Prevalence of Myopia in School ChildrenReferredtoAin Shams Ophthalmology OutpatientClinic

Abstract

SUMMARY T he cornea and the crystalline lens are responsible for the power of the eye. Optimal vision is contingent upon transparency of the cornea.More than 60% of the total refractive power of the eye is attributed to the cornea. The lens is remarkably specialized epithelial tissue that is responsible for fine-tuning of the image that is projected on the retina. To perform this function it must be transparent. Accommodation is a dynamic optical change in the diopteric power of the eye following the point of focus of the eye to be changed from distant to near objects. Emmetropia is the refractive state in which parallel rays of light from a distant object are brought to focus on the retinain the non accommodating eye. Ammetropiarefers to absence of emmetropia,where the far point of the eye is not at infinity. Ametropia can be classified by presumptive etiology as axial or a refractive. In axial ametropia, the eyeball is either unusually long (myopia) or short (hyperopia). In refractive ametropia, the length of the eye is statistically normal, but the refractive power of the eye is abnormal. In myopic eye (with accommodation relaxed), light rays from an object at infinity converge too soon and thus focus in front of the retina, resulting in a defocused image on the retina. Although myopia is present only in 2% of children when entering school, its prevalence increases markedly during the school years. Myopia is a significant global public health concern with a rapid increase in prevelance in recent decades worldwide. Different studies have adopted different definitions of myopia. The lack of uniform criteria has led to difficulties in comparing prevalence rates in different studies. The "gold standard" for measurement of refractive error in children is cycloplegic refraction. Cycloplegic refraction is especially important in children and infants, as they have strong accommodative responses. There is considerable geographic variation in the reported prevalence of myopia. The prevalence of myopia varies with time and the age of the study population. A possible reason for the increase in myopia rates in many countries is the increase in formal education, with more time being spent on closeup work. Sex and race also affect the distribution of myopia. Numerous studies have tried to elucidate the aetiology of myopia. However, the exact aetiology of myopia is still unclear. The biological theory of myopia views myopia as the result of genetically determined characteristics of eye tissues, whereas the use-abuse theory views myopia as the result of habitual use of the eye at a near focal length, near-work. Myopia is commonly classified into three groups: mild (≤3.0 diopters, D), moderate (>3.0 D), and high (>6.0 D). The most common symptom associated with uncorrected myopia is blurred distance vision. Myopia can be simply classified into simple myopia and pathological myopia. Simple myopia is the condition in which near-sightedness is mild and non-progressive. Pathological myopia is the condition in which shortsightedness is severe and progressive.Besides the direct economic and social burden of myopia, associated ocular complications may lead to substantial visual loss. Management of Myopia include: Spectacle correction, Contact lens and Refractive Surgery. The current study is a cross-sectional descriptive study was conducted on 100 patientsvisited El Demerdash Ophthalmology outpatient clinics in Ain Shams University Hospitals. All patients were subjected to full ophthalmic examination. The current results include: Prevalence of myopia to other errors is 20%. In females, Prevelance of myopia in relation to other errors in the same gendre is 33.3%. In males.Prevelance of myopia in relation to other errors in the same gendre is 14.3%. So, Development of a national survey for detection of visual problems for school-aged children is recommended.