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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↗
PubMed1979

Epidemiological aspects of intraocular pressure in an onchocerciasis endemic area.

A field investigation of intraocular pressure in populations in onchocerciasis endemic areas of West Africa revealed a normal pressure distribution in individuals without signs of ocular onchocerciasis or with only microfilariae or reversible lesions in the eye. Females showed a significantly higher mean ocular tension, and in both sexes tension decreased with age. Patients with irreversible onchocercal ocular lesions and signs of anterior uveitis showed a significantly lower and abnormally distributed intraocular pressure. The prevalence of glaucoma was significantly higher in this group, thus indicating that a high intensity of onchocercal infection may be associated with a risk of secondary glaucoma. The presence of microfilariae in the ocular tissues and consequent inflammatory reactions may possibly give rise to an abnormal distribution of ocular tension.

Adolescent↗
PubMed1979

[Aspects of the development of ocular onchocerciasis in West-Africa after three years of simulium control (authors transl)].

In four rural West-African communities with different degrees of ocular affection the development of ocular onchocerciasis has been evaluated after three years of vector control. In the area of a successful disruption of the transmission the population with a slight degree of ocular onchocerciasis before control operations started, did not show an aggravation of the lesions. In those groups severely affected at the beginning of vector control the lesions showed no progression in the majority of the cases. The diminuition of the ocular parasite load, resulting from the reduced transmission, appears to be an important factor in the change of the incidence of blindness and severe ocular lesions attributable to onchocerciasis. Contrary to this the aggravation of ocular lesions was found to be more severe in a community situated in the area reinvaded by the vector than in those that did not experience a reinvasion of the fly.

Adolescent↗
PubMed1978

Aspects of corneal changes in onchocerciasis.

The distribution of living and dead microfilariae in 160 cases of ocular onchocerciasis has been studied. A model for coding the densities in 9 different areas of the cornea has been used. The average numbers of microfilariae and onchocercal punctate opacities per square millimetre were assessed. The highest densities were found in the superficial one-third of the corneal stroma at the periphery of the nasal and temporal parts of the cornea. Sclerosing keratitis was also recorded, and the average age of the patients in this group was significantly higher than in the group with non-sclerosing onchocercal involvement. Corneal thickness measurement showed that the presence of microfilariae or onchocercal punctate opacities or a faint uveitis did not influence the values. In sclerosed areas the corneal thickness varied greatly and was dependent on the degree of the vascularisation. The routes of entry of microfilariae into the eye are discussed on the basis of the distribution patterns of microfilariae and onchocercal opacities.

Cornea↗
PubMed1978

Visual field defects in onchocerciasis.

Lesions in the posterior segment of the eye in onchocerciasis may give visual field defects, but so far no detailed investigation has been done to determine the functional visual loss. Examination of the visual fields in 18 selected cases of onchocerciasis by means of a tangent screen test revealed important visual field defects associated with lesions in the posterior segment of the eye. Involvement of the optic nerve seemed to be important, giving rise to severely constricted visual fields. Cases of postneuritic optic atrophy showed a very uniform pattern of almost completely constricted visual fields, with only 5 to 10 degree central rest spared. Papillitis gave a similar severe constriction of the visual fields. The pattern of visual fields associated with optic neuropathy in onchocerciasis indicates that a progressive lesion of the optic nerve from the periphery may be responsible for the loss of vision. The visual field defects in onchocerciasis constitute a serious handicap, which must be taken into consideration when estimating the socioeconomic importance of the disease.

Adolescent↗
PubMed1978

Ocular onchocerciasis.

Well over 20 million people in the world are infected with Onchocerca volvulus and it is probable that 200 000-500 000 people are blind as a result of this infection, which is the most important cause of blindness in certain areas of Africa and Latin America.Treatment of the disease is difficult and often produces serious adverse reactions in the patient. Combined use of diethylcarbamazine citrate and suramin is still the most suitable form of treatment. Screening for the early detection of cases at high risk of ocular manifestations must be organized, and their treatment undertaken, if blindness is to be avoided.Prevention of ocular onchocerciasis is feasible, using vector control methods to reduce transmission, but the procedures are costly and may have to be maintained for many years.Research is needed to improve treatment and to find a chemoprophylactic agent or a preventive vaccine.

Diethylcarbamazine↗
PubMed1977

Vision screening of illiterate populations.

To assess the amount of reduced vision in a population is an important public health matter, especially in areas where blinding diseases are endemic. Testing visual acuity is, however, a complex problem when a major part of the population is illiterate. The best-known test of vision is the E-test, but this produces the problem of untestability in illiterate populations.The introduction of the Sjögren hand-test as an alternative to the E-test for vision screening of unselected illiterate populations in West Africa resulted in a highly significant reduction of untestability. For certain vision levels it is possible to correlate the results of the hand-test directly with those of the E-test. The hand-test is less well defined than the E-test, but has important advantages for the purpose of vision screening of illiterate populations.

Adolescent↗
PubMed1977

The microfilarial load in the anterior segment of the eye. A parameter of intensity of onchocerciasis.

The presence of microfilariae of Onchocerca volvulus in the eye is associated with an increased risk of deterioration of existing eye lesions. An opthalmological and parasitological examination of 630 persons was carried out in a hyperendemic focus of onchocerciasis in northern Togo. The prevalence of microfilariae increased in the cornea as well as the anterior chamber up to the age of 40-50 years, then decreased. The prevalence of onchocercal punctate keratitis, on the other hand, showed a peak for the age group 10-20 years. In two-thirds of the cases microfilariae were present in the anterior chamber as well as in the cornea. The relative distribution of microfilariae between the anterior chamber and the cornea did not change with the development of severe anterior lesions but in cases with severe posterior lesions relatively more microfilariae were found in the anterior chamber than in the cornea. In all cases of severe ocular lesions the numbers of microfilariae both in the anterior chamber and in the cornea were increased. The average number of microfilariae in the eye can be used as a parameter to enumerate the severity of ocular onchocerciasis.

Adolescent↗