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Biomedical subjects

B Thylefors

Publications and source records attributed to B Thylefors.

At least 19 recordsLinked to original sources
PubMed1992

The WHO programme for the Prevention of Blindness and cataract in developing countries.

In 1990, the WHO Programme for the Prevention of Blindness estimated that there were 13.5 million unoperated cases of cataract in the world. More than 95% of this backlog is found in developing countries. A conservative estimate of incidence of blindness due to cataract as 1/1000 population/year demonstrates that most developing countries are still unable to provide cataract surgery to the annual load of new cases. The situation is particularly worrying in Africa, south of the Sahara, where only one out of ten cataract ever gets operated on. The WHO Programme has developed a primary health care strategy for the large-scale management of cataract. Identification of cases requiring surgery should be possible at the community level, through training of auxiliary staff. Referral for surgery at the district or province hospital level is possible in most cases, given manpower development. This implies a need for training of cataract surgeons in many developing countries. There should be one cataract surgeon per 250,000 population. Increasing surgical 'productivity' of existing ophthalmologists should be considered as well as improving management of intervention programmes.

Africa↗
PubMed1992

Present challenges in the global prevention of blindness.

Cataract is responsible for 50% of world blindness, with at present an estimated backlog of 13.5 million cases in need of surgery. Low-cost cataract surgery must be made more available in developing countries, making use of alternative approaches for outpatient surgery and optimal management of available resources. Trachoma control needs to be targeted at the worst affected areas in endemic countries, with more emphasis on behavioural, educational and community aspects of the disease. Vitamin A deficiency and xerophthalmia control are becoming matters of maternal and child health care, with early intervention during infancy in view of the mortality issue. There are good prospects for the prevention of blindness from onchocerciasis, through the availability of ivermectin, but large-scale distribution schemes are still needed in most of the African countries concerned. The early detection and management of open-angle glaucoma still poses a major problem in developing countries, and further development of appropriate technology is needed in this field. Another area where more efforts are needed is ocular trauma, which is commonly the cause of unilateral loss of vision. General preventive measures must be enforced and better training provided to health personnel to deal competently with such cases, in order to prevent late complications. Diabetes, finally, is on the increase in many developing countries, giving rise to problems in dealing effectively with the ensuing retinopathy.(ABSTRACT TRUNCATED AT 250 WORDS)

Blindness↗
PubMed1992

Epidemiological patterns of ocular trauma.

Ocular trauma is the cause of blindness in approximately half a million people worldwide, and many more have suffered partial loss of sight. Trauma is often the most important cause of unilateral loss of vision, particularly in developing countries. There is a cumulative risk of ocular trauma and visual loss during life, but the true incidence of accidents involving the eyes is not known. Males tend to have more eye trauma than females, and this is already apparent from childhood; lower socioeconomic classes are also more associated with ocular trauma. The setting for the occurrence of trauma is most commonly the workplace and, increasingly, road accidents. On the other hand, domestic accidents are probably under-reported. Of particular importance in some developing countries is the occurrence of superficial corneal trauma in agricultural work, often leading to rapidly progressing corneal ulceration and visual loss. The impact of ocular trauma, in terms of need for medical care, loss of income and cost of rehabilitation services when indicated, clearly makes the strengthening of preventive measures very worthwhile.

Blindness↗
PubMed1992

[Epidemiological surveillance of trachoma: evaluation and perspective].

