Variations of OCT measurements corrected for the magnification effect according to axial length and refractive error in children

Abstract

Purpose: The aim of this paper was to examine the distribution of macular, retinal nerve fiber layer (RNFL) thickness and optic disc parameters of myopic and hyperopic eyes in comparison with emmetropic control eyes and to investigate their variation according to axial length (AL) and spherical equivalent (SE) in healthy children. Methods: This study included 293 pairs of eyes of 293 children (145 boys and 148 girls), ranging in age from 6 to 17 years. Subjects were divided according to SE in control (emmetropia, 99 children), myopia (100 children) and hyperopia (94 children) groups and according to axial AL in 68 short ([Formula: see text]22.00[Formula: see text]mm, 68), medium (from [Formula: see text]22.00[Formula: see text]mm to 25.00[Formula: see text]mm, 189) and long eyes ([Formula: see text]25.00[Formula: see text]mm, 36). Macular parameters, RNFL thickness and optic disc morphology were assessed by the CirrusTM HD-OCT. AL was measured using the IOL-Master system. Littmann’s formula was used for calculating the corrected AL-related ocular magnification. Results: Mean age ([Formula: see text][Formula: see text]SD) was 10.84[Formula: see text][Formula: see text][Formula: see text]3.05 years; mean ([Formula: see text][Formula: see text]SD) SE was [Formula: see text]0.14[Formula: see text][Formula: see text][Formula: see text]0.51 D (range from [Formula: see text]8.75 to [Formula: see text]8.25 D) and mean AL ([Formula: see text][Formula: see text]SD) was 23.12[Formula: see text][Formula: see text][Formula: see text]1.49. Average RNFL thickness, average macular thickness and macular volume decreased as AL and myopia increased. No correlations between AL/SE and optic disc parameters were found after correcting for magnification effect. Conclusions: AL and refractive error affect measurements of macular and RNFL thickness in healthy children. To make a correct interpretation of OCT measurements, ocular magnification effect should be taken into account by clinicians or OCT manufacturers.