Induced peripheral defocus and the shape of the posterior eye pole in orthokeratological myopia correction
For the first time a parallel comparative study of peripheral refraction and the retinal contour of intact moderately myopic eyes and those subjected to orthokeratological correction was undertaken. The study involved 32 children aged 9-16 (mean age 12.2±0.29). Peripheral refraction was measured with a binocular open field autorefractometer Grand Seiko WR 5100K (Japan), while peripheral eye length was measured with the help of IOLMaster (Carl Zeiss, Germany) at 4 identical spots of 15' and 30' to the nose and to the temple from the center. We also studied the topography of the cornea with the help of a Scheimpflug analyzer Galilei G2 (Ziemer, Switzerland). The degree and the sign of peripheral defocus in intact eyes with myopia measured with both methods coincide fully. Refractometry taken after orthokeratological correction shows an essential myopic defocus induced by a modified corneal topography in all peripheral zones,while optical biometry revealsa hyperopic defocus which coincides with that obtained while measuring intact eyes with the same refraction. Recommendations are given on using the above methods of measuring peripheral refraction and retinal contour in different clinical situations // Russian Ophthalmological Journal, 2015; 3: 52-6.