Prevalence of refractive errors in school going children in district Faisalabad, Pakistan

Refractive error is condition in which problem with eye to properly focusing the light rays on retina as a result blurred image formed on retina.1 Normal corneal shape and curvature bent the light and focus on retina properly. But when corneal shape abnormally changed it affect the normal visual process, light not properly focus on retina and image not received clear and it causes blurring of vision.2 Some factors enhanced the refractive errors including Age, diabetes, trauma, many ocular diseases, hereditary, tv use and UV ray’s exposure, use to some drugs (alcohol consumption, antihistamine and anti-depressant) that enhanced refractive errors.3 There are following types of refractive errors including emmetropia, myopia, hypermetropia and astigmatism. Emmetropia is a condition in which no error occurred and rays are clearly focused on retina and clear image formed on retina. Myopia is Also called nearsightedness is a condition in which light rays are focused in front of retina may be due to abnormal corneal structure and elongation of eye ball then average size of eye ball. Due to this patient cannot not see clear distance objects its sees blurred but near objects seen clear. It can be inherited developed in children’s and early adulthood. Hypermetropia is also called farsightedness in which rays focus behind the retina so near objects are blurred but distance objects seen clear. But in case of high hypermetropia both distance and near vision is blurring. It is due shortage of length of eyeball then normal length of eyeball and abnormal shape of cornea. Astigmatism is condition in which cornea has irregular curvature. Curvature and power differ in all meridians of cornea. But has blurred vision at all distances near and far. It causes blurring of vision it is more symptomatic condition then other errors.4 Sign and Symptoms of Refractive Errors: Blur vision, squinting eye, Haloes, Glare, Headache, Eye strain and Rubbing of eyes, dizziness.2 Prevalence of refractive errors in Pakistan, Uncorrected refractive errors: 23.97% among males and 20% among females. Visually disabling refractive errors 6.89% in males and 5.71% in females.5 Total 120 million individuals are affected due to refractive errors in United States.6 Total 153 million peoples are visually impaired due to un-corrected refractive errors and 8 million are blinds in whole world. Prevalence of un-corrected refracted error was highest in low-income poor countries about 90%. Rate of myopia increased due to changes in demography and living life style. Myopia increased rapidly in world from 1.95 in 2010 to 4.76 billion.7 Refractive errors also affect the economy of many countries. Worldwide annual loss of economy due to un-corrected refractive errors is $269 billion. Above 50 years old individuals show index $121.4 billion loss in whole world. Refractive errors are not equally distributed in countries. Myopia is more common and having more prevalence in East Asian countries. Myopia is more common in chines, Japan, Arab and Jew population countries, but less common Negroes and Sudanese population. Prevalence of hypermetropia is greater in Europe and western countries.8 Refractive errors affect children life as uncorrected refractive errors affect child daily life due to poor vision, poor cooperation to daily activities, psychological issues and leading strabismus, anisometropia and amblyopia.9