Vision Impairment among Children in South India: Results from a Large-Scale School Eye Screening.

PURPOSE: To provide the prevalence of vision impairment and blindness among 250,000 school children aged 6 to 17 years, screened in Tamil Nadu, India. METHODS: The study was conducted between 2016 and 2019 as a part of the school eye screening program in Kanchipuram district, Tamil Nadu. The clinical examination included basic vision testing, objective refraction, subjective acceptance, spectacle dispensing, and a posterior segment evaluation. The prevalence of vision impairment, blindness, low vision, and the association with other demographic variables using logistic regression were calculated. RESULTS: A total of 250,052 children were screened in 1047 schools and the prevalence of vision impairment, blindness, and low vision in Kanchipuram district was 3.83%, 0.01%, 0.19%, respectively. The major causes for vision impairment, blindness, and low vision were refractive errors (3.05%), high myopia (0.002%), and refractive amblyopia (0.04%), respectively. Vision impairment was significantly associated with urban location (OR = 1.42, 95% CI 1.36-1.48, p < .0001), females (OR = 1.11, 95%CI - 1.08-1.15, p < .0001), private schools (OR = 2.43, 95%CI - 2.35-2.42, p < .0001), higher secondary class grade (OR = 1.69, 95%CI - 1.61-1.77, p = .001), high-school class grade (OR = 1.65, 95%CI - 1.58-1.72, p = .001) and middle school class grade (OR = 1.53, 95%CI - 1.47-1.59, p = .001). CONCLUSION: This large-scale school eye screening reports a comparatively lower prevalence of vision impairment, blindness, and low vision when compared to other studies conducted around the world. Although the overall prevalence is relatively low, the causes are mostly refractive. Urban, female, private school-going children aged 11-17 are at higher risk.

Prevalence of color vision deficiency among school-going boys in South India.

Purpose: Impact of color vision deficiency (CVD) on activities at school and productivity at work and consequential psychosocial difficulties has been reported. Although early detection and awareness help in overcoming these difficulties, screening for CVD is not a part of the school eye-screening initiatives in many countries. This study aimed at reporting the prevalence of CVD among school-going boys in Kanchipuram district, South India. Methods: The study was carried out as part of a school eye-screening program (SES) conducted in Kanchipuram district, Tamil Nadu, India for children between 6 and 17 years. The SES followed a three-phased protocol, which also included screening for CVD for all the boys between 11 and 17 years. The boys underwent CVD screening with Dalton's pseudo isochromatic plates (PIPs) followed by confirmation with Ishihara's PIP. The data were analyzed and the proportion of CVD in boys among different class grades, type of schools, location of schools, blocks of the district, and other clinical characteristics are presented. Results: Totally 250,052 children were screened in 1047 schools of which 74986 (60.61%) were boys between 11 and 17 years (mean age: 13.75 ± 1.91). The overall prevalence of CVD was found to be 2.76% (n = 2073; 95% confidence interval [CI]: 2.65-2.88). CVD was associated with urban locations (3.17% odds ratio [OR]: 1.90 95%CI: 1.69-2.13 P < 0.05) and public schooling (2.87%) (OR: 1.29 95%CI: 1.17-1.43 P < 0.05). Boys with CVD were less likely to have vision impairment (P = 0.002) and myopia (P < 0.001) as compared with boys with normal color vision. There was no significant difference in the proportion of other ocular conditions between children with and without CVD (P > 0.05). Conclusion: The study shows a significant proportion of CVD among boys in Kanchipuram district, India and its association with various demographic and clinical characteristics. Identification of CVD and counseling the stakeholders earlier through school children screening is crucial.

Status of Eye Health among School Children in South India - Sankara Nethralaya School Children Eye Examination Study (SN-SEES).

