Jugnoo S Rahi

Risk, causes, and outcomes of visual impairment after loss of vision in the non-amblyopic eye: a population-based study.

BACKGROUND Screening for amblyopia in early childhood is done in many countries to ensure that affected children are detected and treated within the critical period, and achieve a level of vision in their amblyopic eye that would be useful should they lose vision in their non-amblyopic eye later in life. We aimed to investigate the risk, causes, and outcomes of visual impairment attributable to loss of vision in the non-amblyopic eye. METHODS For 24 months from July, 1997, national surveillance was done to identify all individuals in the UK with unilateral amblyopia (acuity worse than 6/12) who had newly acquired vision loss in the non-amblyopic eye, resulting in acuity of worse than 6/12 or visual-field restriction precluding driving. Information about participants was obtained at presentation and 1 year later. Participants were categorised as having socially significant visual impairment, or visual impairment, severe visual impairment, or blindness, in accordance with WHO taxonomy. FINDINGS Of 370 eligible individuals, at presentation 104 (28%) had socially significant visual impairment, 180 (49%) visual impairment, and 86 (23%) severe visual impairment or blindness. The minimum risk of permanent visual impairment by age 95 years was 32.9 (95% CI 29.1-36.9) per 100,000 total population. The projected lifetime risk of vision loss for an individual with amblyopia was at least 1.2% (95% CI 1.1-1.4). Only 36 (35%) of 102 people previously in paid employment were able to continue. INTERPRETATION In the UK, where screening for amblyopia is under review, risk of serious vision loss affecting the non-amblyopic eye and its results are greater than that previously assumed. Thus, in addition to the benefits of improved vision in the amblyopic eye, treatment of amblyopia during childhood is a potentially valuable strategy to prevent incapacitating vision loss later in life.

Severe visual impairment and blindness in children in the UK

BACKGROUND Prevention of visual impairment and blindness in childhood is an international priority. However, many countries do not have contemporary information about incidence and causes, from which the scope and priorities for prevention and treatment can be identified. METHODS In the UK, children aged younger than 16 years newly diagnosed with severe visual impairment or blindness (SVI/BL, WHO criteria) during 2000 were identified through national active surveillance schemes in ophthalmology and paediatrics. From these data, we calculated yearly age-group specific incidence and cumulative incidence. Causes were classified by the anatomical site or sites affected and by timing of the insult or insults and causal factors, where known. FINDINGS Of 439 newly diagnosed children, 336 (77%) had additional non-ophthalmic disorders or impairments (SVI/BL plus). Total yearly incidence was highest in the first year of life, being 4.0 (95% CI 3.6-4.5) per 10000, with a cumulative incidence by 16 years of age of 5.9 (5.3-6.5) per 10000. 10% (44) of all children died within 1 year of diagnosis of blindness. Prenatal causal factors affected 61% (268) of children, with perinatal or neonatal and childhood factors each affecting 18% (77). Incidence and causes varied with presence of non-ophthalmic impairments or disorders, birthweight, and ethnic origin. At least 75% (331) of children had disorders that were neither potentially preventable nor treatable, with current knowledge. INTERPRETATION Severe visual impairment and blindness in childhood in the UK is more common, occurs more frequently in the context of complex non-ophthalmic impairments, and has greater associated mortality, than previously assumed. An increased rate in children of low birthweight and from ethnic minority groups, together with the observed diversity and complexity of the causes, reflect recent secular changes in the population at risk, specific risk factors, and strategies available for treatment.

Prediction of improved vision in the amblyopic eye after visual loss in the non-amblyopic eye

Amblyopia arises from abnormal visual experiences in early childhood. Improved function of the amblyopic eye after visual loss in the non-amblyopic eye could be a model for residual neural plasticity. We aimed to establish the likelihood of, and predictive factors for, this improvement in function. We identified 254 individuals aged 11 years or older with unilateral amblyopia who were visually impaired after loss of vision in their non-amblyopic eye but had no other disorder affecting their amblyopic eye. 25 (10%) of 254 people had improved visual acuity in their amblyopic eye. These findings suggest there is some plasticity in the visual system of a few visually mature individuals with amblyopia, which warrants further study. Children should remain the focus of detection and treatment.

Does amblyopia affect educational, health, and social outcomes? Findings from 1958 British birth cohort

Abstract Objective To determine any association of amblyopia with diverse educational, health, and social outcomes in order to inform current debate about population screening for this condition. Design, setting, and participants Comparison of 8432 people with normal vision in each eye with 429 (4.8%) people with amblyopia (childhood unilateral reduced acuity when tested with correction and unaccounted for by eye disease) from the 1958 British birth cohort, with respect to subsequent health and social functioning. Results No functionally or clinically significant differences existed between people with and without amblyopia in educational outcomes, behavioural difficulties or social maladjustment, participation in social activities, unintended injuries (school, workplace, or road traffic accidents as driver), general or mental health and mortality, paid employment, or occupation based social class trajectories. Conclusions It may be difficult to distinguish, at population level, between the lives of people with amblyopia and those without, in terms of several important outcomes. A pressing need exists for further concerted research on what it means to have amblyopia and, specifically, how this varies with severity and how it changes with treatment, so that screening programmes can best serve those who have the most to gain from early identification.

