Rate Of Blindness Research Articles

Ten-year Incidence of Visual Loss in a Diabetic Population

The purposes of this study are to estimate the 10-year incidence of blindness and visual loss in a diabetic population, examine risk factors for visual loss, and examine temporal trends in rates of blindness and visual loss. The design is a population-based cohort study, which includes 891 younger-onset persons with diabetes, 485 persons with older-onset diabetes who are taking insulin, and 502 persons with older-onset diabetes who are not taking insulin and who participated in baseline, 4-year, and 10-year examinations. The main outcome measures are incidence of blindness (visual acuity, 20/200 or worse), doubling of the visual angle, and visual impairment (visual acuity, 20/40 or worse). The 10-year incidences of blindness were 1.8%, 4.0%, and 4.8% in persons in the younger-onset, older-onset taking insulin, and older-onset not taking insulin groups, respectively. Respective 10-year rates of visual impairment were 9.4%, 37.2%, and 23.9%. Rates for doubling of the visual angle were similar. Doubling of the visual angle was more common in women with older-onset diabetes and in persons with younger-onset and older-onset diabetes who were taking insulin and who had higher glycosylated hemoglobin or proteinuria levels. The presence of macular edema or more severe retinopathy was associated with more visual loss in all three groups. Smoking was associated with visual loss in persons with younger-onset diabetes, and systolic blood pressure was associated in persons with older-onset diabetes who were taking insulin. Rates of blindness and doubling of the visual angle decreased in persons with younger-onset diabetes in the second part of the follow-up. In the older-onset groups, only the rate of blindness declined. These decreases could not be explained entirely by treatment or mortality. Several modifiable risk factors are associated with loss of vision. Although visual loss is still common in this diabetic population, the incidence of blindness may be decreasing.

Retinopathy of prematurity in Frederiksborg County 1988-1990. A prospective investigation, an update.

A report is given of retinopathy of prematurity findings in a Danish county (pop. 342,000) for birth years 1988-90. Out of 12,116 liveborn infants 200 were followed with eye controls during (at least) the first 3 months. In 135 gestational age and/or birth weight were below 32 weeks/1750 g. Twenty-five had ROP stage 1-2 with uneventful regression. Out of 5 with at least stage 3 ROP 2 had spontaneous regression. Three had cryotherapy; two acquired unilateral blindness, one myopia of prematurity. As part of an ongoing prospective investigation the visual results denote progress as compared to the serious results from the preceding 6 years (6 blind children). For 1982-90 the pooled ROP blindness rate amounted to 18.7/100,000 liveborn, a frequency only to be surpassed by the neighbouring Copenhagen area. Considering correct timing of cryotherapy close observation of small premature infants is recommended. At present our screening limits are 32 weeks gestational age/1750 g birth weight.

Eye lesions, blindness and visual impairment in the Taraba river valley, Nigeria and their relation to onchocercal microfilariae in skin

2876 persons in fourteen communities in the Taraba River Valley, Nigeria were examined for eye lesions and tested for visual acuity using the ‘tumbling E’. The individuals were also examined for microfilaria of Onchocerca volvulus. More than one-tenth of the population were blind, while another 16.1% had visual impairment. The prevalence of blindness was in excess of 20% in six communities, with one community recording 71.9% blindness rate. All forms of visual involvement increased with age but were similar between sexes. Eye lesions were related to the level of vision. Both eye lesions and vision deteriorate with increase in age. Vision seems to worsen with increase in prevalence and intensity of O. volvulus. Large microfilarial loads were associated with severe eye damage and blindness. These findings indicate that the Taraba river valley could be one of West Africa's worst foci of onchocercal blindness.

The Differential Burden of Blindness in the United States

IN a series of papers from the Baltimore Eye Survey, Sommer and colleagues have confirmed that the leading causes of blindness in the United States are cataract, primary open-angle glaucoma, and age-related macular degeneration.1 2 3 4 5 The results show differences in the race-specific rates of blindness that raise fundamental questions about the U.S. system of medical eye care and its availability to black Americans. In their population-based survey, age-adjusted rates of bilateral blindness were 1.75 percent among blacks and 0.76 percent among whites.2 In a study in this issue of the Journal, Sommer et al. report that among those under the . . .

