Effect of Ocular Magnification Correction on Measurements of Macula Ganglion Cell Complex in Myopic Children.

Abstract

Optical Coherence Tomography (OCT) imaging in myopic eyes may be influenced by measurement error from axial length-induced magnification effects. We studied the effects of magnification correction on ganglion cell complex (GCL++) thickness in myopic children. Clinical cohort. Children aged 7 to 16 years in a myopic clinic. Data collected included age, gender, race, cycloplegic refraction, axial length (AL), keratometry (K), intraocular pressure (IOP), cup-to-disc ratio (CDR), optic disc tilt, peripapillary atrophy (PPA) and OCT macula scans from the right eye. GCL++ thickness in the central, inner and outer superior, inferior, nasal and temporal quadrants was measured with or without adjustments for ocular magnification using the Littmann-Bennett formula. 492 subjects, comprising 46.7% male and 91.8% Chinese with an average age of 10.3 ± 1.6 years were included in the study. Mean spherical equivalent (SE) was -4.43 ± 2.24D, and AL was 25.04 ± 1.05 mm. Multivariate analysis showed unadjusted and adjusted GCL++ thickening in older age; in the central and inner quadrants in males; and in the outer temporal quadrant in Chinese children. Central unadjusted and adjusted GCL++ were also thicker with decreased SE, flatter K and increased AL. In other quadrants, unadjusted GCL++ was thinner with decreasing SE and increasing AL in all but the nasal quadrant. Adjusted values were thicker with decreased SE, flatter K, and increasing AL (P ≤ .001 for all). IOP, CDR, optic disc tilt, PPA and myopia treatment had no effect on GCL++. Ocular magnification correction of OCT-measured retinal layer thickness using adjustments for axial length suggests increasing myopia is associated with thickening of the ganglion cell complex in children.