Myopia and visual acuity impairment: a comparative study of Greek and Bulgarian school children.

Purpose: To compare the proportions of school children with myopia and impaired visual acuity in Greece and Bulgaria.
Methods: A sample of 898 children, aged 10-15 years, was selected from two primary and two secondary schools in a Greek city (Heraklion), and one primary and secondary school in a Bulgarian city (Stara Zagora). Five hundred and eighty eight children were Greek (65.5%, mean age 12.5 +/- 0.08 years) and 310 Bulgarian (34.5%, age 12.4 +/- 0.07 years). VA was assessed with the habitual refractive correction. Refractive error was measured in the absence of cycloplegia using an auto-refractor.
Results: The percentage of children, tested with their habitual refractive correction, with decimal VA <0.5 in at least one eye was 11.7% (95% CI 9.1-14.3%) for Greek and 5.2% (95% CI 2.7-7.6%) for Bulgarian pupils. The percentage of myopic children also differed between the two countries with the proportion with myopic refractive error <or=-0.75 D and decimal VA <0.8 at primary school level being 14.1% and 28.9% in Stara Zagora and Heraklion respectively and 13.0% and 46.9% (95% CI 18.2-29.2%, p < 0.0001) at secondary school level. Among the myopic pupils only 35.8% used corrective spectacles in Stara Zagora, compared to 70.7% of the children in Heraklion. Finally, myopia appeared more prevalent in female adolescents with the effect being statistically significant only for Greek children (55% vs 40% of males, p = 0.015).
Conclusions: The increased proportion of myopic children in Heraklion, compared to Stara Zagora, may arise from a number of environmental and socio-economic factors, which need to be further investigated in order to understand the differences observed among European populations.