A community trial of ivermectin for onchocerciasis in Sierra Leone: clinical and parasitological responses to the initial dose

A double-blind placebo-controlled trial of ivermectin was started in 1987 in 6 villages in southern Sierra Leone. 1625 villagers, 93% of the total population, were surveyed before treatment and allocated at random to the trial. Onchocerciasis was hyperendemic and of moderate intensity in the area. Typical onchocerciasis skin lesions were seen in most cases; the blindness rate was 1.5% and a further 4.3% had visual impairment. Six months after treatment 988 subjects (80%) were reassessed and microfilarial loads in the ivermectin group were found to be 10% of control levels. Additionally, blood eosinophil concentrations were reduced by one-quarter. The severity, but not the prevalence, of skin lesions was significantly reduced in the ivermectin group, with a particularly marked effect on papular eruptions. There had been no reduction in the prevalence of itching, nor had markers of general health shown improvement after ivermectin. Ivermectin is an effective microfilaricidal agent and may improve Onchocerca-related skin lesions after a single dose. However, the lack of obvious benefit to a target population after the first dose of ivermectin may reduce compliance with subsequent doses. This has implications for planned mass treatment initiatives in onchocerciasis endemic regions.

Ocular Problems in Older Americans with Diabetes

Data from the Wisconsin Epidemiologic Study of Diabetic Retinopathy from persons with diabetes of older onset whose average age was 65.4 years indicate that 9.9% of the men and 13.3% of the women had some degree of visual impairment, and 1.4% of men and 1.7% of women were legally blind (with an visual acuity of 20/200 or worse in the better eye). Poorer visual acuity was strongly associated with increasing duration of diabetes, but age was also an important factor, with rates of legal blindness increasing markedly after the seventh decade of life in groups of any duration. Conditions responsible for legal blindness were diabetic retinopathy or maculopathy, cataracts, glaucoma, and macular degeneration. Incidence of blindness 4 years after the initial evaluation was related to insulin use, younger age at examination, longer duration of diabetes, and more severe retinopathy at baseline. Worsening of vision was related to higher levels of glycosylated hemoglobin and the presence of macular edema on diabetic retinopathy at baseline. These data indicate that there is a high prevalence of ocular problems among people with diabetes of older onset. The practitioner should suggest to these patients that, soon after the diagnosis of diabetes, they have an ophthalmologic evaluation to determine whether asymptomatic problems are present. This action may lead to timely intervention to prevent loss of vision in some patients.

Blacks at Greater Risk for Blindness

To the Editor. —Preventable blindness is and should be a major concern for all opthalmologists. The recent report of the Baltimore (Md) Eye Survey by Tielsch et al 1 in the February 1990 issue of theArchivesshould be required reading not only for all ophthalmologists, but for all family-practice physicians and other providers of primary health care because of the compelling public health implications of their findings. The authors report the finding of a prevalence rate of blindness among blacks that is double the rate among whites. In 1979, I reported identical findings based on analysis of model reporting area (MRA) data. 2 In addition, I found that blacks were eight times more likely to be blinded due to glaucoma than whites (Figure and Table). Comparatively, the MRA data in Table 4 1 show a lower prevalence of blindness among blacks (ie, 1.20% in the age group 65 to

Blindness and Visual Impairment in an American Urban Population

To the Editor. —I congratulate Dr Tielsch and coworkers in the Baltimore Eye Survey Research Group 1 for their article in the February 1990 issue of theArchivesI hope that in the tremendous amount of data that they accumulated about the population they investigated, they secured information on income. It would be unfortunate if they did not. As is well known, income is directly related to accessibility to medical care. In the people whose blindness is preventable, accessibility to medical care is a key factor. It would be most interesting and important to compare blindness rates in low-income black patients with those in low-income white patients and to compare both groups with middle- and high-income blacks and whites. I look forward to future publications by this group.