World Health Organization (W.H.O.) carried out a survey recently. This survey consisted in a questionnaire to some of its Member States to try to define the importance and world distribution of trachoma. The answers which have been sent by ocular health advisers and/or persons in charge of national ophthalmological institutes showed a systemic lack of significant data to be used for planning or for epidemiological surveillance. Nevertheless, the analysis of this survey seems to lead to the conclusion that trachoma is not still the main cause of blindness in some countries who used to be famous because of an important endemicity. However, trachoma is still a real ocular health and public health problem in numerous other countries, mainly in rural areas and- or areas which are away from socio-sanitary development areas. To have a better quality concerning epidemiological data and to obtain an easier regularity in their collecting, W.H.O. Program for the Blindness Prevention proposed a simplified coding system of trachoma and its complications (S.S.C.T.C.). If this system was accepted by numerous countries it would allow: the use of a simple, reliable and cheap tool to collect epidemiological informations which would constitute an help to take decisions to be able to, give a second start to epidemiological surveillance of trachoma, to have a better idea of the localization of endemic centres of the disease and of this impact on population, to define the needs concerning collective and individual medical and surgical treatments.

Blindness↗
PubMed1992

[Operational applications of the simplified coding system for trachoma and its complications].

In 1987, World Health Organization (W.H.O.) program for the Blindness Prevention proposed a simple system for coding and recording the various stages of Trachoma and its complications. Since this time, this system revealed to be a convenient and useful tool and was used in each epidemiological survey carried out together with Member States, either for blindness prevalence and causes studies as in Benin, Congo, Togo and Turkey, or for specific studies on Trachoma as in Vietnam, Morocco, Mali and in Kiribati. After a short presentation of the most significative results of these studies, the authors discuss on: 1--Details of practical use for this system in the field conditions, underlining particularly: training for future users; setting up of a study concerning reliability: this study has to be both easy an serious to allow an acceptable similarity between the observations of several examiners; some important points to calculate the size of the sample which has to be studied. 2--Main parameters and epidemiological signs which can be took on and invigilated thanks to this system.

Humans↗
PubMed1991

Much blindness is avoidable.

The main strategy of the World Health Organization's Programme for the Prevention of Blindness is to make simple eye care available to all populations. In many countries, national committees are responsible for the optimal utilization of resources and the coordination of work in this field. Several major international nongovernmental organizations provide support. Factors limiting the effectiveness of national programmes are being addressed in WHO collaborating centres.

Blindness↗
PubMed1990

Ocular onchocerciasis and intensity of infection in the community. III. West African rainforest foci of the vector Simulium sanctipauli.

The community pattern of ocular onchocerciasis is described for 11 villages from the forest area in Côte d'Ivoire where S. sanctipauli is the princial vector. An analytical method is applied which relates indices of ocular onchocerciasis with the Community Microfilarial Load (CMFL) and compares the results with the ocular onchocerciasis pattern found in the West African savanna. In spite of high transmission levels as estimated by entomological indices, the CMFLs were relatively low which complicated the characterization of the ocular disease pattern. Nevertheless, it could be shown that ocular onchocerciasis is less severe in the Sanctipauli forest than in the savanna, even after correction for differences in CMFL. The prevalence of onchocercal eye lesions and blindness were low and advanced sclerosing keratitis was completely absent. The differences are explained by presuming strain differences of the parasite Onchocerca volvulus. For given CMFLs the mean microfilarial loads in the eye were significantly lower than in the savanna which suggests that the parasite strain in the Sanctipauli forest is less invasive to the eye. Ocular microfilarial loads were too low to determine if the parasite is also less pathogenic to the eye, as has been concluded previously for foci of S. yahense, but this possibility cannot be excluded.

Animals↗
PubMed1990

Development of training aids for the simplified W.H.O. trachoma grading system. A preliminary note.

A simplified scheme for the grading of trachoma and its complications has been developed by the W.H.O. Programme for the Prevention of Blindness. This scheme has been field-tested in several countries, and the results have demonstrated a good observer agreement. The development of training aids for the use of this scheme by non-specialist health personnel is in progress. This will include a slide series, two manuals for the clinical examination and for the analysis of the reliability of results obtained, plus a simple trachoma grading card for field staff. It is envisaged that these aids will be available as from 1991, and that they will allow a number of countries to set up a system for regular surveillance and evaluation of trachoma.

