive errors and/or strabismus were detected.

CONCLUSIONS

Due to the common coexistence of ocular problems and SNHL in children, ophthalmological screening is crucial. Families and healthcare providers should be informed about the critical role of ophthalmic assesment in these children for their future quality of life.

Ophthalmic pathologies in female subjects with bilateralcongenital sensorineural hearing loss

BACKGROUND/AIM

The high prevalence of ophthalmologic pathologies in hearing-disabled subjects necessitates early screening of other sensory deficits, especially visual function. The aim of this study is to determine the frequency and clinical characteristics of ophthalmic pathologies in patients with congenital bilateral sensorineural hearing loss (SNHL).

MATERIALS AND METHODS

This descriptive study is a prospective analysis of 78 young female SNHL subjects who were examined at a tertiary care university hospital with a detailed ophthalmic examination, including electroretinography (ERG) and visual field tests as needed.

RESULTS

The mean age was 19.00 ± 1.69 years (range: 15 to 24 years). A total of 39 cases (50%) had at least one ocular pathology. Refractive errors were the leading problem, found in 35 patients (44.9%). Anterior segment examination revealed heterochromia iridis or Waardenburg syndrome in 2 cases (2.56%). Dilated fundus examination revealed retinal pathologies in 15 cases (19.23%), including retinitis pigmentosa or Usher's syndrome in 8 cases (10.25%). Most of the Usher's syndrome cases (87.5%) had consanguinity.

CONCLUSION

Screening for congenital SNHL in the early years of life and routine yearly follow-ups are essential for maximizing the rehabilitation of this disabled group. The high rate of visually debilitating syndromic ocular pathologies associated with high frequency of consanguinity doubles the importance.

Impact of correcting visual impairment and low vision in deaf-mute students in Pune, India

Aim:

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Statistical Analysis:

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Conclusion:

Visual Field Abnormalities among Adolescent Boys with Hearing Impairments

The aim of this study was to compare the visual field (VF) categorizations (based on the severity of VF defects) between adolescent boys with hearing impairments and those with normal hearing. This cross-sectional study involved the evaluation of the VF of 64 adolescent boys with hearing impairments and 68 age-matched boys with normal hearing at high schools in Tehran, Iran, in 2013. All subjects had an intelligence quotient (IQ) > 70. The hearing impairments were classified based on severity and time of onset. Participants underwent a complete eye examination, and the VFs were investigated using automated perimetry with a Humphrey Visual Field Analyzer. This device was used to determine their foveal threshold (FT), mean deviation (MD), and Glaucoma Hemifield Test (GHT) results. Most (50%) of the boys with hearing impairments had profound hearing impairments. There was no significant between-group difference in age (P = 0.49) or IQ (P = 0.13). There was no between-group difference in the corrected distance visual acuity (P = 0.183). According to the FT, MD, and GHT results, the percentage of boys with abnormal VFs in the hearing impairment group was significantly greater than that in the normal hearing group: 40.6% vs. 22.1%, 59.4% vs. 19.1%, and 31.2% vs. 8.8%, respectively (P < 0.0001). The mean MD in the hearing impairment group was significantly worse than that in the normal hearing group (-0.79 ± 2.04 and -4.61 ± 6.52 dB, respectively, P < 0.0001), and the mean FT was also significantly worse (38.97 ± 1.66 vs. 35.30 ± 1.43 dB, respectively, P <0.0001). Moreover, there was a significant between-group difference in the GHT results (P < 0.0001). Thus, there were higher percentages of boys with VF abnormalities and higher mean MD, FT, and GHT results among those with hearing impairments compared to those with normal hearing. These findings emphasize the need for detailed VF assessments for patients with hearing impairments.

Electroretinogram assessment of children with sensorineural hearing loss: implications for screening

BACKGROUND

The guidelines of the National Deaf Children's Society recommend that children with sensorineural hearing loss (SNHL) be routinely screened for ophthalmological problems and suggest electroretinography (ERG) to exclude Usher syndrome. The present study reports the nature and prevalence of abnormal ERG findings in a cohort of children with SNHL undergoing ERG with the aim of identifying risk factors for the diagnosis of Usher syndrome.

