Visual Impairment among School Going Paediatric Group Children in Rural Areas of Bihar and Jharkhand: A Population Based Study

Objective: The study aims to ascertain the prevalence and cause of low vision/ blindness in children of the rural population of the Indian states of Bihar and Jharkhand and justify the investment done on a population based survey for the particular age group. Material and Methods: The documentation of 1500 children was done with respect to their demographic data and ophthalmological examination. Results: The prevalence of childhood blindness was observed to be 0.2% with a predilection to female sex. The most common cause of visual impairment was uncorrected refractive error with incidences of blindness caused due to correctable condition of congenital cataract. Conclusion: Keeping in view of the life expectancy of 68 years in India, it can be reasonably stated that the number of years of visual impairment that can be shunned by these children oriented population based programs will have a significant impact on the burden being posed.


INTRODUCTION
Epidemiologically, the prevalence of blindness in children varies according to the socio-economic development and under-5 mortality rate of the country in question. The countries in high-income group have a childhood blindness prevalence of 0.3 per 1000 children, while the low-income countries have five times higher prevalence of 1.5 per 1000 children [1]. As per Saxena et al. (2015) [2], the prevalence of blindness in paediatric age group of < 15-year-old in India was 0.8 per 1000 children. The prevalence of childhood blindness is low as compared to that of adults, but the total burden causes considerable loss by affecting the education, probability of getting a job and social welfare of so many children [3].
It is difficult to pin point the cause of blindness and low vision in children. This can be attributed to a variety of reasons, such as low prevalence, rare clinical/ genetic conditions affecting the eye of a child and the high cost to conduct a population based survey for a large sample size. These factors have led to extraction of data by surveying a biased source of blind schools or by reviewing the national registries documenting the childhood blindness. Many countries from Asia, Europe, Africa and USA have documented their findings on childhood blindness by utilising the data from above mentioned banks [4][5][6][7][8][9][10][11]. Though these surveys do provide data on large sample size but for predicting prevalence of blindness in children the data must be verified to have included all the demographic and potential factors to prevent bias [2,3].
The community based eye care programme enabled the collection of data for a population based survey. This led to exclusion of selection bias and was formidable and economic as the primary objective was to provide care to the population. Reports from Australia for children > 6 yrs and > 12 yrs in age, from India for children < 15 yrs in age, from China for children in the age group of 5 -7 yrs and 7 -15 yrs are present in the literature under refractive error study in children (RESC) domain [12][13][14][15][16].
The previous Indian studies mainly covered the southern part of the country [14], therefore, this study was performed as a population based survey of visual impairment in school going children presenting with visual acuity < 6/60 in the better eye, with a prime objective to ascertain the prevalence and cause of low vision/ blindness in children of the rural population of the Indian states of Bihar and Jharkhand.

MATERIALS AND METHODS
Total of six districts from the two states of Bihar and Jharkhand were selected randomly for the survey. A cross sectional study on school going children in rural parts of these six districts was conducted from February 2018 to February 2020. From each district 250 students were examined making a total of 1500 children. Informed consent was taken from parents/ guardian of the children after explaining them the importance, requirement and benefit of the study.
The documentation work was divided into two groups. The first, was responsible to document the name, gender, date of birth and family contact of the children to be examined. The second group comprised of ophthalmologist who measured corrected distance and near visual acuities with logMAR charts, external eye examination included eyelid checking and assessment of pupillary reaction, anterior segment examination using hand held flash light and slit lamp, Goldmann applanation tonometer was applied to measure intraocular pressure and gonioscopy, dilatation of pupil was done to examine lens, vitreous, and posterior segment unless contraindicated because of risk of angle closure.
Statistical analysis was done using statistical software package SPSS for Windows, version 22 (SPSS Inc, Chicago, Illinois, USA). To compare gender based prevalence adjusted odds ratio (OR) was utilised. Ninety-five percent confidence intervals (CI), which accounted for the design effect attributable to clustering, were calculated for all point prevalence estimates and for risk ratios. A statistical significant observation was reported when p-value was less than 0.05.

RESULTS
Out of 1500 examined children, three were blind making the prevalence 0.2% (95% CI 0.05 to 0.39). The age range of these three was 4-9 years, two were female and one male.
Of these three, two (one male and one female) were from rural parts of Bihar and one from rural lands of Jharkhand.
The most common cause of visual impairment among the sample of this study was refractive error, accounting for almost 82.0% of the cause for low vision. Two children (9.1%) from rural parts of Jharkhand presented with corneal opacity, the reason for which was not determined in one of them while in the other it was predicted to be due to vitamin A deficiency which followed a bout of fever due to malaria as per the history provided by the family.
One (4.5%) children each presented with amblyopia which had occurred due to nystagmus and a congenital anomaly of the eye in the form of iridial coloboma ( Table 1).

DISCUSSION
The present study observed 0.2% prevalence of childhood blindness in school going children of rural parts of Indian state of Bihar and Jharkhand. This data is comparable with south Indian data reported by Dandona and Dandona (2003) [17], and both these data are ten times higher than that reported by Lu et al. (2009) [3] in rural population of China. This huge difference can be attributed to the fact that the sample size of the Beijing study of visual impairment in children was 20 times larger than the present study. (2009) [3]. Prevalence of childhood blindness in urban population was reported to be more than the rural population in north Indian study population of Murthy et al.
(2002) [18], study population of Dandona et al. (2002) [17] in south India, southern China population study of He et al. The refractive error can easily be corrected with use of appropriate lens being made accessible to these children and thus reducing the burden of childhood blindness. Apart from refractive error, other condition leading to low vision in childhood as assessed by the present study which could be Commissioner, India, is 68 years, hence, it can be reasonably stated that the number of years of visual impairment that can be shunned by these children oriented population based programs will have a significant impact on the burden being posed [1].
The limitations of the study were the failure to carry out refraction in all the children in order to state whether the subjects had myopia or hyperopia, and as previously mentioned about the lack of data from the urban areas of Bihar and Jharkhand about childhood blindness. Also, due to the low prevalence of childhood blindness, a study with much larger sample size is required to indicate the cause and prevalence of the issue.

CONCLUSION
Despite the limitations, this study presents with the data that can be utilised to plan the strategies enabling the execution of the programs leading to betterment of visual health of the children from the rural setting of the Indian states requiring special attention.

Declaration of interest:
The authors report no conflicts of interest.
Financial Disclosure: No financial support was received.