Partially sighted Swedish schoolchildren

Assessment, Counseling, and Training of Integrated Visually Impaired Children

Describes experimental work that has been carried out in creating services for integrated visually handicapped children at a Center of assessment, counselling and training, located at a residential school. The principles and methods applied are outlined and a report given of 70 children visiting the Center during one time period. The clinical procedure and follow-up is described. The complexity of the problems and the necessity of an individual approach in habilitation is stressed as well as the importance of team work engaging both professional and nonprofessional persons.

Changes in causes of low vision between 1988 and 2009 in a Dutch population of children

PURPOSE

Causes of low vision in the Netherlands may have changed over time. The purpose of this study is to assess trends over the last two decades.

METHODS

Socio-demographic and medical data, including ophthalmic diagnosis and inheritance patterns for 2843 children with low vision (0-21 years; 50% representation) referred to a Dutch institute for low vision (Bartiméus) over a 21-year period between 1988 and 2009, were included in the analysis. For the 19 most common diagnoses, inheritance and presence of mental impairment, trend analyses were performed with logistic regression models; odds ratios (OR) for a 10-year time span were reported.

RESULTS

Cerebral visual impairment (CVI) was found in 27.2% (97% mental impairment), albinism in 8.0%. Over time, nystagmus (6.6%; OR = 1.42), retinitis pigmentosa (2.9%; OR = 1.61), cone-rod dystrophy (2.6%; OR = 1.98) and hyperopia (2.0%; OR = 3.66) increased significantly. Cataract (4.9%; OR = 0.64), aniridia (1.6%; OR = 0.42) and retinopathy of prematurity (ROP; 2.0%; OR = 0.45) decreased significantly. There was a significant increase in genetic disorders (41.0%; OR = 1.49) and in co-occurrence of mental impairment (52.2% OR = 1.16).

CONCLUSION

In the last two decades, treatable or preventable disorders (such as cataract and ROP) have become a less common cause of low vision in children. However, the prevalence of complex (genetic) and untreatable disorders (CVI) has taken its place, as a result of increased survival of preterm and low birth weight children and improved diagnostic possibilities. Knowledge of the prevalence of low vision, its causes and trends over time may help policy makers to define effective intervention strategies and to monitor its impact.

Visual impairment in Swedish children. III. Diagnoses

PURPOSE

To gain an overview of the spectrum of diagnoses among Swedish visually impaired children.

METHODS

An epidemiological study of all known visually impaired children was made by review of medical records.

RESULTS AND CONCLUSION

In all we found 2373 children, 0-19 years of age, with an age-specific prevalence of 10.9/10,000. The two largest diagnostic groups included neuro-ophthalmological and retinal diseases. The most frequent disorders were cerebral visual impairment, non-hereditary optic atrophy, retinal dystrophy (when regarded as a general entity), congenital hypoplasia of the optic nerve and congenital cataract. Nystagmus secondary to brain disorder, albinism, congenital nystagmus, retinopathy of prematurity and high myopia were also found in a considerable number of patients. The leading diagnoses in children with WHO-defined childhood blindness were non-hereditary optic atrophy, cerebral visual impairment and retinopathy of prematurity. A large proportion of the children, especially in the groups with neuro-ophthalmological disorders and malformations of the posterior segment had additional impairments, emphasizing the importance of a multi-disciplinary approach when assessing multi-handicapped children.

Visual impairment in Swedish children. II. Etiological factors

The analysis of etiological factors in a group of visually impaired children is of considerable importance when trying to find guidelines for possible preventive work. In this study we present etiological data on 2373 Swedish children. Data have been obtained by reviewing medical records on all known children with visual impairment throughout the country. In accordance with similar studies from industrialised countries, the group with prenatal etiology was the predominant, comprising 64% of the material. Within this group, half the patients had a disease of genetic origin. A total of 50% of all patients with prenatal etiology had an additional impairment, but in the group with diseases of genetic origin this proportion was smaller, only 40%. On the other hand, many children with additional impairments were found among those with an unspecified prenatal influence. Peri-/neonatal etiologies were found in 20% of the patients. In this group as many as 83% had additional impairments. This was even more pronounced among children delivered at term. The group with infantile/juvenile etiologies was small, 7%, with additional impairments in 66%. In 9% of all patients the etiology was classified as unknown. Among these, 80% had additional impairments. The visual impairment tended to be more pronounced, the later the disease was acquired. A male preponderance was seen in most etiological subgroups and in the material as a whole.