METHODS

The medical records of children (<18 years of age) with SNHL referred for ERG at Moorfields Eye Hospital, London, between January 2009 and December 2011 were retrospectively reviewed. Patients were included if they had been referred with SNHL by an audiological medicine consultant and the primary indication for electrodiagnostic testing was possible Usher syndrome.

RESULTS

A total of 84 cases met inclusion criteria of which 13 (15%) had ERG findings showing rod-cone dysfunction consistent with a diagnosis of Usher syndrome. Two patients with retinal pigmentary changes had normal ERGs and were diagnosed with rubella retinopathy based on the clinical findings. Risk factor analysis showed that age of ≥8 years at the time of ERG, sex, and bilateral hearing loss were not predictive of a diagnosis of Usher syndrome. However, the presence of or referral for cochlear implants, having relevant symptoms and/or clinical signs consistent with a retinal dystrophy, and profound hearing loss were all highly predictive.

CONCLUSIONS

ERG is a useful diagnostic tool in children with SNHL and should be performed in children with SNHL who have cochlear implants and/or have signs or symptoms of retinal dystrophy. A focused approach could have potential cost-saving benefit.

Common visual problems in children with disability

Children with disability are at a substantially higher risk of visual impairment (VI) (10.5% compared with 0.16%) but also of ocular disorders of all types, including refractive errors and strabismus. The aetiology of VI in children with disability reflects that of the general population and includes cerebral VI, optic atrophy, as well as primary visual disorders such as retinal dystrophies and structural eye anomalies. VI and other potentially correctable ocular disorders may not be recognised without careful assessment and are frequently unidentified in children with complex needs. Although assessment may be more challenging than in other children, identifying these potential additional barriers to learning and development may be critical. There is a need to develop clearer guidelines, referral pathways and closer working between all professionals involved in the care of children with disability and visual disorders to improve our focus on the assessment of vision and outcomes for children with disability.

Hereditary sensorineural hearing loss: advances in molecular genetics and mutation analysis

Hearing loss has a genetic etiology in the majority of cases and is very common. The universal newborn hearing screening program, together with remarkable recent progress in the characterization of genes associated with the function of hearing, have resulted in increased demand and exciting possibilities of detecting the molecular basis of hereditary hearing loss through DNA testing. Future molecular diagnostic assays are expected to offer a greater variety of gene-specific tests, as well as combined mutation panels, which will aid in the management of the impressive genetic heterogeneity observed in hereditary hearing loss, especially in individuals with nonsyndromic forms. This review addresses the genetics of hearing loss, discusses the most commonly offered genetic assays for nonsyndromic hearing loss, with advantages and limitations, proposes a practical testing algorithm, and highlights current developments.

Ophthalmologic findings in a pediatric cochlear implant population

PURPOSE

To report ocular findings in a cohort of children requiring pediatric cochlear implant and to evaluate the usefulness of routine ophthalmologic examination in such children.

METHODS

This was a prospective study of ophthalmologic assessment of 47 consecutive children aged 10 months to 12 years from the cochlear implant program of our hospital.

RESULTS

All children underwent complete ocular assessment consisting of orthoptic and ophthalmo-logic examination, including cycloplegic refraction. A total of 18 children (38.3%) had some form of ocular abnormality, with the majority (14 patients, 29.8%) having refractive errors. Hypermetropia was the most common refractive error (21.3%), followed by astigmatism (8.5%). Strabismus was found in 6 patients, with esotropia being the most common type. Other ocular findings included ptosis (1 patient) and epicanthal folds (3 patients). During the follow-up period, 9 children were fitted with glasses, 3 underwent occlusion therapy, 2 underwent strabismus surgery, and 1 underwent ptosis surgery.

CONCLUSIONS

Thorough orthoptic and ophthalmologic examination is useful for ensuring optimal visual function in children undergoing cochlear implantation.

Ocular morbidity in hearing impaired schoolchildren

AIMS

To determine the pattern and prevalence of ocular morbidity in hearing impaired schoolchildren.

METHODS

A cross-sectional descriptive study was conducted in the three different deaf schools of Kathmandu, Bhaktapur and Kavre districts. All children in the deaf school underwent complete ocular examination. Examination included visual acuity assessment, refraction, binocular vision assessment, and anterior and posterior segment evaluation.

