Refraction in Preschool Children in Kazanlak, Bulgaria.

Introduction: The refractive state of the eye changes as the eye's axial length increases and the cornea and lens flatten. In general, eyes are hyperopic at birth, become slightly more hyperopic until the age of 7, which at this point we see a myopic shift toward plano until the eyes reach their adult dimensions, usually by about the age 16.

Aim: To determine the prevalence of refractive error in preschool children aged 3 - 6 in the city of Kazanlak, Bulgaria.

Materials And Methods: A cross-sectional study was conducted in a kindergarten based school within the city of Kazanlak, Bul-garia. Out of 15 kindergarten schools, 10 chose to participate in the study. The children underwent non-mydriatic refraction screening using a Plus-Optix S12с mobile camera. Myopia, hyperopia and astigmatism were defined as being a spherical equivalent (SE) ≤ -0.50 D, SE ≥ +2.00 D and cylindrical diopters ≤ -1.00 D.

Results: A total of 596 children were screened. Out of these 596 children; 526 were with ametropia (470 hypermetropia, 46 myopia) and 50 had astigmatism. Strabismus was found in 12 children, with a further 8 children suffering from amblyopia and finally 8 children were also found to be diagnosed with anisometropia. In 8 cases there were no results due to opacities or due to the small size of the pupil.

Conclusion: The prevalence of refractive error in preschool children is similar to that found in other research in the field. While most cases fall into the category of emmetropia or mild hypermetropia, most of the children had never been to an ophthalmologist. A manda-tory checkup should be issued for all children below the age of seven.