Incidence Of Visual Impairment Research Articles

Retrodots in the Lens in the Beaver Dam Eye Study Cohort

To determine the prevalence of retrodots in the lens and the association of these lesions to age-related cataract, and to assess their association with visual impairment and contrast sensitivity. Longitudinal epidemiologic study. The Beaver Dam Eye Study cohort. Eye examinations including grading of standard photographs of the lens and measures of visual function. Statistical associations of retrodots with nuclear, cortical, and posterior subcapsular cataracts and with incident visual impairment and impairment of contrast sensitivity. The prevalence of retrodots at the baseline examination increased with age from 1.68% in those 43 to 54 years of age to 31.20% in those ≥ 75 years of age. After controlling for age, there was no significant difference in the prevalence of retrodots between men and women. The odds ratio (OR) for visual impairment associated with retrodots was 2.22 (95% confidence interval [CI], 1.80-2.75) after controlling for age-related cataracts and other associated characteristics. The association with impaired contrast sensitivity was not significant. Retrodots were not significantly associated with incidence of any type of age-related cataract. The 15-year cumulative incidence of retrodots in right eyes increased with age from 9.3% in those 43 to 54 years of age to 21.1% in those ≥ 75 years of age. In addition to age, incidence of retrodots was independently associated with smoking (OR, 1.27; 95% CI, 1.04-1.56 for ever vs never smoking). Retrodots are frequently occurring age-related lens opacities that are associated with decreased vision independent of the presence of age-related cataract. Their incidence is associated with smoking. Further research to determine the underlying process leading to retrodots is necessary before efforts to develop preventions are undertaken.

Five‐year incidence of visual impairment and blindness in older Icelanders: the Reykjavik Eye Study

This study examined age, sex and cause-specific 5-year incidence of visual impairment and blindness in a middle-aged and elderly Icelandic population. The study cohort consisted of a population-based, random sample of citizens aged > or = 50 years. Of 1379 eligible subjects, 1045 underwent a baseline examination in 1996; 846 of the 958 survivors (88.2%) underwent a 5-year follow-up examination in 2001. All participants underwent an extensive ophthalmological examination including best corrected visual acuity (BCVA) using a Snellen chart. We used World Health Organization (WHO) criteria, which define visual impairment as BCVA in the better eye of < 6/18 and > or = 3/60 and blindness as BCVA in the better eye of < 3/60. We also used US criteria, which consider BCVA of < 6/12 and > 6/60 in the better eye to represent visual impairment and BCVA of < or = 6/60 in the better eye to represent blindness. The causes of incident visual loss in either eye were determined. Deterioration or improvement in vision were defined as a loss or gain of > or = 2 Snellen lines. According to WHO criteria, 5-year incidence of bilateral visual impairment and blindness were 1.07% (95% confidence interval [CI] 0.37-1.76) and 0.35% (95% CI 0.00-0.76), respectively. Using US criteria, equivalent incidence of bilateral visual impairment and blindness were 3.49% (95% CI 2.24-4.74) and 0.95% (95% CI 0.29-1.60), respectively. Age-related macular degeneration and cataract were the major causes of incident visual impairment and blindness. Incidences of visual impairment and blindness increased significantly with age. Age-related macular degeneration, present in 75% of affected persons, was the most common cause of 5-year incident legal blindness in this middle-aged and elderly Icelandic population.

Four-Year Incidence and Progression of Visual Impairment in Latinos: The Los Angeles Latino Eye Study