RESULTS

Ocular examination was carried out in 279 children with age range within 5 to 20 years (mean age 14.1 ± 3.14 years). Ocular morbidity was detected in 78 (28%) children with 46 (16.48%) having refractive errors. Seventy eight percent children did not have corrective lenses despite having refractive errors. Two children were found to have pigmentary retinopathy where electro-retinogram findings suggested Usher's Syndrome in one child. Another child was found to have Waardenburg Syndrome.

CONCLUSIONS

Hearing impaired children are at an increased risk of having ocular morbidity. Hence, periodic eye examinations are important in deaf children.

Screening for ophthalmic disorders and visual impairment in a Nigerian school for the deaf

PURPOSE

To detect the presence of ophthalmic abnormalities and visual impairment in deaf students.

METHODS

A cross-sectional survey of all students in the school for the deaf was conducted following ethical clearance from the Ministry of Health. Age, sex, and previous eye examination was recorded for each student as well as visual acuity, penlight eye examination, intraocular pressure, dilated funduscopy, and refraction (when applicable). Data were analyzed with SPSS version 11 and statistical significance inferred at p<0.05.

RESULTS

The 156 (100%) students at the school for the deaf with age range 6-25 years, mean +/- standard deviation of 15.6+/-3.3 years, and modal age of 14 years were studied. A total of 110 (70.5%) had no previous eye examination, 2 (1.3%) students were blind, 5 (3.2%) were visually impaired, 4 (2.6%) had unilateral visual impairment, and 4 (2.6%) had unilateral blindness. Blindness was caused by Usher syndrome in 1 (50%) and bilateral pigmented macular scar in 1 (50%) patient. Uncorrected refractive errors were the leading cause of unilateral visual impairment (75%), visual impairment (60%), and unilateral blindness (50%). Ocular abnormality was present in 53 (34%) students while uncorrected refractive error (18.6%), retina changes (7%), and allergic conjunctivitis (3.8%) were the leading disorders. Previous eye examination was more common among primary school students (p<0.0001) and students with ocular abnormalities (p=0.046).

CONCLUSIONS

Institutions for deaf children should be aware of the high prevalence of ophthalmic disorders and the importance of vision to development of a deaf child, and conduct an initial and periodic eye examination for every intake.

Ophthalmological screening of a paediatric cochlear implant population: a retrospective analysis and 12-year follow-up

AIMS

To determine the nature and prevalence of ophthalmological findings for a cohort of children in a paediatric cochlear implant program and to assist the clinician in devising an investigative plan for this population.

METHODS

Retrospective medical record review of children who underwent multichannel cochlear implantation at a tertiary care hospital between February 1996 and July 2008.

RESULTS

In all, 141 children (mean age 28 months, range 16 months to 9 years) had complete medical record documentation consisting of orthoptic and opthalmological examination, including cycloplegic refraction. A total of 59 children (41.8%) had ocular abnormalities with refractive errors being the most common abnormality. Hypermetropia was the most common refractive error and was found in 21 children (14.8%). Strabismus was found in six patients, with constant esotropia being the most common. Ocular pathology (excluding refractive or muscle abnormalities) were found in nine patients (6.3%). Three patients had syndromes associated with ocular findings including Waardenburg and Usher syndrome. During the follow-up period, 14 children were fitted with prescription lenses, 3 had strabismus surgery, and 2 underwent ptosis.

CONCLUSIONS

Routine orthoptic and ophthalmologic examination can be beneficial in the initial evaluation of children assessed for cochlear implants. Electroretinography is useful in evaluating children with unexplained congenital sensorineural hearing loss, suggestive symptoms including night blindness, unexplained reduction in visual acuity, or delayed motor milestones. Routine yearly follow-up may aid in the detection of changing refractive errors and the possibility of later-onset retinal degeneration.

Evidence that vestibular hypofunction affects reading acuity in children

OBJECTIVE

Despite reported gaze stability deficits in children with hearing impairment and concurrent vestibular hypofunction, the reading difficulties reported in this population have not been linked to the gaze instability. The purpose of this study was to develop a modified version of the MNREAD chart that enabled responses orally or using sign language.