A 12‐year experience of retinopathy of prematurity in infants ≤28 weeks gestation or ≤1000g birthweight

This study reported the prevalence and severity of retinopathy of prematurity (ROP) in less than or equal to 28 weeks gestation or less than or equal to 1000 g birthweight infants over a 12-year period. Among 328 survivors of less than or equal to 28 weeks gestation, 30% had ROP, 12% had severe ROP of Stage 3 or worse, 5% had at least one blind eye and 3% were bilaterally blind. Among 201 survivors of less than or equal to 1000 g birthweight, the above abnormalities were found in 40, 16, 6 and 4% respectively. In both cohorts there was a significant increase in the prevalence of ROP and severe ROP between the period 1977-80 and 1981-84, but the lesser increase observed between the periods 1981-84 and 1985-88 was not statistically significant. The rates of ROP-induced blindness were not significantly different between the three 4-year periods. An inverse relationship was noted between the prevalence of ROP and gestational age. The results suggest a resurgence of ROP in less than or equal to 28 weeks or less than or equal to 1000 g infants, the cause of which is uncertain. In view of this trend, continued surveillance of ROP is warranted.

Visual impairment of age‐related macular degeneration

To emphasize the unknown visual impairment of age-related macular degeneration (AMD)-defined as macular changes causing a visual acuity of 6/9 or less-an epidemiological study was designed including 1000 age stratified and randomly selected Danes, 60-80 years of age. Among the 924 individuals in whom both maculae could be examined (1848 eyes) a total number of 173 AMD eyes was found in 112 persons. For all AMD eyes, the composition of visual loss can be described as an iceberg with minor visual impairment of 6/9-6/12 as the predominant base (71.7%), partial impairment of 6/18-6/36 as an interjacent area (15.0%) and major impairment of 6/60 or less (i.e. blindness) as the top (13.3%). By use of a logistric regression model the proportion of exudative macular degeneration among all AMD eyes (atrophic + exudative) was demonstrated to be significantly increasing with decreasing visual acuity but unrelated to age. The prevalence rates of AMD were age related in each of the visual subgroups of minor, partial and major impaired eyes. The prevalence rates of social blindness (6/60 or less in both eyes) due to AMD are estimated to be 4.3 per 1000 persons and of monocular blindness 16.2 per 1000. Further calculations suggest that about 90,000 out of 870,000 Danes. 60-80 years old, have visual impairment of 6/9 or less caused by AMD in one or both eyes.

Community-based eye health survey in areas of Buan-Kun and Dobong-Ku in Korea

This survey comparing the primary causes of eye disease and visual impairment between rural and urban areas was conducted from the beginning of February through May of 1989. The outcome of that research on 686 residents (1372 eyes) of Buan-Kun, Chunbuk, and 997 residents (1994 eyes) of Dobong-Ku, Seoul, is as follows: 1. Of the basic ocular affections, pterygium was the most prevalent in Baun-Kun with 178 eyes (13.0%), while allergic and chronic conjunctivitis were in the majority in Dobong-Ku with 170 eyes (8.5%). 2. In causes of visual impairment, refractive error showed to be the main one in both Buan-Kun with 135 eyes (9.8%) and Dobong-Ku with 132 eyes (6.6%). 3. In rate of blindness, Buan-Kun had 7.0% monocular blindness and 3.2% of binocular blindness, while 4.1% of monocular blindness and 1.7% of binocular blindness were found in Dobong-Ku. 4. In causes of blindness, cataract (51.1%) was followed by macular degeneration (17.4%), corneal opacity (13.0%), and vascular retinopathy (9.8%) in Buan-Kun, while cataract (56.0%), macular degeneration (6.7%), corneal opacity (6.7%), and phthisis (6.7%) were recorded in that order in Dobong-Ku.

Trachoma and blindness in the Nile Delta: current patterns and projections for the future in the rural Egyptian population.

A population based survey of trachoma and blindness was conducted in a rural Nile Delta hamlet. Trachoma remains hyperendemic in this region. Active trachoma was common among preschool children; over half had moderate to severe disease. Of residents 25 years old 90% had substantial conjunctival scarring. Severe conjunctival scarring was commoner among women (84%) than men (58%), and three-quarters of older women had trichiasis/entropion compared with 57% of older men. Males and females had equivalent age specific rates of inflammatory disease. Blindness was associated with old age; 17% of residents aged 50 and over were blind. Estimates of blindness based on this survey and other surveys in Egypt indicate that blindness is still a serious public health problem in rural Egypt. The number of blind persons in Egypt will increase from an estimated 420,000 in 1980 to 868,000 by the year 2020. The current crude blindness rate of 1.8% is expected to increase to 2.3% in the year 2000 and to 3.2% in 2020.

