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  1. Rapid assessment of prevalence of cataract blindness at district level.

    Article - En anglais


    To find an optimal cluster size and number of clusters for a reasonable estimate of the prevalence of cataract blindness in people aged =50 years in 19 rural districts of a state in India.


    Cluster sampling methodology was used in 19 rural districts of Karnataka State, India.

    In each district, 15 clusters were randomly selected and 90 people aged =50 years were examined in each cluster.

    As a result the visual acuity and lens status of a total of 22 218 people were assessed.


    For each district, the design effect for cluster size ranging from 20 to 90 was calculated and the optimal cluster size and the required number of clusters to achieve an accuracy of 1% errors and 80% confidence was assessed.


    The age and gender adjusted prevalence of cataract blindness varied from 1.58% to 7.24%, which justifies district level surveys.

    The design effect is nearly 1.5 for clusters of sizes 30 and 40.

    With an average prevalence of 4.93% with 1% error and 80% confidence level, the optimal number of clusters is 37 and 28 for a cluster size of 30 and 40 respectively and the average sample size for a district around 1100.


    Rapid assessments for cataract blindness in those aged =50 years can be conducted at district level in India with existing resources and at affordable costs.

    These provide reliable data, essential for effective monitoring and planning.

    Other parameters, for instance, surgical coverage can also be assessed. (...)

    Mots-clés Pascal : Cataracte, Cécité, Complication, Echantillonnage en grappe, Taille, Epidémiologie, Prévalence, Méthodologie, Homme, Inde, Asie, Etude comparative, Oeil pathologie, Cristallin pathologie, Segment antérieur pathologie, Trouble vision

    Mots-clés Pascal anglais : Cataract, Blindness, Complication, Cluster sampling, Size, Epidemiology, Prevalence, Methodology, Human, India, Asia, Comparative study, Eye disease, Lens disease, Anterior segment disease, Vision disorder

    Logo du centre Notice produite par :
    Inist-CNRS - Institut de l'Information Scientifique et Technique

    Cote : 97-0533640

    Code Inist : 002B09G. Création : 13/02/1998.