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PubMed1965

CAUSES OF BLINDNESS IN CANADA: AN ANALYSIS OF 24,605 CASES REGISTERED WITH THE CANADIAN NATIONAL INSTITUTE FOR THE BLIND.

A survey of blind persons in Canada, based on registrations with The Canadian National Institute for the Blind (C.N.I.B.), is reported. This is the first study of its type having national scope and based on data registered in a central file. It covered 24,605 living registered blind persons ranging from premature infants to very elderly persons. Causes of blindness are broken down with respect to topography (site and type of lesion) and etiology. In terms of frequency, the principal causes were lesions affecting the globe (e.g. glaucoma, myopia), 36%; the retina, 23%; the lens, 16%; and the optic nerve, 11%. In this study, 32% of the blindness was due to prenatal causes. The prevalence of blindness per 100,000 persons in Canada, based on C.N.I.B. data, was 131, varying among the provinces from 108 to 376. Serious ocular disease was four times more prevalent than blindness; 101,436 such cases (the prevention group) were listed by the C.N.I.B.

Academies and Institutes↗
PubMed1990

Glucose utilization in human visual cortex is abnormally elevated in blindness of early onset but decreased in blindness of late onset.

Glucose utilization has been studied in the visual cortex of blind human subjects, by comparison with normal volunteers, using positron emission tomography. In 6 subjects who became blind early in life ('early blindness'), metabolism in visual cortex was elevated, comparable to that of normal subjects studied with the eyes open. By contrast, glucose utilization in visual areas of 6 human subjects who became blind after completion of visual development ('late blindness') was decreased, slightly lower than in normal volunteers studied with the eyes closed. This unexpected difference between early and late blind subjects might reflect the persistence, in early blindness, of supranumerary synapses which would escape the normal developmental decrease in synaptic density during infancy.

Adult↗
PubMed2004

The blind spot in the nicotine replacement therapy literature: assessment of the double-blind in clinical trials.

While clinical trials of medications often use a double-blind procedure, the integrity of the blind and its relationship to treatment outcome is seldom examined. In this review, 73 double-blind, placebo-controlled clinical trials of the nicotine replacement therapies (NRTs) in smoking cessation were identified. Seventeen articles were found that assessed blindness integrity, demonstrating major variations in the assessment, analysis, and reporting of blindness integrity. Although 12 studies found that subjects accurately judged treatment assignment at a rate significantly above chance, the available literature does not permit definitive conclusions about blindness integrity. Recommendations for the assessment, analysis, and reporting of blindness integrity are made.

Controlled Clinical Trials as Topic↗
PubMed2003

Memory for environmental sounds in sighted, congenitally blind and late blind adults: evidence for cross-modal compensation.

Several recent reports suggest compensatory performance changes in blind individuals. It has, however, been argued that the lack of visual input leads to impoverished semantic networks resulting in the use of data-driven rather than conceptual encoding strategies on memory tasks. To test this hypothesis, congenitally blind and sighted participants encoded environmental sounds either physically or semantically. In the recognition phase, both conceptually as well as physically distinct and physically distinct but conceptually highly related lures were intermixed with the environmental sounds encountered during study. Participants indicated whether or not they had heard a sound in the study phase. Congenitally blind adults showed elevated memory both after physical and semantic encoding. After physical encoding blind participants had lower false memory rates than sighted participants, whereas the false memory rates of sighted and blind participants did not differ after semantic encoding. In order to address the question if compensatory changes in memory skills are restricted to critical periods during early childhood, late blind adults were tested with the same paradigm. When matched for age, they showed similarly high memory scores as the congenitally blind. These results demonstrate compensatory performance changes in long-term memory functions due to the loss of a sensory system and provide evidence for high adaptive capabilities of the human cognitive system.

Acoustic Stimulation↗
PubMed1992

[Social costs of visual handicap and blindness. Rehabilitation resources for blind patients].