To determine the 4-year incidence of visual impairment (VI) and blindness and worsening of visual acuity in adult Latinos and Hispanics aged 40 years and older. Population-based, longitudinal study. Participants underwent a detailed ophthalmologic examination including assessing both presenting binocular visual acuity (PVA) and best-corrected distance visual acuity (BCVA) in both eyes using a standard Early Treatment Diabetic Retinopathy protocol. The main outcome measures are 4-year incidence of visual impairment and blindness based on PVA or BCVA in the better-seeing eye and defined as (1) baseline visual acuity (PVA or BCVA) of 20/40 or better and a follow-up PVA or BCVA of less than 20/40 but better than 20/200, and (2) baseline PVA better than 20/200 and a follow-up PVA of 20/200 or less, respectively. Monocular worsening was defined as a decrease of 5 or more, 10, and 15 letters in either eye. Four thousand six hundred fifty-eight participants were examined at baseline and the 4-year follow-up. The 4-year incidence of presenting binocular VI and blindness was 2.9% and 0.3%. The 4-year incidence of best-corrected VI and blindness was 1.2% and 0.3%. The 4-year incidence of monocular worsening by 5 or more, 10, and 15 letters was 24.8%, 8.5%, and 3.1%, respectively. The incidence of VI and blindness increased with age at baseline (P < .01). The incidence of VI in the second eye (12.2%) was significantly higher than the incidence of VI in the first eye (2.9%; P < .001). Overall, the annual incidence of VI in Latinos and Hispanics was higher than that reported in non-Hispanic white persons and the highest reported in a population-based study in the United States. Screening and intervention programs to reduce visual impairment and blindness should focus on the older Latino population.

Effect of visual impairment upon oral health care: a review

The incidence of visual impairment is increasing globally and in the United Kingdom due to local and systemic disease, medical advances, and the increasing age of population groups. Despite there being a large number of people resident in the UK with a visual impairment, there is little information available regarding the dental health care and needs of such individuals. As reported in other groups of patients with special needs, many individuals with a visual impairment may only seek oral health care when a problem arises, such as pain. Visual impairment may have a negative effect upon oral hygiene with many blind and partially sighted individuals having worse oral hygiene than sighted peers. This review article was undertaken to examine the literature relating to visual impairment, oral health and dental care. This article will discuss the dental aspects of visual impairment, its implications for obtaining dental care, associated oral conditions and medical complications.

The changing visual profile of children attending a regional specialist school for the visually impaired in Northern Ireland

To investigate the changing profile of children attending a special school for visually impaired children over a 30-year period. Between 1975 and 2004, 266 children were identified as having been students in the introductory years to secondary education at Jordanstown School. School records and records from the Regional Paediatric Low Vision Clinic at the Royal Victoria Hospital, Belfast were examined to obtain data regarding age, primary ophthalmic diagnosis, visual acuity and any additional impairment. There was no statistically significant change in mean visual acuity of the children entering the secondary school over this period (p > 0.1). Albinism was the most common single condition (20.3%). Notable also was the reduction in incidence of visual impairment following congenital glaucoma and cataract and the corresponding increase in cortical visual impairment (CVI) during this period. During the last 30 years medical/surgical treatment has reduced the impact of treatable conditions (e.g. cataract) on visual impairment to the extent that their prevalence within this school has decreased. Consequently, children with non-treatable conditions (e.g. albinism) constitute a larger proportion of the school population. An increase in the proportion of children with CVI and learning disability in the school was noted.

Vogt-Koyanagi-Harada Disease: Clinical Outcomes

To evaluate the effect of treatment on the incidence of vision impairment and structural ocular complications among patients with Vogt-Koyanagi-Harada (VKH) disease. Retrospective cohort study. setting: Single-center academic practice. study population: Twenty-four consecutive patients with VKH disease who were referred for evaluation and treatment from November 1984 through May 2004. procedures: Information on patients with VKH disease was entered retrospectively into a database and analyzed with time-dependent techniques. main outcome measures: Incidence of visual impairment and of structural ocular complications. In better-seeing eyes, the frequencies of vision loss to 20/50 or worse and to 20/200 or worse at presentation were 50% and 30%, respectively. The incidence rates on follow-up examination for vision loss to 20/50 or worse and to 20/200 or worse were 9% per person-year and 7% per person-year in the better-seeing eye. Oral corticosteroid therapy was associated with a reduced risk of loss of visual acuity to the 20/200 or worse in the better-seeing eye (relative risk [RR] = 0.33; P = .05). The use of immunosuppressive drug therapy was associated with a reduced risk of vision loss to the 20/50 or worse and to the 20/200 or worse thresholds in the better-seeing eye (RR = 0.33; P = .05; and RR = 0.08; P = .04, respectively). VKH disease may result in substantial visual impairment. The use of oral corticosteroid or immunosuppressive drug therapy may reduce the risk of vision loss during the follow-up period.

