title: Prevalence of myopia and hyperopia among urban and rural schoolchildren in Poland.
abstract: BACKGROUND
  Myopia and hyperopia have a significant clinical meaning as they can be the cause of low visual acuity or even blindness. Therefore, there is a high demand for all clinical investigations regarding the development of the eye and the creation of refractive errors. Nevertheless, not many papers have been published around the world which compared the prevalence of myopia as well as hyperopia among metropolitan and provincial schoolchildren. Whereas, in Poland there was not a single paper yet published concerning this topic. That is why the aim of this paper is to describe the prevalence of myopia and hyperopia among urban and rural schoolchildren in Poland.
  
  
  METHODS
  2206 students were examined 1155 boys and 1051 girls, aged 10-14 years, mean age 11.9 (SD = 1.4). 614 boys in the age of 11.8 years (SD = 1.4) lived in the city, as 541 boys in the age of 11.9 years (SD = 1.4) lived in the countryside. 586 girls in the age of 11.8 years (SD = 1.5) lived in the city, as 465 girls in the age of 11.9 years (SD = 1.4) lived in the countryside. The examined students were Caucasian and lived in Szczecin, Poland or in villages located near Szczecin. The examination included retinoscopy under cycloplegia. The refractive error readings were expressed as spherical equivalent (SE). Myopia was defined as SE of at least -0.5 D, hyperopia as SE of at least +1.5 D. Astigmatism among students with myopia and hyperopia was smaller than 1 DC. Data analysis was performed using chi2 test. P values of less than 0.05 were considered statistically significant.
  
  
  RESULTS
  It was observed that myopia occurred more frequently among children living in the city than in the countryside. 13.9% urban and 7.5% rural schoolchildren had myopia (p < 0.001)--table 1. Furthermore, it was found that hyperopia is less frequent among children living in the city than in the countryside. 7.1% urban and 30.8% rural students had hyperopia (p < 0.001)--table 2. It was determined that the average refractive error is lower among children from the city than the countryside--table 3.
  
  
  CONCLUSIONS
  Living in an urban or a rural environment may have an influence on the occurrence of myopia and hyperopia among schoolchildren.
authors.affiliation: Katedra i Klinika Okulistyki Pomorskiej Akademii Medycznej w Szczecinie al. Powstańców Wlkp. 72, 70-111 Szczecin.
authors.forename: Damian
authors.initials: D
authors.lastname: Czepita
authors.forename: Artur
authors.initials: A
authors.lastname: Mojsa
authors.forename: Maria
authors.initials: M
authors.lastname: Zejmo
mesh_terms: D000293:Adolescent; D001251:Astigmatism / Q000453:epidemiology; D002648:Child; D003710:Demography; D005260:Female; D006801:Humans; D006956:Hyperopia / Q000453:epidemiology*; D008297:Male; D009216:Myopia / Q000453:epidemiology*; D011044:Poland / Q000453:epidemiology; D015995:Prevalence; D012423:Rural Health / Q000706:statistics & numerical data; D014504:Urban Health / Q000706:statistics & numerical data