UNLABELLED: The number of blind and partially sighted persons in Germany is growing. Increasing social cost and human suffering are related. Measures to counteract this development (e.g. prevention, rehabilitation) are needed. This work gives an overview of the social cost of visual impairment; rehabilitation efforts and needs for eye diseases are considered. MATERIALS AND METHODS: Data from several sources have been analysed in regard to social cost of blindness and rehabilitation efforts for eye diseases: e.g. from the Bavarian and Federal statistical agencies (number of blind and partially sighted), form the German veterans administrations (number of early retired) etc. The results relate to the former Federal Republic of Germany before unification; data from the five new states are not yet available. RESULTS: 1. social cost: The funds needed for blindness compensation payments increased steadily; new figures from Bavaria indicate that in Germany a total of 1,000,000 DM is needed. As a trend the yearly rise over the last 10 years was 6% in Bavaria. Indirect social cost ist caused by early retirement of blind or visually handicapped people; yearly 1% (2000 cases) of all early retirement is due to eye diseases. 2. rehabilitation efforts: For the annual incidence of blind and partially sighted--an estimated 17,000 blind and 50,000 partially sighted--only 12,000 rehabilitation measures are provided in Germany. For the age group over 65 years (which makes up to 60% of all visually impaired) only 800 rehabilitation measures are being completed yearly. In the ophthalmology sector the provision of low vision aids to visually handicapped people is incomplete. A maximum of 60% of all practising ophthalmologists in Bavaria provide this service. On the basis of own data (and from the medical service of medical assistance insurances) it is obvious that 20-50% of the prescribed low vision aids do not fit the requirements of the visually handicapped. In general too high a magnification is prescribed. CONCLUSIONS: More visual rehabilitation services are needed to cope with the growing demand, especially for low vision aids. A prerequisit for a higher coverage with low vision aids is a better reimbursement of the prescribing ophthalmologist by medical assistance insurances.

Blindness↗
PubMed2003

Prevalence and causes of blindness and visual impairment in Bangladeshi adults: results of the National Blindness and Low Vision Survey of Bangladesh.

AIM: To determine the age, sex, and cause specific prevalences of blindness and visual impairment in adults 30 years of age and older in Bangladesh. METHODS: A nationally representative sample of 12 782 adults 30 years of age and older was selected based on multistage, cluster random sampling with probability proportional to size procedures. The breakdown of the cluster sites was proportional to the rural/urban distribution of the national population. The examination protocol consisted of an interview, visual acuity (VA) testing, autorefraction, and optic disc examination on all subjects. Corrected VA retesting, cataract grading, and a dilated fundal examination were performed on all visually impaired subjects. The definitions of blindness (<3/60) and low vision (<6/12 to >or=3/60) were based on the presenting visual acuity in the better eye. The World Health Organization/Prevention of Blindness proforma and its classification system for identifying the main cause of low vision and blindness for each examined subject was used. RESULTS: In total, 11 624 eligible subjects were examined (90.9% response rate) across the 154 cluster sites. A total of 162 people were bilaterally blind (1.53% age standardised prevalence) while a further 1608 subjects (13.8%) had low vision (<6/12 VA) binocularly. Visual acuity was >6/12 in the "better eye" in the remaining 9854 subjects (84.8%); however, 748 of these people had low vision in the fellow eye. The main causes of low vision were cataract (74.2%), refractive error (18.7%), and macular degeneration (1.9%). Cataract was the predominant cause (79.6%) of bilateral blindness followed by uncorrected aphakia (6.2%) and macular degeneration (3.1%). CONCLUSIONS: There are an estimated 650 000 blind adults (95% CI 552 175 to 740 736) aged 30 and over in Bangladesh, the large majority of whom are suffering from operable cataract. This survey indicates the need for the development and implementation of a national plan for the delivery of effective eye care services, aimed principally at resolving the large cataract backlog and the inordinate burden of refractive error.

Adult↗
PubMed1976

Intestinal blind pouch- and blind loop- syndrome in children operated previously for congenital duodenal obstruction.

A follow-up study of 27 children operated for congenital duodenal obstruction (CDO) in the years 1953--71 is presented. Nine children belonged to the intrinsic and 18 children to the extrinsic group of CDO. A total of 7 retrocolic, isoperistaltic, side-to-side duodeno-jejunostomy, 7 Ladd's operation, 8 duodenolysis, 2 reduction of midgut volvulus, 2 duodenostomy a.m. Morton and one gastro-jejunostomy were performed at the age of 1 day--15 years. The clinical and radiological examinations were performed 3--21 years (mean 10 years 2 months) after these operations. In 3 cases there was a moderate duodenal dilatation, but reoperation was not necessary. During the follow-up period, one boy, now aged 8 years, developed a blind pouch-syndrome in the I portion of the duodenum containing a 5 x 5 cm phytobezoar 4 1/2 years after duodeno-jejunostomy. The frequency of blind pouch-syndrome after duodeno-jejunostomy was thus 1:7 or 14%. One girl, now aged 9 years, developed a blind loop-syndrome in the ileocaecal segment 3 months after side-to-side ileotransversostomy, which was performed from adhesion-obstruction after duodenolysis for malrotation I and CDO. Both the blind pouch- and the blind loop-deformation were resected and the children recovered well. To avoid blind-pouch- and blind loop-deformations in the intestines, the anastomosis must be made wide enough, and especially in the surgery of the jejuno-ileo-colic region an end-to-end anastomosis is preferable.