Inclusion, Impact and Need: Young Children with a Visual Impairment

From preschool to tertiary level, the past decade has witnessed a growing impetus for the inclusion of children with special needs and disabilities in mainstream education. Yet evidence on the needs of children with visual impairments (VI) remains scant. This paper seeks to inform the debate by presenting findings from research designed to explore the perceptions and experiences of parents, young people with VI and health and early years professionals working in the preschool sector. The findings reveal a significant increase in the incidence of VI in children attending early years settings. Despite their commitment to the ideals underpinning inclusive education, interviewees are concerned with the lack of awareness training available for staff working with the VI. Criticism is also levelled at specialist schools in Northern Ireland, for failing to provide a full educational experience for children and young people, aged from three to 18, with VI.

Training and the early years professional: understanding visual impairment

Despite a significant increase in the incidence of visual impairment (VI) in early years children, research has afforded the subject scant attention. Perhaps as a result of underfunding, research into VI typically adopts a single case study approach, with the training needs of early years professionals largely ignored. This paper seeks to inform the debate by presenting empirical evidence from a questionnaire designed to gather data on the incidence of VI in early years settings and the nature and extent of awareness training available. Data from the questionnaire survey and the qualitative dimensions of the study indicate an increase in the incidence of VI and, despite high levels of interest, a paucity of training on issues related to VI. Concern was expressed with delays in diagnosis, the lack of screening available and the extent to which the differing terms used militate against interagency collaboration.

The incidence of visually impaired children with retinopathy of prematurity and their concomitant disabilities.

To determine, in relation to two previous studies, the incidence of visual impairment (VI) caused by retinopathy of prematurity (ROP) in children born in the Netherlands between 1994 and 2000 and their associated nonvisual disabilities. From all institutes, schools, and ambulatory services for the partially sighted and blind, data on ROP infants born between 1994 and 2000 were retrieved. Apart from neonatal and ophthalmologic data, other data were gathered concerning the following concomitant disabilities: behavioral abnormalities, epilepsy, hearing deficit, developmental delay, and distinct neurological handicaps. Birth rate data were obtained from the Central Bureau of Statistics for the Netherlands. Data on 51 of 54 infants (94.4%) were studied. There was a statistically insignificant decrease in the incidence of visually impaired children caused by ROP in the period between 1994 and 2000 compared with the period between 1986 and 1994. Neonatal and ophthalmologic data of the infants were comparable for the study period and the previous period. The incidence of behavioral abnormalities in infants with ROP-related sequelae increased significantly in the study period compared with the previous one (46.9% v 21.8%, P <.05. The percentage of infants who received treatment for severe ROP did not change significantly (56.9% v 43.9% in the previous period). This study shows a statistically insignificant decrease in the number of infants with visual impairment caused by ROP in the Netherlands in the period between 1994 and 2000 as well as a significant increase in the incidence of behavioral abnormalities in these children. Still, 43.1% of the infants did not receive acute-phase ROP treatment.

Risk of vision loss in patients with cytomegalovirus retinitis and the acquired immunodeficiency syndrome.

To characterize the effect of cytomegalovirus (CMV) retinitis and its treatment on visual acuity in patients with the acquired immunodeficiency syndrome. We evaluated 648 consecutive patients with the acquired immunodeficiency syndrome at 1 center for the prevalence of visual impairment at the time of CMV retinitis diagnosis and for the incidence of visual impairment across time. Among affected eyes, the prevalence of a visual acuity measurement of 20/50 or worse or 20/200 or worse at the time of CMV retinitis diagnosis was 33% and 17%, respectively. White race and injection drug use were associated with a lower and a higher prevalence of visual impairment, respectively. At 1 year, the cumulative incidence of loss of 3, 6, and 10 lines of visual acuity was 42%, 30%, and 23%, respectively, and the incidence of visual impairment to the level of 20/50 or worse and 20/200 or worse was 34% and 24%, respectively. Patients who received highly active antiretroviral therapy had an approximately 75% lower risk of visual impairment, with the greatest benefit among those observed to have immune recovery. The incidence of loss of visual acuity did not significantly differ between eyes treated with systemic anti-CMV therapy only, initial ganciclovir implant therapy, or systemic followed by implant therapy. The prevalence of visual impairment at the time of CMV retinitis diagnosis is high and varies according to demographic characteristics. The incidence of visual impairment during follow-up is also high but is substantially lower among patients who receive highly active antiretroviral therapy, especially those observed to have immune recovery.