METHODS

Seventy-two typically developing children and 14 children with sensorineural hearing loss with and without vestibular hypofunction participated. We examined: (1) reliability and age related changes in reading acuity scores, (2) the effect of vestibular hypofunction on reading acuity scores, and (3) the relationship between these scores and a test of dynamic visual acuity.

RESULTS

The test was reliable (ICC (3,2)>or=0.86). Reading acuity scores were significantly worse in children with vestibular hypofunction (p<or=0.002). Furthermore, reading acuity scores correlated with dynamic not static visual acuity scores (r=0.55, p<0.001).

CONCLUSIONS

These results imply that the gaze instability due to vestibular hypofunction affects reading ability in young children.

Evidence-based overview of ophthalmic disorders in deaf children: a literature update

BACKGROUND

Deaf children are heavily reliant on the sense of vision in order to develop efficient communication skills and explore the world around them. Any ophthalmic disorder may thus negatively impact on this process, especially if it is unrecognised in the early years of life. These disorders may be correctable (such as myopia) or treatable (such as cataract), and their early identification is of the utmost importance to optimise language development (spoken or sign, or both) and develop social cognition. Those children with non-correctable and non-treatable visual disorders, like retinitis pigmentosa in Usher syndrome, require multiple environmental adaptations and appropriate support services and information.

AIM

: To review the accumulated scientific knowledge on ophthalmic disorders in deaf children and assess the quality of evidence published in the literature in order to contribute to better diagnosis and management of these conditions.

MATERIAL AND METHODS

The project reviewed more than 1000 published papers and other sources. 191 papers complied with the aims of the study and were used in the project. From these studies, 95% were based on type III or IV evidence (mainly descriptive studies or case reports). Only 3% were based on type II evidence and 2% on type I evidence.

RESULTS-CONCLUSIONS

The main conclusions of this project are: a) the overall quality of evidence in the literature concerning deaf children and their ophthalmic problems is very low, b) the prevalence of ophthalmic problems in deaf children is very high (approximately 40% to 60%) and these problems may remain undetected for years although they may have a serious impact on children's acquisition of communication skills, c) screening for ophthalmic problems in deaf children should be encouraged and specialist ophthalmic examination should be carried out as soon as the diagnosis of deafness is confirmed irrespective of age, and may need to be repeated at intervals following diagnosis, d) families should be informed about the nature of the screening process in discussion with the relevant professionals and appropriate information should be available in a range of formats and in different community languages, e) professionals administering the tests should be familiar with the needs of deaf children with ophthalmic problems and should be sensitive to the communication needs of the child, especially undertaking behavioural testing where their collaboration is needed, f) while orthoptists can perform the majority of psychophysical tests (visual and stereo acuity tests, ocular motility tests, etc.) a comprehensive opthalmologic assessment by slit lamp biomicroscopy, streak retinoscopy, direct and indirect ophthalmoscopy, intraocular pressure measurement etc is required. Electrophysiologic testing to help identification of Usher syndrome may also be required, and finally g) serial hearing assessments of children with dual sensory deficits are needed to monitor hearing thresholds, to optimise hearing aid use and to ensure timely referral for cochlear implantation for those who need it.

Hereditary non-syndromic sensorineural hearing loss: transforming silence to sound

Tremendous progress has been made in our understanding of the molecular basis of hearing and hearing loss. Through recent advances, we have begun to understand the fascinating biology of the auditory system and unveiled new molecular mechanisms of hearing impairment. Changes in the diagnostic impact of genetic testing have occurred, as well as exciting developments in therapeutic options. Molecular diagnosis, which is already a reality for several hearing-associated genes, will doubtlessly continue to increase in the near future, both in terms of the number of mutations tested and the spectrum of genes. Genetic analysis for hearing loss is mostly used for diagnosis and treatment, and relatively rarely for reproductive decisions, in contrast to other inherited disorders. Inherited hearing loss, however, is characterized by impressive genetic heterogeneity. An abundance of genes carry a large number of mutations, but specific mutations in a single gene may lead to syndromic or non-syndromic hearing loss. Some mutations predominate in individual ethnic groups. For clinical and laboratory diagnosticians, it is challenging to keep abreast of the unfolding discoveries. This review aims to provide the framework pertinent to diagnosticians and a practical approach to mutation analysis in the hearing impaired.

