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  5. FP1220 : Ocular Morbidity Profile Among Visually Impaired Children in Delhi – A Community Based...

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Dr. Meenakshi Wadhwani, W10817, Dr. Praveen Vashist, Dr. Vivek Gupta, Dr. Suraj Singh Senjam

 ABSTRACT

A population based cross sectional study was planned in 40 clusters of urban Delhi. It aimed for visual acuity screening of 20,000 children aged 0-15 years using age appropriate visual acuity charts. All the children with visual acuity of < 6/12 in any eye in age group between 3-15 years and inability to follow light in age less than 3 years were referred for detailed ophthalmic examination. The interim results for the study in 38 clusters reveal that out of 20,502 children aged between 0-15 years a total of 755children have been referred. Amongst these 755 children a total of 115 children have been found to have presenting visual acuity < 6/19 in better eye. The prevalence of visual impairment (VI) was 0.58%.The main anatomical cause of VI was posterior segment disorders(10.4%) followed by optic nerve abnormalities(5.2%)The main etiological cause of VI in these children was refractive error(86.4%). 

INTRODUCTION

Globally, 1.4 million children suffer from severe visual impairment and blindness, almost two thirds of these live in developing countries.[1]The prevalence of childhood visual impairment amongst 0-15 years of age varies from as low as 0.1/1000 in the wealthiest countries and as high as 1.1/1000 in the poorest countries.[2]

Most of the Indian studies were to determine the causes and prevalence of Childhood Blindness (CHB)and conducted in blind schools or blind registries.[3-5] There are very few community based studies since the low prevalence of CHB means very large sample sizeis required for generating precise and reliable estimates. [6-9] Studies indicate that the major causes of blindness have undergone a paradigm shift from corneal diseases in 1990s to diseases related to whole globe and retina in the 21st century.[10,11]

It is estimated that among ocular morbidities, the cumulative number of blind person years worldwide due to childhood blindness ranks second only after the cumulative number of blind person years due to cataract blindness.[11] Similarly, in terms Disability Adjusted Life Years (DALY) loss also, it is maximum from any other ocular problems. Therefore, prevention of visual impairment and blindness in children is considered a priority under the National Programme for Control of Blindness, and Vision 2020: The Right to Sight India initiative.[12]

To address the lack of recent evidence childhood visual impairment and blindness from North India, we conducted a study with the aim of determining the prevalence of visual impairment and ocular morbidity among children of a north Indian community.

METHODS

This population based cross sectional study was conducted during January 2015 to August 2017 in East Delhi district. The study was initiated after taking due permission from District Blindness Control Programme officer of East Delhidistrict and approval by ethics committee of AIIMS. The reference population for the study were all children who were aged <16 years at the time of visit and staying in the East-Delhi district for 6 months or more.The sample size was calculated to be 20,000 based on an estimated 0.33% prevalence of visual impairment(presenting visual acuity < 6/19 in better eye).[6,7]Probability Proportionate to size with cluster random sampling methods were used to select 40 clusters in the district with a target sample size of 500 children in each cluster.The team included field workers, social workers and optometrists who were trained in study methods before the initiation of the study. To ensure uniformity between refraction inter observer variation assessment was conducted between all the four optometrist with one of the available ophthalmologists as a gold standard. The kappa for this was 0.74 signifying adequate agreement.There weretwo phases in the study, enumeration and detailed ophthalmic examination.

Enumeration and screening

In a cluster, the team performed enumeration through house-to-house visits. Parents of all the children were informed about the nature of the study and informed written consent was requested. Demographic details about the parents and eligible children in visited households were recorded. The children who were not able to communicate and parents of children refusing for giving consent were excluded from the study.History of common ocular symptoms was elicited for each eligible child. Thereafter, unaided visual acuity of enumerated children aged over 2 years was assessed by the study team. Lea symbols chart were used in 3-5 years age group and logMAR tumbling E charts for the 6-15 years age group.For children aged 0-2 years, fixation and following light was assessed using torch light. The screening criteria in field were:unaided visual acuity (VA) < 6/9.5 or unable to fix-follow in any eye, or use of spectacles, or any reported ocular symptoms.Visual acuity was rechecked by optometrist in the field after first screening by vision team and all children with unaided visual acuity < 6/12 in any eye, children wearing glasses, and children who did not fix and follow were referred for detailed ophthalmic examination.Children with ocular symptoms but normal visual acuity and not using glasses were referred to routine primary eye care clinics and were did not undergo detailed assessment. Further evaluation or treatment was provided free of cost to all the study participants. Subjects with refractive error were provided spectacles free of cost. Children identified with low vision were provided with free rehabilitation services and appliances.

