The screening of ametropic amblyopia among 17201 pre-school children in Jiangmen City

Objective To investigate the relationship between the incidence of ametropic amblyopia and ametropia among pre-school children.Methods To analyze children's abnormal refractive status by performing vision screening,medical optometry to 17,201 pre-school children from 10 kindergartens in Jiangmen city Guangdong province.Results Among 17,201 pre-school children,the rate of abnormal vision acuity is 15.44%.The incidence of amblyopia is 2.96%.Age group 3～4 years old has the highest abnormal vision acuity rate and the incidence of amblyopia,respectively 19.28% and 4.16%.Age group above 6 years old has the lowest abnormal vision acuity rate,which is 13.35%.The incidence of amblyopia is lowest in age group 5～6 years old,which is 2.45%.The incidence of hyperopia is 79.59%.With the increase of age,it decreases gradually.The incidence of myopia is 2.05%,which increases gradually with the increase of age.While it is 1.83% among 3 year-old children,it grows into 4.35% among 6 year-old children.The incidence of astigmatism is 58.00%,which is quite stable among different age groups.The degree of ametropic amblyopia varies from mild to moderate.The minimum refractive power causing amblyopia is +1.75D of hyperopia,-3.25D of myopia and 1.0D of astigmatism.The minimum refractive power causing anisometropic amblyopia is 1.25D difference of the two eyes in spherical lens,0.75D difference of the two eyes in column lens with exceptional cases in which the difference of myopic anisometropia is 6.75D and hyperopic anisometropia is 3.00D.Conclusion The abnormal vision acuity rate is 15.44%.The incidence of amblyopia is 2.96%.With the increase of age,the incidence of hyperopia decreases and the incidence of myopia increases while the incidence of astigmatism is quite stable.The degree of ametropic amblyopia varies from mild to moderate,mostly caused by hperopia and astigmatism.The minimum refractive power causing amblyopia is +1.75D hyperopia,-3.25D myopia and 1.0D astigmatism.The minimum refractive power causing anisometropic amblyopia is 1.25D in spherical lens and 0.75D in column lens.