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PubMed1997

Double-blindness procedures, rater blindness, and ratings of outcome. Observations from a controlled trial.

BACKGROUND: We determined whether blindness in a double-blind randomized controlled trial of alprazolam and exposure therapies in patients with panic disorder and agoraphobia was maintained in assessors and patients, what were the factors related to "unblinding," and whether unblinding was associated with clinical outcome. METHOD: In 129 patients with panic disorder and agoraphobia who were randomized to alprazolam-exposure, placebo-exposure, alprazolam-relaxation, or placebo-relaxation conditions, blindness was tested at the end of treatment by the independent assessors' and patients' classification of the treatment condition. RESULTS: Assessors' classifications were correct in 82% of the alprazolam group and 78% of the placebo group; corresponding figures for patients' classifications were 73% and 70%, respectively. Factors associated with unblinding included drug side effects but not assessors' ratings of treatment outcome. CONCLUSION: Judgment of the validity of the outcome of a randomized controlled trial is easier if the report notes not only the use of a double-blindness procedure but also details how blind the raters remained and how any unblinding affected their ratings of clinical outcome.

Agoraphobia↗
PubMedDate not supplied

Efficacy of acebutolol in chronic stable angina using single-blind and randomized double-blind protocol.

The clinical effects of a cardioselective beta-adrenergic blocking drug, acebutolol, were studied in 25 patients with chronic stable angina, using a seven-week single-blind placebo leads to acebutolol (mean dose 913 mg/day) phase followed by 12-week randomized double-blind placebo leads to acebutolol (mean dose 968 mg/day) crossover protocol. Objective parameters from exercise treadmill tests showed consistent reduction in resting and maximal exercise heart rate and rate-pressure product during both single- and double-blind phases. Duration of exercise and maximal ST segment depression were not significantly altered. Subjective improvement following acebutolol was observed with reduced frequency of anginal attacks and nitroglycerin consumption during the single-blind phase. However, no differences were seen during the double-blind phase due to significant subjective improvement during the latter placebo period. Adverse effects observed were mild in nature and were similar to those seen with other beta blockers. These data establish acebutolol as a potent beta-blocking agent and emphasize the importance of utilizing objective parameters over subjective variables in demonstrating the clinical antianginal efficacy of a beta blocker.

Acebutolol↗
PubMed1977

[Equilibriometric findings in partially blind and blind children (author's transl)].

26 of both blind or partially blind children were subjected to equilibriometric tests. By way of a vestibular-ocular test they were given the Rotatory-Intensity-Damping test. During the tests the per and postrotatory nystagmus reactions were electronystagmographicly registrated. For the vestibular-spinal tests the Unterberger's stepping test with photographic registration of the body-sway in the Cranio-Corpo-Gram was used. In most of the children you could identify a definite per and postrotatory reaction in spite of considerable spontaneous reactions. The strong eyelid movements of these patients, the intensive spontaneous deviations and diminished corneo-retinal potential made precise judgement of the electronystagmogram difficult. Comparison between the blind and partially blind children enabled the differences to be objectified. Blind-born children have a higher spontaneous activity, slightly diminished per and postrotatory nystagmus reactions and a diminished bodyequilibrium. These results can be explained on one side by habituation and on the other side by efferent structures, which have an inhibitory effect on the vestibular input.

Adolescent↗
PubMed1994

Blind man's bluff: effectiveness and significance of psychotherapy and pharmacotherapy blinding procedures in a clinical trial.

No study has reported on the comparative effectiveness of blinding procedures for psychotherapy and pharmacotherapy conditions in treatment efficacy studies or the potential impact of failure to maintain a psychotherapy blind. In a randomized clinical trial, we found, from the perspective of clinical evaluators who were unaware of the patient's treatment assignment, procedures intended to protect the psychotherapy blind were only modestly effective but comparable to standard procedures used to maintain pharmacotherapy blinds. Second, accuracy of guessing each form of treatment (psychotherapy or pharmacotherapy) was not independent of the other. Third, findings suggested the importance of maintaining both psychotherapy and pharmacotherapy blinds, as subjective ratings of treatment outcome were significantly different depending on whether the clinical evaluator had correctly guessed the patients' true treatment condition.