Regional variation in blindness in children due to microphthalmos, anophthalmos and coloboma

BACKGROUND. The prevalence and causes of blindness in children vary widely between regions. Few epidemiological data are available on the relative importance of the major congenital anomalies of the globe (i.e., microphthalmos, anophthalmos, coloboma) as causes of blindness in children. The aim of this study was to determine the re-gional variation in the proportion of severe visual impairment and blindness due to congenital abnormalities of the globe in children in schools for the blind and in those identified through Community Based Rehabilitation programs. Other objectives were to estimate the prevalence of blindness due to major congenital abnormalities, and to investigate their etiology. METHODS. Data on the causes of blindness in children were collected between 1990 and 1998 using standard methods, definitions and reporting form in 26 countries. Children were examined in schools for the blind and in Community Based Rehabilitation programs. RESULTS. Of 7,113 children aged 3-15 years with severe visual impairment and blindness examined, 762 (10.7%) had microphthalmos, 161 (2.3%) had anophthalmos, and 96 (1.3%) had coloboma. There are large regional differences in the proportion of severe visual loss in blind school children, ranging from 1.4% in Cuba to 33.2% in Sri Lanka. Severe visual loss due to congenital abnormalities of the globe is estimated to affect between 0.4 and 16.2/100,000 children in the countries studied. An underlying cause could not be identified in 84.2%. CONCLUSIONS. Major congenital abnormalities of the globe are important causes of severe visual loss in children, particularly in Asian countries. Further research into etiology is warranted in order to plan prevention programs.

Inferring myopia over the lifecourse from uncorrected distance visual acuity in childhood

Aim: To report the usefulness of uncorrected distance visual acuity (DVA) at 16 years to “screen” for myopia status and to assess the lifetime risk of myopia, based on a national birth cohort. Methods: 1867 members of the 1958 British birth cohort for whom there were data on acuity at 16 years had autorefraction, as part of a biomedical survey, at 45 years. Reduced uncorrected DVA at age 16 years (6/12 or worse in both eyes) was compared with adult refraction (spherical equivalent). Results: Only a quarter of individuals in the population studied who had developed myopia by 45 years of age had reduced acuity at 16 years of age. Notably, half of all adults with moderate myopia (−2.99 to −5.99) and 31% (11/35) with severe myopia (⩾−6) had good uncorrected DVA in both eyes at 16 years of age. Thus, sensitivities were low, ranging from 16% for all myopia (cut-off point spherical equivalent −0.5) to 69% for severe myopia (cut-off point spherical equivalent −6). However, a high (91%) lifetime probability of primary myopia (spherical equivalent ⩾−0.5) given a reduced uncorrected DVA at 16 years was found. Conclusion: In this population, reduced uncorrected DVA in childhood is an inaccurate and inappropriate intermediate “phenotype” for capturing adult myopia status. However, our findings support assessment of DVA in secondary school children as an effective method of identifying refractive error (both myopia and hypermetropia).

Blindness certification of children 1 year after diagnosis: findings from the British Childhood Vision Impairment Study

Established in Britain in the 19th century, the sight impairment register has been the sole means of routinely monitoring the frequency and causes of visual impairment in children to plan services and prioritise research.1 Although not a prerequisite, certification and consequent registration is often the catalyst for statutory assessment of special educational needs. It is also often the portal for accessing social services.2 Certification remains voluntary in the UK, by contrast with similar registers elsewhere. However, considerable effort has recently been directed to addressing previous concerns about incomplete reporting of information and underascertainment of eligible individuals.1 2 We have previously reported incidence and causes of severe visual impairment (SVI) or blindness (BL) and associated mortality3 in a nationally representative group of children with SVI/BL in the UK. We now report on the BL certification status of these children 1 year after diagnosis. Active surveillance was undertaken, simultaneously but independently, through the British Ophthalmological4 and British Paediatric5 Surveillance Units, whose reporting bases comprise all consultant ophthalmologists and paediatricians, respectively, in the UK. Every month for 1 year (2000), clinicians reported all children aged <16 years who were newly diagnosed as having SVI/BL due to any disorder. Children were eligible if they had a corrected distance visual acuity of worse than LogMAR 1.0 (Snellen 6/60 or equivalent) in the better eye, that is, SVI/BL using the WHO international taxonomy.6 Children were also considered eligible if their acuity could not be measured formally but they had clinical features …

Uncorrected refractive error and education

A global problem requiring more research measuring outcomes that matter to children and their parents