Bezoars↗
PubMed1999

Antigua: blindness prevention, deaf-blind education.

During early November 1998, the Caribbean Council for the Blind, in collaboration with a Boston, Massachusetts (US), organization, Hilton Perkins, held a regional workshop on the education of deaf-blind children. Participants came from Jamaica, Trinidad and Tobago, St. Lucia, Barbados, and Grenada, as well as the host country, Antigua. Following the workshop, there was a further meeting involving a group of international organizations interested in preventing blindness, educating blind children, and rehabilitating blind adults. Participating organizations in the latter meeting included the Caribbean Council for the Blind, Sight Savers International of the UK, the Canadian National Institute for the Blind, Christofell Blindenmission from Germany, and Hilton Perkins International.

Adolescent↗
PubMed1976

Intestinal blind pouch- and blind loop-syndrome in children operated previously for congenital duodenal obstruction.

A follow-up study of 27 children operated for congenital duodenal obstruction (CDO) in years 1953-71 is presented. Nine children belonged to the intrinsic and 18 children to the extrinsic group of CDO. A total of 7 retrocolic, isoperistaltic, side-to-side duodeno-jejunostomy, 7 Ladd's operation, 8 duodenolysis, 2 reduction of midgut volvulus, 2 duodenostomy a.m. Morton and one gastro-jejunostomy were performed at the age of 1 day-15 years. The clinical and radiological examinations were performed 3-21 years (mean 10 years 2 months) after these operations. In 3 cases there was a moderate duodenal dilation, but reoperation was not necessary. During the follow-up period, one boy, now aged 8 years, developed a blind pouch-syndrome in the I portion of the duodenum containing a 5 X 5 cm phytobezoar 4 1/2 years after duodeno-jejunostomy. The frequency of blind pouch-syndrome after duodeno-jejunostomy was thus 1:7 or 14%. One girl, now aged 9 years, developed a blind loop-syndrome in the ileocaecal segment 3 months after side-to-side ileotransversostomy, which was performed from adhesion-obstruction after duodenolysis for malrotation I and CDO. Both the blind pouch- and the blind loop-deformation were resected and the children recovered well. To avoid blind pouch- and blind loop-deformations in the intestines, the anastomosis must be made wide enough, and especially in the surgery of the jejuno-ileo-colic region an end-to-end anastomosis is preferable.

Blind Loop Syndrome↗
PubMed2003

[The application of the integrative management with no blind spot in the cooperative projects for prevention of blindness].

OBJECTIVE: To evaluate the management for donated funds in cooperative projects for prevention of blindness. METHODS: Retrospectively analyze the integrative management with no blind spot in the cooperative projects conducted by the Center of Preventing and Treating Blindness in Anhui Province and the International Organization for Prevention of Blindness from 1992 to 2001. RESULTS: The integrative management such as standardization of fund budget, establishment of inner-controlling system, improvement of inner-management and enhancement of project audit, returning information to donors and obtaining consent were applied in the cooperative projects for prevention of blindness. Therefore, the funds were used reasonably and projects were smoothly accomplished. CONCLUSION: The integrative management with no blind spot is effective for the management of donated funds in the cooperative projects for blindness.

Blindness↗
PubMed1989

Causes of blindness and restoration of sight for the students in the School for the Blind, Khon Kaen.