Cocaine↗
PubMed2005

Double-blind placebo-controlled challenges for peanut allergy the efficiency of blinding procedures and the allergenic activity of peanut availability in the recipes.

BACKGROUND: A firm diagnosis of double-blind placebo-controlled food challenge (DBPCFC) would facilitate the diagnosis in patients with uncertain history of reaction. Guidelines are lacking for an upper provoking dose and how to hide high concentrations of peanuts. AIM: To develop and evaluate a double-blind recipe with minimum 10% of peanut. To compare the recipe with published recipes regarding blindness, taste, texture and immunoglobulin (Ig)E antibody binding to peanut. METHODS: A recipe (I) with 10% of peanut was developed evaluated and used in DBPCFC. The challenges were followed by development of a concentrated recipe (II) (15% peanut, 25% fat). Recipe II was compared with the only published recipe (III) (11% peanut, 7% fat) regarding taste, texture and availability of peanut. Recipe IV (12% peanut, 10% fat) was developed using the same methods. The binding of IgE in the recipes was measured using an inhibition method. RESULTS: During challenges, one patient reacted after 4 g, emphasizing the need for blinding recipes containing high doses of peanut. Evaluation between recipes II and III, only recipe II was regarded as blind by the taste panels. A tenfold lower availability of peanut protein in the recipe II was found at 50% of inhibition. Recipe IV had a better IgE binding that did not differ from the original peanut extract. CONCLUSION: The peanut taste and texture can be hidden in a challenge medium. The fat content was important for the availability of the allergenic protein in challenges. The availability of allergens must be taken into consideration when used for DBPCFC.

Allergens↗
PubMed1990

Blindness and eye disease in Kenya: ocular status survey results from the Kenya Rural Blindness Prevention Project.

A series of eight regional eye surveys were conducted in Kenya as part of the Kenya Rural Blindness Prevention Project. Each survey consisted of clinical examinations of about 1800 individuals selected by a random cluster sampling technique in geographically distinct and culturally homogeneous rural areas; 13,803 examinations were completed in all. Together these surveys provide the basis for national estimates of the prevalence and aetiology of visual loss and ocular pathology. The results showed that 0.7% of rural Kenyans are blind in the better eye by WHO standards, and another 2.5% suffer significant visual impairment. Rates of visual loss tend to increase five-fold in each 20-year age cohort. Females have higher prevalence of visual loss than males over age 20, and certain geographical areas have markedly higher rates. The commonest cause of both blindness and visual impairment is cataract, accounting for 38% of all visual loss. Trachoma (a localised problem), glaucoma, macular degeneration, and severe refractive errors follow cataract as leading causes of blindness in the better eye. Trauma, corneal scars of various causes, phthisis, and staphyloma are important causes of monocular blindness. Nutritional eye disease does not appear to be a problem of any magnitude in rural Kenya.

Adolescent↗
PubMed1995

Causes of childhood blindness in Sri Lanka: results from children attending six schools for the blind.

AIM: The survey aimed to identify the major treatable or preventable causes of visual loss in children attending blind schools in Sri Lanka so that appropriate control measures can be implemented. METHOD: A total of 226 children with blindness (BL) or severe visual impairment (SVI) attending six schools for the blind were examined and details recorded using the WHO standard reporting form. RESULTS: Cataract was responsible for 17% of BL/SVI and was the commonest 'avoidable' cause of childhood blindness. Bilateral microphthalmos accounted for one quarter of BL/SVI. Vitamin A deficiency was not a significant cause of visual morbidity. CONCLUSION: The pattern of childhood blindness seen in this study is typical of a growing number of south east Asian countries which are developing rapidly. Childhood cataract is a major avoidable cause that can benefit from future intervention strategies.

Adolescent↗
PubMed2003

Causes and temporal trends of blindness and severe visual impairment in children in schools for the blind in North India.