Incidence of blindness and low vision in a sample population: The Priverno Eye Study, Italy

Purpose To study the incidence of blindness and low vision over a 7-year period. Design Population-based cohort study. Participants The survivors of the original cohort of 860 persons from Priverno, Italy, aged 45 to 69 years, were reexamined. Of the 760 eligible survivors, 619 (81.4%) had a 7-year follow-up visit. Methods Baseline and follow-up examinations included the collection of anamnestic and ophthalmologic data by the same observers using the same methods and classification criteria to minimize sources of variability. Main outcome measures Best-corrected visual acuity (VA) measured at 4 m by standardized logarithmic chart was expressed as the logarithm of the minimum angle of resolution (logMAR). World Health Organization definitions of blindness and low vision were adopted (respectively, VA > 1.3 logMar and VA > 0.6 to 1.3 logMar in the better eye or in either eye). Participants at risk for visual impairment were those without blindness or low vision in one or both eyes at baseline; participants at risk for one-eye visual impairment were those without blindness or low vision in both eyes at baseline. Results A total of 33 participants were defined as incident cases of visual impairment. The overall incidence figures for blindness, low vision, one-eye blindness, and one-eye low vision were respectively 0.2% (95% confidence interval [CI], 0.0–0.9), 1.3% (95% CI, 0.7–2.6), 1.2% (95% CI, 0.6–2.4), and 2.9% (95% CI, 1.8–4.6). Conclusions This study provides population-based estimates of the incidence of visual impairment in an adult, free-living European population. With respect to the younger participants, older subjects at baseline were at higher risk for incident visual impairment, the main causes of which were cataract, myopia, and diabetic retinopathy. The incidence of visual impairment in the subgroup aged 55 to 64 years at baseline was significantly higher than that found in Beaver Dam 5-year study and similar to that found in Beaver Dam 10-year Study, when the same definitions were adopted. This difference may be partially explained by social and cultural habits of the female samples, but many other factors may play a role.

The prevalence and incidence of visual impairment in people of age 20–59 years in industrialized countries: A review

BACKGROUND Reviews on the prevalence of blindness and low vision in persons of age 20 to 59 years are lacking. We have therefore carried out a review based on a Medline search. METHODS The review was confined to epidemiological studies performed in Western Europe, North America and Australia covering the age group 20 to 59 years where there were comparable definitions of blindness and low vision according to the IAPB and WHO classification of blindness and low vision. RESULTS Three surveys, four register studies and two studies based on multiple sources matched our selection criteria. Blindness and low vision are described separately. Blindness Only one study, based on multiple sources, covered the whole age group 20 to 59 years. In this study the overall prevalence of blindness was 0.08%. The prevalence of blindness was 0.04% among those 20–39 years old, whereas in the age group 40–59 years it was 0.1% in two surveys and one study on multiple sources. However, the prevalence was higher, 0.5% among whites and 0.7% among colored, in The Baltimore Eye Study. The definition of blindness was similar in all three studies. Low vision Three studies provided data on the prevalence of low vision in the age group 20–59 years, although the number of cases was very small. In one study the prevalence of a visual acuity =6/24 to 6/48 was 0.07% and in another the prevalence was 0.17% using <6/18 to 0.5/60. No person with low vision was found in the third study. CONCLUSIONS The existing epidemiological data on blindness and low vision among adults aged 20 to 59 years are insufficient. Epidemiological studies based on multiple sources are needed for the study of rare conditions such as blindness and low vision.