One hundred and twenty-seven students from the School for the Blind, Khon Kaen, were seen between August 1984 and December 1987. There were 92 males (72.4%) and 35 females (27.6%). The age ranged from 3 to 19 years with the predominant age group being 6-15 years. The majority of the students (95.3%) resided in the Northeast. Only 26 students (20.5%) had positive family histories. Blindness caused by lesions affecting the whole eye was the leading cause of blindness (36.2%). About half of the cases of blindness were preventable and treatable. Most of them (58.3%) were second grade blind. Of all the students seen, 26 students (20.5%) were subjected to treatment for restoration of sight. Only 19 students had complete follow-up post-operative vision. The average visual improvement after treatment was forty-two per cent. The category of blindness was changed to the better side. Blindness was decreased. Visual impairment increased 36.8 per cent after treatment.

Adolescent↗
PubMed1985

Blindness and the validity of the double-blind procedure.

This article describes a method for assessing whether the blindness of a double-blind study is maintained and, if not, whether failure to maintain blindness could have invalidated the results of the study. The benefit of using the method is illustrated in a study of the effect of nicotine gum on the tobacco withdrawal syndrome. In that study, many subjects were able to identify which drug they received; however, a drug effect was present among subjects who correctly identified their drug, among subjects who incorrectly identified their drug, and among subjects who could not tell which drug they received. Thus, failure to maintain blindness could not have invalidated the results of the study. The authors believe double-blind studies should routinely assess blindness, and they recommend their method as a simple and easy way to assess blindness.

Chewing Gum↗
PubMed2001

Causes of childhood blindness in Malaysia: results from a national study of blind school students.

A national study was conducted in children attending six schools for the blind in Malaysia to identify the anatomical site and underlying causes of blindness (BL) and severe visual impairment (SVI), with a view to determine the potentially preventable and treatable causes so that appropriate control measures can be implemented in the future. The standardized clinical examination of eyes was performed and the findings were recorded on the WHO Prevention of Blindness Programme eye examination record form for children with blindness and low vision. A total of 358 children aged between 7 and 17 years were examined, of whom 332 (92.7%) were blind or severely visually impaired. The results relate to these 332 children. Lens was the major anatomical site (22.3%) of visual loss followed by retina (20.8%), whole globe (17.2%), cornea (15.1%), optic nerve (8.7%) and uvea (5.1%). Glaucoma was responsible for BL/SVI in 7.2% and others in 3.6% of cases. Hereditary diseases were responsible for visual loss in 29.5%, intrauterine factors in 4.5%, perinatal factors in 9% and childhood factors in 7.8% of cases. However, the aetiology was unknown in 49.1% of cases which included congenital anomalies of the globe. Childhood cataract and corneal scarring are major treatable causes of BL/SVI that can benefit from future intervention strategies. Perinatal screening for intrauterine factors and hereditary eye diseases, and appropriate interventional therapy will help in reducing the prevalence of childhood blindness.

Adolescent↗
PubMed2007

Causes of blindness and visual impairment in Pakistan. The Pakistan national blindness and visual impairment survey.

OBJECTIVE: To determine the causes of blindness and visual impairment in adults (> or =30 years old) in Pakistan, and to explore socio-demographic variations in cause. METHODS: A multi-stage, stratified, cluster random sampling survey was used to select a nationally representative sample of adults. Each subject was interviewed, had their visual acuity measured and underwent autorefraction and fundus/optic disc examination. Those with a visual acuity of <6/12 in either eye underwent a more detailed ophthalmic examination. Causes of visual impairment were classified according to the accepted World Health Organization (WHO) methodology. An exploration of demographic variables was conducted using regression modeling. RESULTS: A sample of 16 507 adults (95.5% of those enumerated) was examined. Cataract was the most common cause of blindness (51.5%; defined as <3/60 in the better eye on presentation) followed by corneal opacity (11.8%), uncorrected aphakia (8.6%) and glaucoma (7.1%). Posterior capsular opacification accounted for 3.6% of blindness. Among the moderately visually impaired (<6/18 to > or =6/60), refractive error was the most common cause (43%), followed by cataract (42%). Refractive error as a cause of severe visual impairment/blindness was significantly higher in rural dwellers than in urban dwellers (odds ratio (OR) 3.5, 95% CI 1.1 to 11.7). Significant provincial differences were also identified. Overall we estimate that 85.5% of causes were avoidable and that 904 000 adults in Pakistan have cataract (<6/60) requiring surgical intervention. CONCLUSIONS: This comprehensive survey provides reliable estimates of the causes of blindness and visual impairment in Pakistan. Despite expanded surgical services, cataract still accounts for over half of the cases of blindness in Pakistan. One in eight blind adults has visual loss from sequelae of cataract surgery. Services for refractive errors need to be further expanded and integrated into eye care services, particularly those serving rural populations.

