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

Abstract

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 presented.)22.00(Formula presented.)mm, 68), medium (from (Formula presented.)22.00(Formula presented.)mm to 25.00(Formula presented.)mm, 189) and long eyes ((Formula presented.)25.00(Formula presented.)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 presented.)(Formula presented.)SD) was 10.84(Formula presented.)(Formula presented.)(Formula presented.)3.05 years; mean ((Formula presented.)(Formula presented.)SD) SE was (Formula presented.)0.14(Formula presented.)(Formula presented.)(Formula presented.)0.51 D (range from (Formula presented.)8.75 to (Formula presented.)8.25 D) and mean AL ((Formula presented.)(Formula presented.)SD) was 23.12(Formula presented.)(Formula presented.)(Formula presented.)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.