Humans↗
PubMed1989

Ocular onchocerciasis and intensity of infection in the community. II. West African rainforest foci of the vector Simulium yahense.

A novel method of analysis was used to describe community patterns of ocular onchocerciasis in relation to the intensity of infection in West African forest villages where S. yahense is the sole vector. The pattern is completely different from that found in the savanna, even after correction for the intensity of infection as measured by the Community Microfilarial Load (CMFL). Lesions of the anterior segment of the eye as well as onchocercal blindness either do not occur or occur only sporadically with increasing CMFL in the Yahense forest whilst a steep linear relation exists between the prevalence of these lesions and the CMFL in the savanna. Lesions of the posterior segment of the eye are also less common in the Yahense forest. For a given skin microfilarial load, the ocular microfilarial load is lower in the Yahense forest. For a given ocular microfilarial load, a lower prevalence of eye lesions is found in the Yahense forest compared to the savanna. It is concluded that microfilariae of Onchocerca volvulus in the Yahense forest are less eye invasive than microfilariae from the savanna. Furthermore, they appear to be also less pathogenic to the eye. These findings explain why ocular onchocerciasis is relatively mild in the Yahense forest, in spite of the high intensities of O. volvulus infection in the community.

Animals↗
PubMed1989

Ocular onchocerciasis and intensity of infection in the community. I. West African savanna.

A method is introduced for the analysis of community patterns of ocular onchocerciasis in relation to the intensity of infection as measured by the Community Microfilarial Load (CMFL). Specific features of this method are the clear definition of ocular lesions and their separation into early and advanced stages, and the estimation of the prevalence of onchocercal blindness after exclusion of other causes of blindness. The method is applied to the ophthalmological and parasitological data from 33 villages from the West African savanna in order to obtain a reference pattern for subsequent analyses of ocular onchocerciasis patterns from other bioclimatic zones. In the savanna, there exists a clear linear relationship between most indices of ocular onchocerciasis and the CMFL. Mean ocular microfilarial loads, prevalences of the advanced lesions of the anterior and posterior segment of the eye and prevalences of different classifications of blindness show a high degree of correlation with the CMFL, as does also early sclerosing keratitis. The correlation is poor for the other early ocular lesions. All relationships are similar for the two sexes with the exception of posterior segment lesions which remain more common in males after correction for intensity of infection. The CMFL is superior to the prevalence of microfilariae in the skin as an index of endemicity. It allows a good prediction of the severity of onchocercal ocular disease in savanna communities using parasitological information only.

Adolescent↗
PubMed1987

A simple system for the assessment of trachoma and its complications.

A simple grading system for trachoma, based on the presence or absence of five selected "key" signs, has been developed. The method was tested in the field and showed good observer agreement, the most critical point being the identification of severe cases of the disease. It is expected that the system will facilitate the assessment of trachoma and its complications by non-specialist health personnel working at the community level.

Allied Health Personnel↗
PubMed1986

The effect of 7-8 years of vector control on the evolution of ocular onchocerciasis in West African savanna.

The evolution of ocular onchocerciasis was studied in a cohort of 1170 persons over 5 years of age who were examined before the start of and after 7-8 years of effective vector control in 12 originally hyperendemic villages in the central part of the OCP area. The proportion of the cohort which at the outset of vector control was free from ocular onchocerciasis or had an early or recent infection in the form of punctate keratitis only, remained largely free of or lost their signs of ocular infection respectively and only a very insignificant proportion acquired microfilariae in the eyes or developed a severe onchocercal eye lesion at the initial stage. The proportion of the cohort with a heavy ocular microfilarial load had a reduced risk of developing severe eye lesions and no risk of going blind. The proportion of the cohort with already existing severe eye lesions at the advanced stage remained largely unchanged and some lesions at the initial stage disappeared. Blindness occurred only in those who had severe eye lesions at the outset and was comparatively less than in areas of on-going transmission.

Adolescent↗