Five-year change in visual acuity and incidence of visual impairment: the Blue Mountains Eye Study

Purpose To describe the 5-year change in visual acuity and the incidence of visual impairment in a population-based cohort. Design Population-based epidemiologic study. Participants Of the 3654 participants of the Blue Mountains Eye Study (BMES I) baseline examination (aged 49 years+ during 1992–1994), 2335 were reexamined during the 5-year follow-up examinations from 1997 to 1999 (BMES II), and 543 persons had died since BMES I. Methods Visual acuity was measured using a logarithm of the minimum angle of resolution chart in both eyes separately before and after standardized refraction. Pupils were dilated and a detailed examination was performed. Main outcome measures Visual impairment, after best refractive correction, was defined as any (visual acuity ≤20/40; ≤41 letters) and severe (visual acuity ≤20/200; 0–5 letters) in keeping with the Beaver Dam Eye Study. Incident binocular visual impairment was defined as visual acuity ≤20/40 in both eyes at follow-up, where visual acuity was >20/40 in both eyes at baseline. Incident binocular severe visual impairment was defined as visual acuity ≤20/200 in both eyes at follow-up, where visual acuity was >20/200 in both eyes at baseline. The incidence for three other levels of visual impairment is also given: <20/40, <20/70, and <20/200. Monocular visual impairment was defined as impairment in one eye only at follow-up, where both eyes were unimpaired at baseline. Incident doubling and halving of the visual angle were calculated. Results Incidence rates for visual impairment increased significantly with age. Any incident impairment ≤20/40 occurred binocularly in 41 persons (1.9%) and monocularly in 150 persons (7.1%). Severe incident impairment ≤20/200 occurred binocularly in 3 persons (0.1%) and monocularly in 44 persons (2.1%). Incident impairment <20/40 occurred binocularly in 37 persons (1.7%) and monocularly in 134 persons (6.3%). Impairment <20/70 occurred binocularly in 15 persons (0.7%) and monocularly in 84 persons (3.8%). Impairment <20/200 occurred binocularly in 3 persons (0.1%) and monocularly in 44 persons (1.9%). Women consistently had a higher incidence of visual impairment than men, although this was often not statistically significant after adjusting for age. Increasing age was a strong predictor of visual impairment. Conclusions This study has documented the 5-year incidence and causes of visual impairment in an older Australian population.

Causes of incident visual impairment: the Blue Mountains Eye Study.

To describe the causes of 5-year incident visual impairment and doubling of the visual angle in a population-based cohort. Of the 3654 participants aged older than 50 years who participated in the Blue Mountains Eye Study (BMES I, 1992-1994), 543 died and 2335 were reexamined between 1997 and 1999 (BMES II). Visual acuity was measured using a logMAR chart before and after refraction. Pupils were dilated, and a detailed eye examination was performed. For participants with incident visual impairment or doubling of the visual angle, an ophthalmologist attributed and proportioned causes. Primary causes were defined as those responsible for 50% or more of the impairment. After refractive correction, the proportion of incident bilateral impairment worse than 20/40, worse than 20/70, and worse than 20/200 that were caused primarily by cataract decreased from 51.4% (n = 19) to 40.0% (n = 6) to 0%; while the proportion of cases caused primarily by age-related maculopathy increased from 24.3% (n = 9) to 33.3% (n = 5) to 100.0% (n = 2). Similarly, the corresponding proportions of incident unilateral impairment caused primarily by cataract decreased from 53.7% (n = 72) to 36.9% (n = 31) to 13.6% (n = 6); meanwhile, the proportion of cases caused primarily by age-related maculopathy increased from 19.4% (n = 26) to 32.1% (n = 27) to 54.5% (n = 24). The proportions of persons with incident bilateral impairment worse than 20/40, worse than 20/70, and worse than 20/200 that could be improved with refraction were 79.4% (n = 143), 73.6% (n = 42), and 0%, respectively. The corresponding proportions of incident unilateral impairment improved by refraction were 66.7% (n = 269), 59.0% (n = 121), and 21.4% (n = 12). This study has documented the 5-year incidence and causes of visual impairment in an older Australian population.

