Assessment of Influence of Various Eye Parameters in Emmetropia Children on Myopia Development

Abstract

Purpose. To evaluate changes of anatomical and functional parameters of the eye in children with initial emmetropia and to assess their impact on the occurrence of myopia. Patients and methods. 189 children: 85 boys (44.97 %) and 104 girls (55.03 %) aged 7–11 years (mean 8.5 ± 1.01 years) with emmetropia were examined. Ophthalmic examination consisted of refractometry, keratometry with registration of the radius of corneal curvature (CR) on the RC-5000 autorefractometer (Tomey), visual acuity testing with and without correction, positive relative accommodation (PRA), optical biometry with axial length (AL) measurement were performed with a IOL-master biometer (Carl Zeiss). Results. 87 schoolchildren (56 girls (64.4 %) and 31 boys (35.6 %)) of the 189 healthy children had myopia (p = 0.017) by the end of 5-year observation period. Myopia was more prevalent in girls (53.8 %) than boys (36.5 %). There was a statistically significant difference in the values of the ratio of the axial length to the CR in children with stable emmetropia and developing myopia: 2.9 ± 0.06 and 2.95 ± 0.07 (p < 0.001). PRA at the beginning of the study was lower in children with subsequent myopia in comparison with children with stable emmetropia (3.76 ± 0.72 diopters and 4.1 ± 0.7 diopters, p = 0.002). Change of AL was 0.58 ± 0.39 mm in healthy young children (7–8 years old) and 0.44 ± 0.29 mm — the oldest (9–10 years old) (p = 0.021). Increase of AL in case of myopia was 1.55 ± 0.67 mm in children of the younger age group and 1.13 ± 0.32 mm in the older one (p = 0.011). Conclusion. Higher ratio of the axial length to the radius of curvature of the anterior corneal surface was noted in children with developing myopia compared with stable emmetropia. Decline in positive relative accommodation before clinical manifestation of myopia was revealed. A greater increase of axial length was noted in children of 7–8 years of age compared with children of 9–10 years of age in groups with stable emmetropia and with developing myopia.