A clinical evaluation of ophthalmic assessment in children with sensori-neural deafness

BACKGROUND

Since 1991, children with sensori-neural deafness and their families within Southern Derbyshire have been supported by a multiagency approach to their diagnosis and management.

RESULTS

One hundred and twenty-two children were seen at the Child Development Centre for an holistic assessment, and 110 of these children have had an ophthalmic assessment, of whom 48 (43.6%) were found to have ophthalmic abnormalities. These included 43 children (39.1%) with refractive errors, ranging from mild to severe. Of 82 children with uncomplicated deafness, 26 (31.7%) had refractive errors. The prevalence of ophthalmic problems was higher than the prevalence in hearing school children in the literature and in local pre-school children. There were six cases of Usher syndrome. Twenty-one children had more than one eye defect. The findings indicate that deaf and hearing impaired children are two to three times more likely to develop ophthalmic abnormalities than their hearing peers, which makes early detection of paramount importance. An important local outcome has been the establishment of guidelines for ophthalmic assessment to include assessment of vision and screening for Usher syndrome by electro-physiological testing at aged 7 years and above. Screening has been completed to date in 78 children with congenital sensori-neural deafness.

CONCLUSIONS

Sensitive and efficient ophthalmic assessment and management are essential for all deaf and hearing impaired children and national guidelines need to be established for both assessment of vision and screening for Usher syndrome, based on further evaluated research.

The molecular genetics of Usher syndrome

Association of sensorineural deafness and progressive retinitis pigmentosa with and without a vestibular abnormality is the hallmark of Usher syndrome and involves at least 12 loci among three different clinical subtypes. Genes identified for the more commonly inherited loci are USH2A (encoding usherin), MYO7A (encoding myosin VIIa), CDH23 (encoding cadherin 23), PCDH15 (encoding protocadherin 15), USH1C (encoding harmonin), USH3A (encoding clarin 1), and USH1G (encoding SANS). Transcripts from all these genes are found in many tissues/cell types other than the inner ear and retina, but all are uniquely critical for retinal and cochlear cell function. Many of these protein products have been demonstrated to have direct interactions with each other and perform an essential role in stereocilia homeostasis.

Medical evaluation of pediatric hearing loss. Laboratory, radiographic, and genetic testing

Specific investigations of pediatric hearing loss are based on the history, physical examination, and age of the patient. The radiographic investigation of choice is high-resolution CT of the temporal bone. Patients with a dilated vestibular aqueduct need to be investigated further for Pendred syndrome. Screening for mutations in connexin 26 has become increasingly available in many centers and should be performed in all cases of nonsyndromic hearing loss. It is important to understand the implications and pitfalls of genetic testing. Genetic counseling is necessary.

Genetics of hearing impairment

Our understanding of the genetics of hearing impairment (HI) has advanced rapidly during the last decade. In this review, we focus on HI due to single gene abnormalities, highlighting some of the more common causes of syndromic HI. We also outline the current state of knowledge of the genetics of non-syndromic HI. The most significant clinical advance has been the finding that mutations in GJB2 cause half of moderate-to-profound congenital hereditary deafness in many world populations. The implications of this finding for screening and genetic counseling are discussed.

Changes in the aetiology of hearing impairment in deaf-blind pupils and deaf infant pupils at an institute for the deaf

An aetiological study was performed on 57 pupils at the deaf-blind department of the Institute for the Deaf at Sint-Michielsgestel, The Netherlands, in the school year 1998-1999 and on 49 deaf-blind pupils at the same department in the school year 1986-1987. The pupils were 5-20 years of age. In addition, the aetiologies were studied in 55 deaf infant pupils in 1998 and compared with those of 68 deaf infant pupils in 1988. Their age was 1-5 years. All the pupils showed hearing impairment with thresholds of >60 dB HL. Among the deaf-blind pupils and deaf infant pupils, there were several cases with rare hereditary syndromes. The prevalence of acquired causes of deafness, especially congenital rubella, had decreased over the years, whereas perinatal causes of deafness had increased. Chromosomal anomalies were found in 15% of the infant pupils in 1998. Over the study period, the percentage of pupils with multiple handicaps increased from 25 to 38%.

