Prevalence of amblyopia in Bulgaria

Introduction: The purpose of this study was to establish the prevalence of amblyopia in children, aged 4 to 10 years, in Bulgaria, who underwent a complete eye examination.Methods: The study was designed as cross-sectional epidemiological study, and the results were calculated in percentages. A complete ophthalmological examination was performed on 1,675 children, aged 4 to 10 years (mean age 7.7 years), during the period 01 Feb 2017-21 April 2017, in five cities, in the western part of Bulgaria. All children were verbal, none of them had a neurologic deficit or mental development delay and a complete examination was successfully performed. The ophthalmological examination consisted of: autorefractometry (using pediatric autorefractor with infrared photoretinoscopy), visual acuity, best-corrected visual acuity (BCVA) and visual acuity with pinhole occluder, cover/uncover and alternate cover test, Worth four-dot test, stereopsis, biomicroscopy and funds examination. Amblyopia was defined as reduction of the BCVA for near and far distances under 40/60 on one or on both eyes in the absence of any pathology of the eye, excluding a pathology leading to stimulus deprivation amblyopia, and in the presence of an amblyogenic factor.Results: Out of 1,675 children, 42 (2.5%) were diagnosed with amblyopia: 7% had strabismic amblyopia (3), 59% had anisometropic amblyopia (25), 31% had isoametropic amblyopia (13), and 3% deprivation amblyopia (1). Unilateral amblyopia was diagnosed in 73% (27) of the cases and bilateral amblyopia in 27% (15). For 45% (754) of the children, it was their first visit to an ophthalmologist.Conclusions: The prevalence of amblyopia among these patients (2.5%) is correlating well with the expected, based on data from other authors, between 1.5% and 3.5%. The fact that nearly half of the children (45%) have not been examined by an ophthalmologist is, however, alarming. The lack of a national screening program in Bulgaria could be the main reason. Other factors include: insufficient number of pediatric ophthalmologists in the country and the lack of awareness among the parents.