Clinical Examination

All the children with unaided visual acuity less than 6/12 in any eye were referred for clinical examination in a centrally based clinic. There an ophthalmologist and optometrists conducted a detailed ophthalmic examination including repeat assessment of visual acuity using retro-illuminated logMAR E charts. Dry and cycloplegic refraction, anterior segment examination and a dilated posterior segment evaluation was also done. Detailed anterior segment examination included Hirschberg test, slit lamp biomicroscopic examination.Pupils were dilated using 2% homatropine or 0.5% tropicamide in case the child was > 10 years with no strabismus.Refraction was performed within 20 minutes of full dilatation of pupils after minimum 45 minutes of instillation of cycloplegic drops and achieving adequate pupillary dilatation. Lensometrywas done to check the power of glasses already worn by the children. The posterior segment was examined using direct and indirect ophthalmoscopes. Treatment for minor eye problems was provided on the spot. Children with major eye problems like pediatric cataract, strabismus, congenital nasolacrimal duct abnormality, retinal degeneration etc.were referred to the base hospital and their treatment was facilitated by the study team. Referred children who did not visit the clinic even after repeated requests were visited at home by the clinical team to minimize attrition.

Statistical Analysis

The analysis was done after entry of the data in a specifically designed database in EpiData. The database was built in validation checks and quality checks. Descriptive analysis of the data was done to identify any outlier and inconsistent values. A 5% of the data was cross-verified to ensure quality of data entry. The entered data was exported and final data analysis were done using Stata13. The standard classification of visual impairment and blindness were followed as per ICD 10 (Table 1).

RESULTS

An interim result of 38 clusters revealed that amongst 8725 households visited, 20502 children were enumerated, of which 19979 (97.4%) underwent screening. We identified755 (3.8%) children with unaided Visual acuity less than 6/12 in any eye. These children were referred by optometrists for detailed ophthalmic examinationat the central clinic. Among these, 687 (91%) children underwent detailed ophthalmic examination.

A total of 115 (0.58%) children were detected with visual impairment (presenting visual acuity < 6/19 in better eye). This included 102 (0.51%) children with moderate visual impairment.5 (0.03%) children with severe visual impairment and 8 (0.04%) children with blindness(Table 2).Causes of visual impairment were assessed amongst the 115visually impaired children. Using the anatomical classification, 12 (10.4%) had retinal diseases as the major anatomical abnormality i.e. 9with chorioretinal degeneration or coloboma, 1 each had ROP, retinoblastoma and dystrophy each, 7(6.1%) children had globe abnormalities i.e.(5)with microphthalmos, 1 had pthisis andanophthalmos each. Amongst 6 (5.2%) children withoptic nerve abnormalities, i.e. 3 withoptic atrophy, 1 had hypoplasia and 2 had other optic nerve diseases.Amongst 6 children with uveal abnormalities i.e.4with coloboma and2 had aniridia. Three children had lenticular abnormalities of which 2 had un-operated cataract and 1had operated cataract. One child had abnormalities related to cornea. The major etiological abnormality was refractive error in 100 (86.4%) of children (Table 3).

CONCLUSIONS

There are a very few population based studies related to the ocular morbidity and prevalenceofchildhood blindness and visual impairment in India. In our study,the prevalence of moderate-severe visual impairment and blindness was 0.58% children in the <15 age group. In a population based study done by Dorairaj etal. in South India, a total prevalence of 0.33% of visual impairment was reported among 13241 children screened. In a population basedstudy done by Kemmanu etal the prevalence of childhood blindness was 0.08% whereas in our study the prevalence was 0.04%. The results will aid development of evidence based policies and programs for addressing the challenge of childhood visual impairment in our country.