Population-based genetic study of childhood hearing impairment in the Trent Region of the United Kingdom

The objective of the study was to investigate childhood hearing impairment in a population-based sample from a genetic perspective. Participants included 82 families with hearing-impaired children (aged 4-13) previously ascertained in the Trent Health Region. A questionnaire was mailed to all families, followed by a home visit and Connexin-26 35delG mutation screen. The Connexin-26 35delG mutation was identified in seven families (approximately 10 per cent of non-syndromal hearing impairment). Children of these families were significantly more likely than children with other modes of inheritance to have a profound hearing loss with a flat audiogram profile. The families of children with a significant admission to a neonatal intensive care unit were significantly less likely to have had genetic counselling. Eight families visited were found to have features suggestive of a genetic syndrome that had not been previously assigned a specific diagnosis. The study concluded that hearing-impaired children should be investigated systematically according to an agreed-upon protocol, which should include Connexin-26 35delG mutation analysis at least for those with severe-to-profound hearing loss.

Audiologic evaluation of hearing-impaired infants and children

With the advent of auditory brainstem response (ABR) and otoacoustic emission (OAE) testing, as well as the widespread use of universal hearing screening programs, the audiologic assessment of hearing-impaired infants and young children has become more frequent in recent years. When assessing a hearing-impaired infant, it is necessary to obtain as much frequency and ear specific information as possible prior to selection of hearing amplification. An overview of the battery of tests and the need for a diagnostic center that is well versed in both physiologic and behavioral tests will be addressed.

Epidemiology of permanent childhood hearing impairment in Trent Region, 1985-1993

This retrospective study of permanent childhood hearing impairment (PCHI) > or = 40 dB HL in children born between 1985 and 1993 and resident in Trent Health Region, achieved an ascertainment of 92.9% of that expected from previous studies and 100% for the subset of children born between 1985 and 1990. The prevalence rate of all permanent hearing impairment > or = 40 dB HL for the birth cohort 1985-90 is 133 (95% confidence interval, (ci) 122-145) per 100,000 live births (1 in 750). Sixteen per cent of PCHI were postnatally acquired, late-onset or progressive impairments. Excluding these, the prevalence rate for congenital impairments is 112 (ci 101-123) per 100,000 (1 in 900). The rate for profound impairments > or = 95 dB HL is 24 (ci 20-30) per 100,000 live births (1 in 4150). Prevalence was increased sixfold for children with a history of neonatal intensive care and 14-fold for children with a family history, compared with children with no risk factors. A more than two-fold increase in prevalence was seen in Asian children. For the congenitally-impaired children born between 1985 and 1990, 29% had a stay in neonatal intensive care > or = 48 hours, 30% had a family history of permanent childhood hearing impairment, and 12% had a cranio-facial abnormality (CFA). Over 59% were potentially detectable by a targeted neonatal screening programme using these three high-risk factors. For 1985-1993, the overall yield of the targeted neonatal screening programmes available in three of the 11 health districts was 15% but increased over time. The overall yield from the Health Visitor distraction test was 30% but lower in districts with neonatal screening programmes. Only 59% of children had a stated aetiology, classified by time of onset into genetic, including syndromes and CFA (41%), pre- or peri-natal (10%), post-natally acquired (6%), and uncertain onset (2%). Just under 40% of the children were said to have another clinical or developmental problem, about half of whom had at least two additional problems. The median age at referral, confirmation of the impairment, prescription of the hearing aid and fitting of the hearing aid were, respectively, 10.4 months, 18.1 months, 24.4 months and 26.3 months. A more severe impairment was associated with earlier age. Small improvements in the median age of hearing aid prescription and fitting were seen over time. Twenty-five per cent of children were referred for genetic counselling, the proportion increasing systematically with the severity of the impairment. Based on evidence of the yield from hearing screens we suggest a wider implementation of neonatal screening and further consideration of the role of the health visitor distraction test in the identification of children with PCHI. To facilitate further assessment of services for hearing-impaired children we suggest implementation of a co-ordinated shared list of children with permanent hearing impairment on a region-wide basis to provide adequate numbers for comparison over time, and the routine collection of a minimum set of data for each child.