Abstract
Purpose :
age related lipofuscin accumulation within retinal pigment epithelium (RPE) cells has been demonstrated in healthy subjects in vivo using quantitative fundus autofluorescence (qAF). The aim of this study was to investigate the possible correlation existing between the RPE thickness and the qAF values in a healthy Caucasian population.
Methods :
Healthy volunteers between 18 and 65 years of age were enrolled. All subjects underwent Spectral Domain Optical Coherence Tomography (SD-OCT) and qAF (Heidelberg Spectralis) imaging. SD-OCT images were analyzed using the built-in graph-based automatic segmentation algorithm for single retinal layers identification to assess RPE thickness. Only values within central and overall intermediate ETDRS grid were considered for the analysis. Using a customized dedicated software, qAF images were also evaluated and values of eight subfields forming a ring centered onto the fovea were collected and averaged in order to obtain a single qAF value (qAF8).
The correlation between the RPE thickness (RPEt) in the central and intermediate ETDRS ring and the age of the subjects was assessed. The effect of qAF and age on the RPEt was studied with a multivariate regression analysis.
Results :
A total of 105 eyes from 105 subjects (mean age 42.1±13.9 years) were included in the analysis. The RPEt significantly increased with age in the intermediate ETDRS ring (r=0.29,P<0.05). The values of qAF were also positively correlated with age (r=0.68,P<0.05). A significant correlation was found between qAF and RPEt, However, after adjusting for age in the multivariate regression model, the correlation remained significant only for subjects younger than 40 years of age (P<0.05).
Conclusions :
The RPEt increased with age in a healthy population. A similar increase was found for qAF values. After adjusting for age, qAF and RPEt were still correlated in subjects younger than 40 years. Since qAF indirectly measures the lipofuscin amount within the RPE, the thickening of the RPE measured in vivo with OCT is likely correlated with lipofuscin accumulation. These findings could help in understanding the pathophysiology of a variety of diseases determined by lipofuscin damage to the RPE.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.