AIMS: To describe the causes of severe visual impairment and blindness (SVI/BL) in children in schools for the blind in north India, and explore temporal trends in the major causes. METHODS: A total of 703 children were examined in 13 blind schools in Delhi. A modified WHO/PBL eye examination record for children with blindness and low vision which included sections on visual acuity, additional non-ocular disabilities, onset of visual loss, the most affected anatomical part of the eye concerning visual impairment, and the aetiological category of the child's disorder based on the timing of insult leading to visual loss was administered in all children. RESULTS: With best correction, 22 (3.1%) were severely visually impaired (visual acuity in the better eye of <6/60) and 628 (89.3%) children were blind (visual acuity in the better eye of <3/60). Anatomical sites of SVI/BL were whole globe in 27.4% children, cornea 21.7%, retina 15.1%, and lens 10.9%. The underlying cause of visual loss was undetermined in 56.5% children (mainly abnormality since birth 42.3% and cataract 8.3%), childhood disorders were responsible in 28.0% (mainly vitamin A deficiency/measles 20.5%), and hereditary factors were identified in 13.4%. Study of temporal trends of SVI/BL by comparing causes in children in three different age groups-5-8 years, 9-12 years, and 13-16 years-suggests that retinal disorders have become more important while childhood onset disorders (particularly vitamin A deficiency) have declined. CONCLUSIONS: Almost half of the children suffered from potentially preventable and/or treatable conditions, with vitamin A deficiency/measles and cataract the leading causes. Retinal disorders seem to be increasing in importance while childhood disorders have declined over a period of 10 years.

Adolescent↗
PubMedDate not supplied

Coping with blindness: a survey of 50 blind dogs.

A telephone survey of 50 owners of blind dogs was made in order to assess how well visually deprived dogs can cope within their environment. Ten of the 50 dogs surveyed died or were euthanased as a direct result of their blindness or ocular disease. Three owners were unable to come to terms with their pet's visual loss. Two dogs died as a result of accidents directly associated with blindness and five dogs were euthanased due to pain caused by glaucoma. Twenty-seven owners reported permanent behaviour or temperament changes in their pets. Behavioural changes included a more cautious approach to the environment and closer contact with the owner. Owners were aware of an obvious compensatory reliance on the senses of hearing and smell. Permanent temperament changes were reported in only two dogs both of whom became more aggressive. Only six of the surveyed dogs were unable or unwilling to find their way around in familiar surroundings. The most consistent measures undertaken by owners to ensure the dogs' safety was to prevent access to roads and to ensure that there was minimal movement of furniture within the home. Six dogs lost interest in exercise after the onset of blindness but a further six were still allowed to roam at large. Of the 32 owners who accompanied their dogs eight reported that restraint on a lead was unnecessary. Twenty-eight owners had encountered people who had suggested it was unkind to keep a blind dog.

Aggression↗
PubMed1993

[Integrated model for the prevention of blindness based on the Peruvian Organization for the Campaign against Blindness (OPELUCE)].

Numerous strategies and policies have been designed for the prevention of blindness. Their implementation, however, may find considerable operational difficulties in the developing countries. Following WHO (World Health Organization) recommendations, the Peruvian organization against blindness (OPELUCE) has designed an Integral Model for the Prevention of Blindness in Perú. This model includes the training of health personnel and educators, informing the community on ocular preventive aspects, medical and surgical treatment of patients and training programs for the blind. The model has been modified for its application in urban, and urban-marginal areas as specific programs for the prevention of blindness due to glaucoma, diabetes, and accidents, and for the detection of visual problems at the school level.

Blindness↗
PubMedDate not supplied

Attitudes toward blindness and blind people: what do we believe?

The attitudes of sighted persons are recognized as a major influence on the successful adjustment of blind people to their disability. Although actual measurement is a quite recent development, attitudes toward blindness and blind people have a long history. The purpose of this article is to review the descriptive and research literature that addresses attitudes of sighted and non sighted persons toward blindness and blind people.