Adult↗
PubMed2003

Causes of severe visual impairment and blindness in children in schools for the blind in Ethiopia.

AIMS: To determine the causes of severe visual impairment and blindness in children in schools for the blind in Ethiopia, to aid in planning for the prevention and management of avoidable causes. METHODS: Children attending three schools for the blind in Ethiopia were examined during April and May 2001 using the standard WHO/PBL eye examination record for children with blindness and low vision protocol. Data were analysed for those children aged less than 16 years using the EPI-INFO-6 programme. RESULTS: Among 360 pupils examined, 312 (96.7%) were aged <16 years. Of these children, 295 (94.5%) were blind or severely visually impaired. The major anatomical site of visual loss was cornea/phthisis (62.4%), followed by optic nerve lesions (9.8%), cataract/aphakia (9.2%), and lesions of the uvea (8.8%). The major aetiology was childhood factors (49.8%). The aetiology was unknown in 45.1% of cases. 68% of cases were considered to be potentially avoidable. CONCLUSIONS: Vitamin A deficiency and measles were the major causes of severe visual impairment/blindness in children in schools for the blind in Ethiopia. The majority of causes acquired during childhood could be avoided through provision of basic primary healthcare services.

Adolescent↗
PubMed1995

[Cataract-related blindness in Morocco. The Moroccan Group of Epidemiologic Evaluation of Blindness].

The lack of sound and recent epidemiological data on the prevalence and causes of blindness has hampered the development and evaluation of the Moroccan Programme for the Prevention of Blindness. For this reason a population-based survey using a stratified (urban/rural) sampling design for random selection of clusters was carried out in the Kingdom of Morocco from May 15 until June 30, 1992. The procedures used for this survey were those proposed by the WHO Programme for the Prevention of Blindness. A total of 10,198 people were recruited and 8878 examined for a participation rate of 87%. The size and representativity of the sample satisfactorily guaranteed the order of magnitude and accuracy of eye health indicators used by health planners. The crude point prevalence of blindness was 0.8%, that of bilateral poor vision was 2.3%, and that of unilateral poor vision was estimated to be 2.8%. Based on these findings 195,000 people would be blind and 1,300,000 would be at risk of becoming so, for a total of approximately 1,500,000 people with serious visual impairment. Age-related cataract was the most important cause of blindness (45.5%) and bilateral poor vision (43.1%). The prevalence of cataract-related visual impairment--operable or inoperable--was estimated to be 2.1% of the survey sample. Applying a realistic algorithm to the survey data, it was estimated that the backlog for cataract surgery in Morocco in 1992 was in the order of 502,000 eyes in approximately 287,000 people. The percentage of patients who had undergone cataract surgery in hospital was 0.8%. Posterior lens dislocation according to the traditional "couching" method was noted in 0.1% of people studied. It was estimated that 25% of the demand for cataract surgery was covered by available facilities and that 40% of people with aphakia could not obtain eye care.

Adolescent↗
PubMed2003

The feasibility of external blind DNA proficiency testing. II. Experience with actual blind tests.

The background and goals of a national study to determine the feasibility of blind proficiency testing in U.S. forensic DNA laboratories are discussed. Part of the project involved designing and executing a series of fifteen blind proficiency tests. Execution included biological specimen donor recruitment and case evidence manufacturing. Simulated cases were submitted to DNA laboratories by law enforcement agencies and in some cases by other forensic-science laboratories. Replicate-manufactured evidence was submitted to reference laboratories to simulate the workings of a larger-scale program. Ten tests were straightforward, and essentially tested analytical ability. Five tests involved selecting on the basis of case facts appropriate bloodstains for typing from a bloodstain pattern. We describe in detail our experience in designing and conducting these blind proficiency test trials, and relate those experiences to the overall issue of blind proficiency testing as a quality-assurance tool in forensic DNA laboratories. In this feasibility test series, one blind test was detected by a laboratory, a second one was shown to the lab by law enforcement, and a third was never completed because of lapses in communication. Turnaround times were relatively fast in the independent/commercial labs and relatively slow in the larger public laboratories. Two cross-state case-to-case CODIS "hits" were "planted" among the first series of ten blind tests. One pair was detected. One member of the second pair went to a lab that was not CODIS-ready.

Blood Stains↗