Childhood Blindness: Dateline Africa

ABSTRACT Prevalence rates of childhood blindness and infant and childhood mortality in Africa are the highest in the world. Major factors contributing to these high rates are similar for both blindness and mortality: malnutrition, measles and other acute febrile infections, malnutrition with xerophthalmia, and limited or poor access to preventive and curative health services. Because of high national growth rates, stagnant economies, and the failure of national health care systems to expand with rapidly growing populations, childhood blindness in Africa likely will remain a significant international public health problem for the foreseeable future.

The Incidence of Vision Loss in a Diabetic Population

The 4-year incidence of blindness and vision loss was examined in a population-based study of diabetes mellitus. In subjects participating in baseline and 4-year follow-up examinations, the rate of blindness was 1.5, 3.2, and 2.7% in younger onset persons, older onset persons taking insulin, and older onset persons not taking insulin, respectively. The rate of blindness increased with increasing age, increasing diabetic retinopathy severity, and lower baseline visual acuity in all three groups. Blindness increased with increasing duration of diabetes in younger onset persons and older onset persons taking insulin. The incidence of vision loss, as measured by a doubling of the visual angle, was associated with older age, more severe retinopathy, and presence of macular edema in the three groups. It was also associated with duration of diabetes, presence of proteinuria, and higher glycosylated hemoglobin in younger onset and older onset persons taking insulin.

CONGENITAL OCULAR BLINDNESS IN CHILDREN 1945 TO 1984

A total of 676 children born in British Columbia with congenital ocular blindness during the years 1945 through 1984 were studied. The birth prevalence rate of congenital blindness has decreased from eight per 10,000 live births in the late 1940s to three per 10,000 live births. Retinopathy of prematurity was replaced by genetic ocular disorders as the leading cause of congenital blindness, although the former is reemerging. The rate of congenital rubella infection also declined. There has been a significant increase in the rate of births with optic nerve lesions during the past 15 years, while the rate of births with lesions of the lens fell, reflecting the decline in the rate of maternal rubella infection. There are fewer children with congenital ocular legal blindness who have no light perception today, and they also have fewer associated handicaps.

Congenital ocular blindness in children, 1945 to 1984.

A total of 676 children born in British Columbia with congenital ocular blindness during the years 1945 through 1984 were studied. The birth prevalence rate of congenital blindness has decreased from eight per 10,000 live births in the late 1940s to three per 10,000 live births. Retinopathy of prematurity was replaced by genetic ocular disorders as the leading cause of congenital blindness, although the former is reemerging. The rate of congenital rubella infection also declined. There has been a significant increase in the rate of births with optic nerve lesions during the past 15 years, while the rate of births with lesions of the lens fell, reflecting the decline in the rate of maternal rubella infection. There are fewer children with congenital ocular legal blindness who have no light perception today, and they also have fewer associated handicaps.

Visual acuity in a diabetic population.

In a population study of all insulin-treated diabetics and a random sample of those treated with oral antihyperglycaemic agents (OHA) in Gotland, Sweden, the visual acuity (VA) was determined. The prevalence rates of visual impairment (VA 0.1-0.2) and blindness (VA less than 0.1) in the insulin-treated group were 4.9 and 4.4%, respectively, and in OHA-treated diabetics 7.2 and 1.4%. The impairment and blindness were due to diabetic retinopathy (Rp) in 72% of the insulin-treated group, but only in 14% of the OHA-treated diabetics in whom cataract and age-related maculopathy were the predominant causes. Blindness was four times more frequent among insulin-treated females than males. On simple logistic regression test VA correlated with Rp, age at examination, age at onset of diabetes, duration of diabetes and sex. However, on multiple logistic regression analysis the only significant relationships with VA were in the insulin-treated group, a correlation with Rp and age; and in the OHA-treated group, a correlation with age only. Thus the higher frequency of blindness in insulin-treated women was explained by Rp and age. When standardizing for age, the fraction of blind patients was found to be significantly higher among the insulin-treated than in the OHA-treated diabetics (6.7 vs 1.4%).