REFERENCES

  1. Dandona R, Dandona L. Childhood blindness in India: a population based perspective.Br J Ophthalmol. 2003; 87(3):263-265.
  2. Gilbert CE, AndersonL, DandonaL,Foster A. Prevalence of visual impairment in children:a review of available data. Ophthalmic Epidemiol.1999 Mar; 6(1): 73-82.
  3. Titiyal JS, Pal N, Murthy GV, Gupta SK, Tandon R, Vajpayee RB.Causes and temporal trends of blindness and severe visual impairment in children in schools for the blind in North India. Br J Ophthalmol 2003;87:941‑5.
  4. Bhalerao SA, Tandon M, Singh S, Dwivedi S, Kumar S,Rana J. Visualimpairment and blindness among the students of blind schools in Allahabad and its vicinity: A causal assessment. Indian J Ophthalmol2015;63:254-8.
  5. Kalikivayi V, Naduvilath TJ, Bansal AK, Dandona L. Visual impairment in school children in Southern India. Indian J Ophthalmol. 1997;45:129–34.
  6. Dorairaj SK, Bandrakalli P, Shetty C, Vathsala R, Misquith D, Ritch R. Childhood Blindness in a Rural Population of Southern India: Prevalence and Etiology. Ophthalmic Epidemiology, 2008; 15:176–182.
  7. NirmalanPk, John RK, Gothwal VK, SethuB et al. The Impact of Visual Impairment on Functional Vision of Children in Rural South India: The KariapattiPediatric Eye evaluation Project. IOVS, October 2004, Vol. 45, No. 10.
  8. Kemmanu V, Hegde K, Giliyar SK, Shettey BK etal. Prevalence of childhood blindness and ocular morbidity in a rural pediatric population in Southern India: The PvagadaPediatric Eye disease study-1. Ophthalmic Epidemiology. 2016; 23:3;185-92.
  9. Krishnaiah S, Rao BS, Narasamma KL and Amit G. A survey of severe visual impairment in children attending schools for the blind in a coastal district of Andhra Pradesh in South India. Eye. 2012; 26;1065-70.
  10. National Programme for control of blindness. News letter. The childhood blindness 2011.June –April.
  11. Flanagan N.M, Jackson A.J., Hill A.E: Visual impairment in childhood. Insights from a community based survey Child: Care, Health and development; 2003; 29: 93-99.
  12. Gogate P, Kalua K, Courtright P. Blindness in childhood in developing countries: Time for reassessment?.PLos Med 6(12):e1000117.

Table 1: Definitions of blindness and visual impairment.

Blindness Visual Acuity <3/60 in the better eye with available correction
Severe visual impairment Visual Acuity <6/60 but at least 3/60 in the better eye with available correction

 
Moderate visual impairment Visual Acuity <6/19 but can see 6/60 in the better eye with available correction

 
Early/No visual impairment Visual Acuity <6/12 but can see 6/19 in the better eye with available correction

 

Table 2: Prevalence of visual impairment and blindness in examined population

Examined Early / No VI Moderate VI Severe VI Blindness / FF-ve MSVI & Blindness
Total 19,979 159 (0.8) 102 (0.51) 5 (0.03) 8 (0.04) 115 (0.58)
Age Category
0-2 yrs. 3,245 0 (0) 0 (0) 0 (0) 4 (0.12) 4 (0.12)
3-5 yrs. 3,763 17 (0.45) 6 (0.16) 1 (0.03) 1 (0.03) 8 (0.21)
6-15 yrs. 12,971 142 (1.09) 96 (0.74) 4 (0.03) 3 (0.02) 103 (0.79)
Gender
Male 10,524 77 (0.73) 57 (0.54) 3 (0.03) 5 (0.05) 65 (0.62)
Female 9,455 82 (0.87) 45 (0.48) 2 (0.02) 3 (0.03) 50 (0.53)

* VI- Visual Impairment, FF = Fix and Follow, MSVI=Moderate severe visual impairment 

Table 3: Cause of vision loss amongst children with visual impairment and blindness (n=115)

  Number %
Anatomical Causes    
Whole globe 7 6.1
Cornea 1 0.9
Lens 3 2.6
Uvea 6 5.2
Retina 12 10.4
Optic Nerve 6 5.2
No globe abnormality  80  69.6
EtiologicalCauses
Hereditary Diseases 2 1.6
Intrauterine Factors 1 0.8
Perinatal/Neonatal 3 2.6
Postnatal/infancy/childhood 3 2.6
Refractive error 100 86.4
Undetermined 7 6.0

 

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