Changes in visual acuity in a population over a 10-year period : The Beaver Dam eye study

Purpose To describe the change in visual acuity in a 10-year period. Design Population-based cohort study. Participants Included 3684 persons 43 to 86 years of age at the time of a baseline examination in 1988 to 1990, living in Beaver Dam, Wisconsin, at a follow-up examination in 1993 to 1995 and/or 1998 to 2000. Methods Best-corrected visual acuity was measured, after refraction, with logarithm of the minimum angle of resolution charts using a modification of the Early Treatment Diabetic Retinopathy Study protocol. Main outcomes measures Doubling of the visual angle and incidence of visual impairment. Results The change in the mean number of letters read correctly over the 10-year period varied in the right eye from −0.9 (standard deviation [SD] = 5.5) and in the left eye from −1.2 (SD = 6.6) in people between 43 and 54 years of age to −11.0 (SD = 20.0) in the right eye and −12.6 (SD = 20.4) in the left eye in people 75 years of age or older (n = 184) at baseline. Over the 10-year period, 5.9% of the population had impaired vision (20/40 or worse in the better eye) develop, 0.8% had severe visual impairment (20/200 or worse in the better eye) develop, 4.8% had doubling of the visual angle, and 3.9% had improved vision. People who were 75 years of age or older at baseline were 15.0 times (95% confidence interval [CI], 10.9–20.6; P < 0.001) as likely to have impaired vision develop, 9.3 times (95% CI, 6.5–13.3; P < 0.001) as likely to have doubling of the visual angle, and 19.8 times as likely (95% CI, 8.4–46.4; P ≤ 0.001) to have severe visual impairment develop than people younger than 75 years of age at baseline. For the 82 persons 75 years of age or older, currently residing in a nursing or group home at follow-up, they were 2.6 times (95% CI, 1.45–4.52) as likely to have impaired vision develop, 1.6 times (95% CI, 0.47–5.62) as likely to have severely impaired vision develop, and 3.6 times (95% CI, 1.96–6.78) as likely to have had a doubling of the visual angle than those not residing in a nursing or group home at follow-up. Conclusions These data provide precise population-based estimates of the 10-year incidence of loss of vision over a wide spectrum of ages and show that decreased visual acuity in people 75 years of age after 10 years is a common finding, especially in those who are admitted to nursing or group homes.

The incidence of visual impairment and its determinants in the WHO Multinational Study of Vascular Disease in Diabetes.

Incidence of severe visual impairment and the ultimate prevalence of all grades of impairment were estimated in the 10 centres of the WHO Multinational Study of Vascular Disease in Diabetes (WHO MSVDD) participating in the follow-up. Visual function was ascertained at follow-up in 2994 (77.9 %) of the 3845 eligible participating survivors of the 4709 originally recruited for the WHO MSVDD using the same baseline enquiry method. The associations between incident severe visual impairment, follow-up prevalence of all grades of impairment and baseline risk factors were examined by univariate and stepwise multiple logistic regression analysis. Overall, 8.4 year incidence of severe visual impairment was 1.94 % and showed statistically significant univariate correlations with age at diagnosis, diabetes duration, systolic blood pressure, fasting blood glucose and cholesterol, insulin treatment and strongly with baseline retinopathy. Baseline retinopathy, systolic pressure and cholesterol were statistically significant in multivariable analysis. Differences between centres (0.3% to 3.45%) were not significant. Ultimate prevalence of all grades of impairment differed between centres and within almost all of them was correlated in multivariable analysis with baseline retinopathy and proteinuria. Comparisons of incident severe visual impairment between centres are restricted by selective mortality, low incidence rates and relatively small numbers in each centre but before retinopathy, baseline systolic pressure and cholesterol predicted severe visual impairment. Follow-up prevalence of all degrees of impairment varied among centres and were associated with prior retinopathy and renal disease at baseline.

Visual impairment in children with acute nontraumatic coma.

To determine the incidence and severity of visual impairment in children following acute nontraumatic coma. An 18-month prospective epidemiologic study of acute nontraumatic coma was undertaken in the former Northern NHS Region of England. Children aged >1 month and <16 years were included in the study if they had a Glasgow Coma Score of < or = 12 for >6 hours or if they died within 6 hours of the onset of decreased levels of consciousness. For survivors, ophthalmologic assessments were performed 6 weeks and 12 months after presentation. Two hundred eighty-seven children were included in the study, of whom 127 died. Of the 137 examined survivors, 35 had visual abnormalities suspected by the examining neurologist during the ophthalmic assessment. Of these, visual impairment was confirmed in 10 children at the 6-week assessment by the pediatric ophthalmologist. At the 1 2-month assessment, visual impairment remained stable in 9 children and improved in 1. In this study, 6.6% of children surviving acute nontraumatic coma had visual impairment that persisted at the 12-month follow-up examination. Incidence of visual impairment in acute nontraumatic coma is 0.97 per 100,000 children per year.

