January 2004

Can we train "community workers" to screen for paediatric ocular disorders? Praveen K.Nirmalan, S.Rema, S.Sheeladevi and P.Vijayalakshmi

Childhood blindness is a priority for VISION 2020 and there has been much ongoing discussion to develop strategies addressing childhood blindness. Among these is screening for paediatric ocular morbidity, which primarily aims to prevent vision loss that can be permanently disabling. Although several studies from Scandinavia report a reduced prevalence of amblyopia attributable to preschool screening, there have been recent debates on the appropriateness of screening for paediatric visual disorders, especially in the preschool age group. Apart from the relatively low prevalence of childhood blindness and the competition for resources with the more prevalent adult blindness, there are several other issues that need to be considered while developing strategies, especially for economically underprivileged countries. The capacity at different workforce levels to absorb the additional workload involved with this "new" priority is one issue. The ability and capacity to provide treatment for those screened is another. Capacity building - both infrastructure and human - is an ongoing process in eye care. The difficulty in screening children, in determining the appropriate age, frequency and site (home, school) for screening must also be considered. An additional dilemma would be selecting the personnel for the screening - should we use the practically nonexistent cadre of "paediatric" ophthalmologists to screen, taking time away from their clinical duties at base hospitals, or a depleted optometry cadre? Or, should we develop a "community worker" cadre for primary screening? Should this community worker be part of the already "target burdened" existing health worker cadre or a new entity altogether?

An additional consideration is the child Vision screening for children requires sufficient cooperation from the child, and is usually reliably obtained from the age of 3 years upwards. The fourth year of life is considered the best age for vision screening in children. Although vision assessment can be included as part of the general preventive care examinations, reports suggest that results using general practitioners or paediatricians are generally poor because they usually lack the experience required to test vision in these age groups. We designed the Kariapatti Paediatric Eye Evaluation Project (KPEEP) focusing on developing an appropriate model for community-based eye care service delivery to children aged 15 years or younger residing in Kariapatti- a rural block of Virudhanagar district of Tamil Nadu state in India.

We divided the project area of Kariapatti (144 hamlets, estimated 95,000 population) into 6 sectors of approximately 15,000 persons each based on access and distance between villages. We randomly chose 74 hamlets from these 6 sectors with a total estimated 35,000 population including 10,000-12,000 children to test the model using trained community workers to screen for paediatric ocular morbidity. We included all children who were full time residents of these 74 hamlets in this phase. We recruited 10 community workers who had completed at least secondary schooling and were full time residents ofthe project area. Asenior orthoptist (SR) of the paediatric ophthalmology department of Aravind Eye Hospital provided training for the recruited community workers. The training lasted one week and focused on identifying ocular abnormalities and estimating vision. Field visits were arranged such that community workers could have additional "hands on" learning experience. Each worker was provided training to measure visual acuity using Cambridge crowded cards and cake decorations, and to perform a basic ocular examination using a torchlight. Additional theoretical inputs to the community workers included details of the basic anatomy of the eye, and common disorders of the eye.