Blindness in Saudi Arabia

Depending on definitions and how you count, an estimated 42 million people are blind. Over 80% reside in developing countries, where blindness rates are often five to 20 times those of wealthier industrialized nations.^1,2The majority of Third World blindness is caused by cataract^3,4; the rest, depending upon local conditions, by trachoma,⁵onchocerciasis (river blindness),⁶malnutrition (xerophthalmia),^7,8trauma, and glaucoma.^2,3It is concentrated in the elderly, particularly women. Most importantly, it can be prevented or reversed with existing technology. In a carefully conducted nationwide prevalence survey reported in this issue, Tabbara and Ross-Degnan⁹document the magnitude and causes of blindness in Saudi Arabia, confirming findings of similar surveys in Nepal¹⁰and Malawi¹¹and more modest investigations elsewhere. These have revealed the unacceptable burden of this avoidable disability, with its economic and human costs, and enabled governments with severely limited resources to

Medical manpower and the labeling of blindness

This study offers an example of how a specific quantifiable proposition can be derived from the labeling perspective. The paper examines the usefulness of labeling theory in explaining the relationship between the distribution of medical manpower and rates of “blindness.” If, as labeling theory suggests, deviance is in the “eye of the beholder,” it is reasonable to expect that rates of deviance will depend, in part, on the number of official “beholders” in the community. In New York State, all physicians and optometrists are required, by law, to report the names of blind patients to the state Department of Social Services. The results of a multivariate analysis indicate that rates of medical manpower have a small, but statistically significant effect on county rates of blindness. Rates of medical manpower, however, do not have a similar effect on most other measures of county mortality and morbidity. This suggests that the relationship between blindness and manpower rates is better explained by a labeling...

Secondary prevention in diabetes mellitus

THE PAPER by Bennett and Knowler is concerned in the main with primary prevention of diabetes. The comments in this discussion will reflect another traditional public health concern, that is, the role of secondary prevention in this disease. Is there a need for screening or examining in a systematic fashion those persons known to have diabetes to determine whether more preventive or therapeutic efforts would benefit this high risk population? I will limit my discussion of this question to the eye and visual function in diabetic persons. Diabetes is a major cause of blindness in the United States and has been estimated to account for 5000 new cases each year [l]. The adverse effects of diabetes on the visual system may occur through several different pathways. Retinopathy is the pathologic process which is most commonly thought to occur in eyes of diabetic persons. In 1979-1980 the Wisconsin Epidemiologic Study of Diabetic Retinopathy was undertaken. That study was designed to determine the prevalence and severity of retinopathy in diabetic persons who received primary medical care in an eleven county area (Health Service Area 1) in southern Wisconsin [2]. All persons whose age at onset of diabetes was less than 30 years and who were taking insulin were examined; these persons have been referred to as the “younger onset” group. A stratified sample of persons who were diagnosed after 30 years of age was also examined; these persons have been referred as the “older onset” group. The population has been described in detail in other reports [3-51. Rates of legal blindness, that is, visual acuity of 20/200 or worse in the better eye may be compared with rates reported from the Framingham Eye Study, and from the Health and Nutrition Examination survey. Rates of legal blindness increased with increasing age in all groups. The rates in the diabetic persons were much higher at each age. In the younger onset persons, the overall rate of legal blindness was 3.6%; about 86% of the cases were attributable to diabetic retinopathy. In the older onset persons, the rate of blindness was 1.6x, and 33% of the cases were caused by diabetic retinopathy [6]. Davidson has cited rates of complications in diabetic patients. Rates of retinopathy, proteinuria, neovascularization, azotemia, blindness, and atherosclerosis all increased in frequency as the number of years of diabetes increased. Retinopathy occurred relatively early in the disease, and was the most frequent of these complications. More than 70% of patients had evidence of retinopathy after 25 years of the disease [7]. There are other recent sources of data that have been used to estimate the rates and severity of retinopathy in diabetic persons. Frank er al. [S] and Palmberg et al. [9] described the experience from their clinic practices in which they examined insulin dependent diabetic patients. Frank et al. reported no cases of retinopathy in 60 patients who had had diabetes for &4 years; Palmberg et al. found no cases in 80 patients who had &3 years of disease, but found 21% when he saw the same group again at 4-5 years. In the Wisconsin population, Klein et al. reported that in younger onset persons with from 0 to 4 years of diabetes, 13.6% had retinopathy [4].