Influence of Age, Race and Image Quality on Spectral Domain Optical Coherence Tomography (SDOCT) based measures of the Ganglion Cell Layer (GCL), Macular Thickness (MT), Retinal Nerve Fiber Layer (RNFL) and Neuroretinal Rim Area in healthy adult eyes

Abstract

Purpose: : To determine how age, race and image quality affect the ganglion cell layer (GCL) thickness, macular thickness, retinal nerve fiber layer (RNFL) thickness, and neuroretinal rim area in healthy adult eyes measured using SDOCT.

Methods: : In a cross-sectional study, Cirrus SDOCT (Carl Zeiss Meditec) was used to collect optic nerve head images from 121 healthy adults of African descent (AD, 106 eyes) and European descent (ED, 122 eyes) and macular images from 74 healthy adults (AD 95 eyes, ED 49 eyes). Participants were from the Diagnostic Innovations in Glaucoma Study (DIGS) and African Descent and Glaucoma Evaluation Study (ADAGES). All eyes had a normal appearance of the optic disc by stereophotograph assessment, an intraocular pressure lower than 22 mmHg, and no repeatable visual field damage. The effects of age, race and image quality, defined as signal strength, on GCL, macular and RNFL thickness and neuroretinal rim area were determined using univariate and multivariate linear mixed models.

Results: : In univariate analysis, with increasing age, there was a significant decrease in average RNFL thickness of 0.19µm/year (p=0.002) and a decrease in average GCL thickness of 0.18 µm/year (p=0.002). In addition, we found that superior, inferior, and nasal macular thickness significantly decreased with increasing age. Age was not significantly associated with rim area in univariate analysis. Signal strength was positively associated with RNFL thickness, but not with GCL or macular thickness. AD participants had significantly larger disc areas (p = 0.026) and thinner inner macular thickness than ED participants.

Conclusions: : In this cross-sectional study of normal subjects, there was a strong association between age and ganglion cell layer thickness, macular thickness and RNFL thickness regardless of race. Clinicians need to consider the associations between age, RNFL, and GCL thickness to help differentiate between normal changes due to aging and glaucomatous progression.

Clinical Trial: : http://www.clinicaltrials.gov NCT00221897

Keywords: imaging/image analysis: clinical