Incidence of registered visual impairment in the Nordic child population.

A collaborative, population based, prospective register study on the incidence of visual impairment in children during the year 1993 was carried out in five Nordic countries with a total population of 17 million inhabitants. The child population was 3.8 million individuals aged 0-17 years. The following variables were taken into account: nationality, age, sex, diagnoses, aetiology, degree of visual impairment, and additional impairments. Classification routines from an earlier prevalence study were used. The present study included 304 children corresponding to an incidence of notification of 8/100,000 children, varying from 5.7 to 11.1 in the five countries. Fifty per cent of the visually impaired children were reported before they were 3 years of age. In approximately 45% of the children, visual impairment was due to various brain disorders, with cerebral amblyopia and secondary optic atrophy as the two leading causes. The relative impact of retinopathy of prematurity had decreased from the third most frequent cause (10%) in the prevalence study to seventh place (4%) in the incidence study. Two thirds of the children had additional impairments and these children also suffered from the most severe visual impairments. Among aetiological factors the majority (64%) were prenatal. The overall male:female ratio of 1.4:1 was identical to the sex ratio of the prevalence study.

Heredity and Age-Related Macular Degeneration

To determine the concordance of age-related macular degenerative changes in monozygotic twins. Between 1984 and 1993, we examined a total of nine pairs of monozygotic twins with substantial age-related macular degenerative changes in at least one member of the pair, ranging from extensive large drusen to advanced atrophic and/or disciform scarring. Eight pairs were female and one pair was male. Ages ranged from 62 to 88 years. Monozygosity was confirmed by genetic testing in each of the seven twin pairs on whom it was performed. In eight of the nine twin pairs, the fundus appearance and the incidence of visual impairment were similar. In the ninth pair, one twin had advanced exudative age-related macular degeneration with vision loss in one eye, while the other had large, confluent drusen and good visual function in both eyes. Environmental factor, including diet, geographic background, and medical history, were essentially similar in the twin pairs. Although selection factors and similar environmental influences might impact our findings, the markedly similar incidence of macular degenerative changes in these monozygotic twins suggests that a substantial genetic component may exist in a potentially large proportion of patients with age-related macular degeneration. Further studies are warranted to define this hereditary influence.

Risk of visual impairment attributable to ocular histoplasmosis. Washington County Follow-up Eye Study Group.

To compare 15-year incidence rates of visual impairment and vision-threatening conditions between cases with ocular histoplasmosis and controls residing in the same endemic community. Controls and cases with and without disciform lesions who were between 30 and 69 years of age when selected, interviewed, and examined in 1970 were reinterviewed and reexamined in 1985. Of the 252 cases and controls examined in 1970, 216 were still alive in 1985. Of these, 202 (94%) were interviewed; 197 (91%) underwent visual acuity measurement; and 173 (80%) were examined by a study ophthalmologist. Both in 1970 and in 1985, cases with disciform macular lesions of ocular histoplasmosis had a higher prevalence of both unilateral and bilateral visual impairment and blindness. Although prevalence of visual impairment and blindness in 1985 was similar among controls and cases of ocular histoplasmosis without disciform lesions, this group of cases had about twice the incidence of visual impairment as that of controls. However, the 95% confidence intervals on estimates of relative risks were broad and included unity. No new disciform lesions attributable to ocular histoplasmosis were found in 28 eyes of 18 cases free of them in 1970 or among 148 controls. The 15-year risk of visual impairment and blindness appears to be somewhat higher among adults aged 30 years and older who have only peripheral atrophic scars characteristic of ocular histoplasmosis than among individuals without such scars who live in the same endemic community. Adults who already have a disciform lesion attributed to ocular histoplasmosis in one eye are at low risk of development of a disciform lesion in the fellow eye later in life.