Purpose: To define the prevalence of visual impairment, refractive errors and other ocular problems among school children from the public schools of South India between 2011 and 2015.Methods: This was a cross-sectional study covering 296 schools in the three districts of Tamil Nadu. The school eye screening included visual acuity assessment, external eye examination, objective and subjective refraction, and direct ophthalmoscopy. Vision impairment was defined as logMAR visual acuity of less than 0.2 (Snellen equivalent of 6/9).Results: A total of 91545 children were included with a mean age of 12.9 ± 3.0 years. The prevalence of vision impairment was found to be 5.67% (95%CI 5.53-5.83) and spherical equivalent refractive error was 4.42% (95%CI 4.29-4.56). The prevalence of myopia, hyperopia, and 'other refractive errors' was found to be 3.57% (95%CI 4.01-4.27), 0.03% (95%CI 0.02-0.04), and 0.82% (95%CI 0.76-0.88) respectively. Strabismus, retina and neuro-ophthalmology-related abnormalities, ptosis, and corneal scars were the common ocular problems. In the rural region the prevalence of the refractive errors and the ocular problems were 2.92% and 2.32%, respectively.Conclusion: The study reports a lower prevalence of refractive errors and myopia in this population, much lesser compared to other reported studies from India. Rural regions exhibit an equal need for both refractive services and management of other ocular problems.

Status of eye health among tribal school children in South India.

Purpose: Global trends show a high prevalence of refractive errors among children. The prevalence of vision impairment due to uncorrected refractive errors among school children is increasing and the need for management of other ocular conditions is also reported. This study presents the status of eye health and pattern of daily activities among the school children of a tribal location in Tamil Nadu, South India. Methods: A cross-sectional study was conducted in 13 schools of Karumandurai cluster, Salem district in Tamil Nadu, India. A three-phased comprehensive school screening protocol was conducted to understand the prevalence of vision impairment, refractive error, and other ocular conditions along with a survey about the daily activities of the children at school and home. Results: Among the 3655 children screened, the prevalence of vision impairment was found to be 0.62% (n = 23, 95% confidence interval [CI] 0.42-0.94) and prevalence of refractive error was 0.30% (n = 11, 95%CI 0.17-0.54), among which 0.11% (n = 4) were already wearing spectacles. A total of 44 children (1.20%; 95%CI 0.90-1.61) were found to have other ocular problems and among them, 14 (0.38%) had visual acuity less than 20/30 (6/9). Almost 84% of children required surgical or specialty eye care services. Vision impairment was more in children with other ocular conditions compared to refractive errors (P < 0.001). Conclusion: The prevalence of vision impairment and refractive errors in this tribal area was less. Ocular conditions were more prevalent than refractive errors in this tribal region with the majority of children needing specialty or surgical eye care services. This implies the need for access to secondary or tertiary eye care centers.

Dalton's pseudo-isochromatic plates and congenital colour vision deficiency.

BACKGROUND: Diagnosing colour vision deficiency is vital, owing to its impact on the choice of career and activities of daily living. Conventional screening methods require frequent replacement due to soiling of the materials, and hence are expensive and not feasible for large-scale community screening. This study aims to construct and validate a new screening tool, Dalton's pseudo-isochromatic plates (PIP), addressing the disadvantages of the conventional methods. METHODS: The two phases of the study included the construction and validation of the Dalton's PIP. Construction involved utilising specific wavelengths based on spectral tuning, selection of numerals as targets for the chart and identification of a material with durability and resistance to wear and tear. Validation of the chart was done against the 38-plate edition of Ishihara's PIP by two masked examiners for 1,019 school children aged between 11-17 years (mean ± SD: 14 ± 2 years) as part of a school eye-health program. RESULTS: The sensitivity and the specificity of the Dalton's PIP was found to be 94.12 per cent (95% CI 71.31-99.85) and 99.60 per cent (95% CI 98.98-99.89) respectively and the positive and negative predictive values were 80 per cent and 99.90 per cent respectively. Dalton's PIP when used with a failure criterion of less than three plates correct in two screening sets had the maximum sensitivity and specificity and the area under the curve was 0.96 (95% CI 0.90-0.99, p < 0.05). CONCLUSION: The newly constructed Dalton's PIP is found to be a valid screening tool to detect congenital colour vision deficiency and is comparable to the Ishihara PIP. This screening tool with its shorter screening time, cost and longer durability would effectively serve in large-scale vision screening programs.