Attitude of Health Personnel↗
PubMed2006

To blind or not to blind? What authors and reviewers prefer.

In order to inform discussions about possible changes to Medical Education's blinding policy, members of the journal's editorial board were interested in discovering reviewers' and authors' preferences with regard to the current double-blind policy and various alternatives. In September 2005, an 8-question, web-based survey was sent to all authors and reviewers who had submitted or reviewed a manuscript for Medical Education in 2003 and 2004 (n = 2632). The questions asked about authorship and reviewing experiences and preferences regarding 5 types of blinding procedure, from double-blinding to fully unblinded, open reviews. Following 2 electronic mailings, 838 surveys were completed. There was a range of experience among respondents, with a high proportion of experienced authors (49% with over 20 publications) and reviewers (41% with over 20 reviews). Overall, 68% of respondents preferred a review process that concealed author names and 72% preferred a process that allowed for concealment of reviewer names. Less experienced authors and reviewers were significantly more likely to prefer concealing author names, but even the most experienced respondents had a 54% preference for author concealment. Reasons for concealing identities included facilitating fairness and honesty in reviews and acknowledging the need to avoid personal conflicts or rivalries. Reasons for revealing identities included facilitating greater transparency and accountability, and a better understanding of the author's and reviewer's contexts and credentials. The Medical Education authors and reviewers who chose to respond to the survey voted strongly in favour of continuing the double-blinding procedure of concealing both author and reviewer identities during the review process.

Attitude↗
PubMed2005

Stratification, blinding and placebo effect in a randomized, double blind placebo-controlled clinical trial of gold bead implantation in dogs with hip dysplasia.

UNLABELLED: The purpose of this study was to investigate the need for and choice of stratification factors, and the effects of blinding and placebo in a clinical experiment. Eighty dogs with canine hip dysplasia (CHD) were included in a randomized, placebo-controlled and double blind clinical trial with stratified parallel group design, in which body weight and degree of CHD were used as stratification factors. Thirty-eight dogs were allocated to gold bead implantation and 42 to placebo. After six months, 33 of the 42 placebo-treated dogs received gold bead implantation in an open study lasting a further 18 months. The main outcome variable in the study was change in pain signs of CHD as assessed by the owner. No significant difference in the main outcome variable, regardless of the treatment given, could be detected in the two chosen stratification factors. The only factor to influence the main outcome variable significantly was age. The blinding procedure used in the study, in which 60% of the owners correctly guessed the treatment given, was found sufficient. Of those who guessed the treatment erroneously, 88% believed the treatment given was gold bead implantation. The treatment efficacy after six months in the blinded treatment group was found to be significantly larger compared to the efficacy obtained in the open study. A significant placebo effect was therefore detected. CONCLUSION AND CLINICAL RELEVANCE: The age of the dogs influenced the outcome of the CHD treatment, and is recommended as a stratification factor. A significant placebo effect has to be expected and an optimal blinding procedure is necessary in similar clinical studies.

Age Factors↗
PubMed2005

Non-optical releasers for aggressive behavior in blind and blinded Astyanax (Teleostei, Characidae).

Prior to this study, it was believed that epigean and hypogean Astyanax differ markedly in their display of agonistic behavior. Research suggested that surface-dwelling individuals were extremely aggressive whereas their blind, cave-dwelling counterparts tended to show little or no aggressive behavior. Aggression in Astyanax was thought to be triggered by visual stimuli because surface fish in a dark environment or surface fish blinded late in life did not show aggression. Here, we demonstrate that surface fish blinded early on in their embryonic development are highly aggressive as adults. We also report the first case of a population of blind cave-dwelling Astyanax that is highly aggressive. We conclude that reduced aggression is not the only evolutionary pathway for troglobitic Astyanax and that there is some degree of developmental plasticity in the releaser of aggression and in the selection of its triggering stimuli.

Aggression↗
PubMedDate not supplied

Ocular pathology in The Parable of the Blind Leading the Blind and other paintings by Pieter Bruegel.

