Age-Related Changes in Macular Structure Among Young and Middle-Aged Healthy Subjects Assessed by OCT Image Segmentation

Abstract

Purpose: : We previously demonstrated the usefulness of optical coherence tomography (OCT) image segmentation and quantification of the local variations of the intraretinal layers by our own custom-built algorithm. In the present study we aimed to observe age-related changes in the macular structure of healthy individuals.

Methods: : Altogether 80 eyes of 40 normal subjects were recruited in our study (35±13years [mean±SD], age range 20-65 years). All patients underwent routine ophthalmic examination with pupil dilation, followed by standard macular mapping ("Macular Thickness Map Protocol") by commercially available StratusOCT^TM (Carl Zeiss Meditec Inc., Dublin, CA, USA). Exclusion criteria were best corrected visual acuity below 1.0, eye surgery performed three months prior to examination, the presence of systemic diseases (e.g. diabetes, hypertension) or any retinal diseases. The OCT raw data were exported and analyzed using a custom-built OCT Retinal Image Analysis software (OCTRIMA). Then, thickness analysis was performed for the automatically extracted retinal layers (RNFL, GCL+IPL, INL, OPL, ONL, RPE) and average regional thickness data of all layers were recorded in the central, four inner (pericentral ring) and four outer regions (peripheral ring) and linear correlation analysis with age was performed. Because of the number of statistical analyses, the level of significance was set at p<0.0025.

Results: : A significant increase in RPE thickness was observed with age in the central and pericentral regions (p=0.0018, r=0.34 and p=0.000, r=0.50), while all other retinal layer thickness results showed no correlation with age.

Conclusions: : We could support the previously histologically described thickness increase of the RPE layer in vivo using OCT image segmentation. Interestingly, the above changes were observed only in the central and pericentral but not the peripheral parts of the macula, the reason of which remains unclear. The relatively young age of the subjects involved in the study may be responsible for detecting no significant changes in the RNFL and GCL+IPL layers where previous histological studies have shown thinning occurring with age. Because of the relatively small number of eyes involved in our study, our findings raise the need of further investigations.

Keywords: macula/fovea • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • Bruch's membrane