Each community worker was certified as capable of independently examining children after verification by the orthoptists. After training, each worker enumerated residents within the 74 hamlets by a door-to-door survey and obtained the demographic details of residents of each household. On an average, each community worker contacted 20 households per day and covered the population of approximately 7 hamlets. Visual acuity was measured separately for each eye at 3 meters distance using Cambridge crowded cards in children 4 years and above, and cake decorations for children aged 2 to 4 years. Community workers assessed the ability of the child to fix centrally, maintain fixation steadily and follow the torchlight, if the child was aged less than 2 years. After completion of the vision test, the community worker performed a basic torchlight examination of the eye. This focused on identifying obvious abnormalities involving the lids, conjunctiva, cornea, and lens, and presence of strabismus or abnormalities in ocular movements. The focus at this stage was to merely identify the presence of any abnormality, and not to make a specific diagnosis. The community worker referred children having any ocular abnormality on examination, or history of previous ophthalmic problems, or surgery for ophthalmic conditions or those who had previously been advised spectacles, for further examination by the clinical team. The community workers also referred any child with vision worse than 20/40 in either eye, or a two-line difference in visual acuity between eyes for further clinical examination. Training for community workers was repeated at 3-month intervals, usually for two days with an emphasis on examination techniques. A paediatric ophthalmologist and a refractionist trained in assessing vision and performing refraction in children screened the children referred by the community worker. These clinical examinations were arranged at screening sites within the hamlets; we arranged a minimum of one such site examination for each worker. Additionally, an ophthalmologist performed random rechecks for quality assurance during fieldwork for 371 children from 10 hamlets (one randomly selected hamlet per field worker). Additionally, a random subgroup of children identified as normal by the community worker (after excluding children of the 10 hamlets selected randomly for field checks) went through repeat clinical examination at the screening sites. We defined positive predictive value (PPV) as the probability that a child identified as having a disorder by the community worker actually has a disorder. We defined negative predictive value (NPV) as the probability that a child identified as not having a disorder by the community worker actually does not have a disorder. The Community workers screened 10605 (94.6%) of 11206 enumerated children from the 74 hamlets over a period of six months. 6.2 (95%CI: 1.5, 11.0) per 10,000 children were blind according to WHO criteria; 42.9% of this blindness was potentially avoidable. The population prevalence of ocular morbidity including visual impairment for all ages was 2.6% (95%CI: 2.3, 3.0). The positive and negative predictive values were 24.9% and 93.5% respectively. Field workers screened children of the remaining 70 hamlets within Kariapatti after completion of the first phase of 74 hamlets and determined population prevalence of ocular morbidity to be 2.7% (95% Cl: 2.1, 3.2). The predictive values are dependent on the prevalence of the condition under study and the specificity of the test. We found low positive predictive values for ocular morbidity although the negative predictive values were higher than 90%. Thus, the probability for a child to have no disease if the community worker identified the child as free of disease was over 90% while the probability that a child actually had disease when the community worker identified the child as diseased was about 25%. Targeting screening at groups with higher prevalence of disease can minimise the additional burden on the eye care delivery system because of its impact on the predictive values. Tests with greater specificity result in a greater increase of the predictive values than tests with greater sensitivity.

Issues that need to be considered while developing a screening programme for children in developing countries should include the relatively lower prevalence of paediatric ocular disorders, the paucity of trained paediatric ophthalmologists and support staff including orthoptists and optometrists, and the lack of current service to this target group on a population basis. In the absence of enough numbers of trained ophthalmologists, orthoptists and optometrists, using clinical personnel for screening may often be at the expense of providing tertiary care, and may not be the best use of expertise. However, the same lack of adequate numbers of trained personnel often translates to large segments of the population not receiving eye care services. Our results suggest that community workers can be trained to effectively bridge this gap and to identify children with ocular abnormalities through communitybased screening. It is a moot point if such training should develop a new cadre of workers or can be provided to many persons within the same community such that this knowledge is internalised in the community and would then probably not necessitate a cadre of workers devoted to this activity. Our results suggest that people within rural communities can be trained effectively, which may include self help group members, workers of developmental organisations, volunteers, community groups, etc. We suggest that the focus of such screening should be on not missing children with abnormalities even if the screening process then brings in a large number of false positives. Screening should not be limited to screening for vision impairment alone. As effective interventions for paediatric ocular disorders are available and lead to better outcomes early in the natural history of the disease, reducing the number of false negatives may be more important than reducing false positives. Thus, the screening programme should aim for a negative predictive value around 95% or higher. Based on our results, we recommend that screening programmes that utilise community workers for paediatric ocular morbidity aim to identify children with any abnormality (including vision impairment) irrespective of clinical significance (instead of focusing on vision impairment alone), especially for the preschool children. Although false positives have financial and logistic implications for service delivery programmes in developing economies, our results suggest that the number of false positives is likely "to decrease over time as community workers become more experienced in screening children especially if refresher training is provided. However, it must be kept in mind that screening programmes should not be initiated unless provisions for follow up care are available. (Further details of the baseline results of this project have been published in Nirmalan PK, Vijayalakshmi P, Sheeladevi S, Kothari MB, Sundaresan K, Rahmathuliah L. The Kariapatti Paediatric Eye Evaluation Project (KPEEP): Baseline ophthalmic data of children aged 15 years or younger in south India. American Journal of Ophthalmology 2003; 136:703-709). The authors acknowledge the generous support received from SEVA Foundation and Seva Society, Canada towards this project. Dr. Praveen K.Nirmalan LAICO, Aravind Eye Care System 72, Kuruvikaran Salai, Gandhi Nagar Madurai-625 020, Tamil Nadu, India Tel: +91-452-5356100 Fax: +91-452-2530984 Email: praveen@aravind.org