Retinal Ganglion Cell Layer Thickness And Volume Measured By Optical Coherence Tomography Changes With Age, Sex, And Axial Length In A Healthy Population

Abstract

Background: The GCL measurements with OCT are important for both ophthalmologists and neurologist because of the association with many ophthalmic and neurological diseases. Different factors can affect these measurements, as brain pathologies, ocular AL as well as age and sex. Studies that conducted to measure GCL have overlooked many of these factors. The purpose of this study is to examine the effect of age, sex, and axial length on normal retinal GCL thickness and volume in a healthy population without any neurological diseases.Methods: A prospective cross-sectional study to measure the retinal (GCL) thickness and total volume with optical coherence tomography (OCT) with automated segmentation and manual correction where needed. Visual acuity, axial length, and autorefraction were also measured. A mixed linear model was used to determine the association of the effect of the various parameters on the GCL thickness and volume.Results: 116 eyes of 60 subjects (12-76 years of age, 55% female) were examined of which 77% had 0 ± 2 D of spherical equivalent, and mean axial length was 23.86 mm. About 25% of the OCT-automated GCL measurements required manual correction. GCL thickness did not differ in similar anatomic regions in right and left eyes (P > 0.05). GCL volume was greater in males relative to females after adjustment for age and axial length (1.13 ± 0.07 mm3 for male vs 1.09 ± 0.09 mm3 for females; P = 0.031). GCL thickness differed between males and females in the inner retinal ring (P=0.025) but not in the outer ring (P=0.66). GCL volume declined with age (P=0.031) but not after adjustment for sex and axial length (P=0.138). GCL volume declined with longer axial length after adjustment for age and sex (P=0.048). Conclusion: Age, sex and axial length should be taken into consideration when measuring the GCL thickness and volume with OCT. Automated OCT segmentation should be reviewed for manual adjustments.