Changes of eye refraction, corneal power and lens power during growth in emmetropia, myopia and hyperopia

Introduction
The aim of this study was to evaluate changes of eye refraction, corneal power and lens power during growth in emmetropia, myopia and hyperopia.

Material and methods
We examined 183 children (363 eyes) aged 4 to 19 with emmetropia, myopia and hyperopia. All measurements were performed after cycloplegia with 1% tropicamidum. Total refraction and corneal power was examined with autokeratorefractometer. Then we used ultrasound biometer Ocuscan (Alcon, USA), to measure axial length of the eye. Lens power was calculated with use of SRK II formula.

Conclusions
Mean refractive error in whole group in the age of 4 was +2,86D and was gradually decreasing to reach 0D in the age of 14. Between 4th and 14th years old, myopia increases slowly and then acceleration of this process was observed. In hyperopic eyes between 4th and 16th years old, refractive error decreases gradually and then stabilization was noted. Mean corneal power between 4th and 19th years old, decreased in emmetropia and myopia by 1.24D and 2.19D respectively, and increased by 0.38D in children with hyperopia. This changes took place before 10th years old. Mean lens power between 4th and 19th years old, decreased in emmetropia by 2.01D, in myopia by 1.43D and in hyperopia by 1.78D. This changes took place before 12th years old.