Pieter Bruegel the Elder (c.1525-1569) was a well-known 16th century painter who created many realistic canvases related to daily activities of common people of his time. The degree of realism he utilized in his paintings provided a great deal of information about life in the second half the 16th century. He was very talented not only in detailing the human faces in his paintings, but also in reflecting their states of mind. Bruegel's detail has allowed physicians over the years to critically analyze medical conditions in his paintings. This article summarizes certain ophthalmologic diseases depicted by Bruegel. The paper focuses largely on Bruegel's masterpiece, The Parable of the Blind Leading the Blind, because it is perhaps the painter's best known work, and it depicts six blind men, each appearing to suffer from a different cause of blindness. Some other works and their eye pathologies, such as the Adoration of the Magi and The Yawner, are also discussed.

Blindness↗
PubMed1987

Blinding, unblinding, and the placebo effect: an analysis of patients' guesses of treatment assignment in a double-blind clinical trial.

We administered a questionnaire to assess maintenance of patients' blindness at the end of a double-blind clinical trial of Osmotic Release Oral System phenylpropanolamine (PPA) vs. placebo in mild obesity. Seventy-four percent of placebo participants and 43% of PPA participants guessed their treatment correctly. Appetite control was the most frequently reported basis for guessing PPA, even by placebo participants. Lack of adverse drug reactions was the most frequently reported basis for guessing placebo, even by PPA participants. Participants receiving either PPA or placebo and guessing PPA lost more weight, had less diet difficulty, and had more adverse drug reactions than had participants receiving either PPA or placebo and guessing placebo. Although blindness was probably maintained in the PPA group, the placebo group seems to have been, at least at the study's end, unblinded. These results suggest that in double-blind studies, differences in outcome or incidence of adverse drug reactions may act as unblinding factors.

Body Weight↗
PubMed1988

Effect of topical levocabastine on allergic and non-allergic perennial rhinitis. A double-blind study, levocabastine vs. placebo, followed by an open, prospective, single-blind study on beclomethasone.

Forty-four patients, with symptoms of nasal obstruction, sneezing, itching and/or rhinorrhea, were entered into a placebo-controlled, double-blind study to evaluate the clinical efficacy of a topical antihistamine drug, levocabastine, applied 4 times a day for 14 days. At the end of the treatment the placebo patients were treated with levocabastine and the levocabastine patients were treated with beclomethasone dipropionate in a single-blind design for another 14 days. This study showed that levocabastine is significantly more active than placebo with reference to nasal discharge and sneezing. Placebo application improved the symptom score. Levocabastine could not be proved to be more effective against nasal obstruction than placebo in the double-blind trial. In the single-blind set-up, levocabastine resulted in an additional improvement in the score for obstruction, after the placebo period. Although the allergic group tended to respond better, no statistically significant difference could be detected between allergic and non-allergic patients. After treatment with levocabastine, beclomethasone dipropionate administration could not improve the results for nasal discharge and sneezing. For nasal congestion, beclomethasone dipropionate proved to be superior to levocabastine.

Administration, Intranasal↗
PubMed1976

Causes of blindness among students in blind school institutions in a developing country.

Out of 270 students in 17 blind school institutions in Malawi 73 per cent were blind before the age of three. The most common cause for the blindness was ocular infection (75-2 per cent). Meales, as a single cause, was responsible for 43-7 per cent of the cases and smallpox for 5-2 per cent. Bacterial infections were incriminated in 26-3 per cent of the cases. Most of these had received traditional medicine during the acute phase of the disease. Hereditary factors as causes of blindness were found in 7-8 per cent of the cases. These included congenital cataracts (2-6 per cent), optic atorphy of unknown origin (3-0 per cent), microphthalmos (1-5 per cent), and macular degeneration (0-7 per cent). Careful ophthalmological examination showed that in 37 cases an intervention could be attempted in order to improve the vision. In the 11 most favourable cases this was attempted, with the result that nine cases gained a useful vision of 4/60 to 6/18 in the better eye.

Adolescent↗