Visual impairment in Swedish children. I. Register and prevalence data

Knowledge of the epidemiology of visual impairment in children forms one of the cornerstones of pediatric ophthalmology. In contrast to e.g. the other Nordic countries, Sweden has had no efficient and continuous registration of visually impaired children. An epidemiological study on this subject has now been done, collecting data on all children and adolescents registered at the Low Vision Clinics throughout Sweden. In this work data on 2373 visually impaired children, 0-19 years of age and living throughout Sweden are presented. Data collected in the study include sex, date of birth, county, ocular diagnosis, systemic diagnosis, classification of visual impairment, aetiology and possible additional impairments. The prevalence of visual impairment as defined by WHO was 10.9/10,000 inhabitants in the current age group. A slight male preponderance was seen compared to the total population 0-19 years. This was not reduced when only non-genetic aetiological factors were taken into consideration. A total of 45% of the children had only a moderate visual impairment (WHO category 1), whereas approximately 25% were found in WHO categories 3,4 and 5, i.e. fulfilled the requirements for blindness. Additional impairments were found in 60% of the children. Mental impairment in combination with motor impairment or mental impairment exclusively were the most common ones seen.

Visual impairment in Nordic children. III. Diagnoses

The diagnoses, according to type and site and the degree of visual impairment, responsible for severe visual impairment in children below the age of 18, were analyzed in a material compiled from the national registers of visually impaired in Denmark, Finland, Iceland and Norway. Among 2527 children the predominant causes of visual impairment are ascribed to congenital malformations, neuro-ophthalmological diseases and retinal diseases. Optic atrophy is the leading single cause of severe visual impairment when all diagnoses are compared, and this also applies when all categories of visual impairment are included. Retinopathy of prematurity is the second principal cause of severe visual impairment, while cerebral amblyopia rates as the third most significant cause. Congenital cataract is also of considerable importance when all categories of visual impairment are compared. The differences registered between the Nordic countries were found to be within reasonable limits, except for a preponderance of neuro-ophthalmological diseases in the Danish material. This could be explained by a better medical supervision of mentally retarded patients in Denmark. Additional impairments occur in a large percentage of patients, but are unevenly distributed in the disease groups. A high frequency of additional impairments are found in the neuro-ophthalmological group and in the groups with congenital malformations, emphasizing the importance of a multidisciplinary evaluation when dealing with the visually impaired child.

Non-allelism of three genes (rcd1, rcd2 and erd) for early-onset hereditary retinal degeneration

Cross-breeding experiments were utilized to study the genetics of three autosomal recessive, early onset retinal degenerations in dogs. Irish setters affected with rod-cone dysplasia type 1 (rcd1) were bred to Norwegian elkhounds affected with early retinal degeneration (erd). All offspring (15 pups-two litters) surviving to diagnostic age were phenotypically normal, as assessed by electroretinography, retinal morphology and assay of retinal cyclic nucleotide content. One phenotypically normal female Irish setter-Norwegian elkhound crossbred dog (the progeny of the above breeding and thus heterozygous at both the rcd1 and the erd locus) was bred to a collie dog affected with rod-cone dysplasia type 2 (rcd2). All 11 pups from this breeding also proved phenotypically normal by the above methods. These results establish that the genes rcd1, rcd2 and erd are non-allelic. Biochemical data are also presented that establish that erd, unlike rcd1 and rcd2, is not associated with abnormal metabolism of retinal cyclic guanosine monophosphate (cyclic GMP).