Retinal thickness vs. retinal sensitivity at the central human macula

Abstract

Purpose To assess the detailed correlation between retinal thickness and retinal visual function in the central 300 µm human macular area. Methods Twenty-four eyes with clinically significant macular edema (CSME) (12 eyes with and 12 eyes without central foveal involvement) underwent retinal thickness measurement (RT) and retinal sensitivity, performed by Cirrus HD-OCT (Carl Zeiss Meditec, Dublin, CA, USA) and MP1 (Microperimetry, Nidek, Japan) systems, respectively. The average retinal thickness in the 300 µm diameter area, centered in the fovea, was computed and correlated with the central MP1 value. RT could also be locally correlated with MP1 values in areas of 30 µm in diameter centered at each stimulus site. Precise correspondence between stimuli and RT locations was ensured by bringing into co-registering the fundus image references from both modalities. Results A moderate correlation was found between RT and central MP1 value (R=-0.578, p=0.003). The correlation decreases when analysing, separately, eyes with or without central foveal involvement (p>0.05 for both groups) being stronger for the CSME eyes with central involvement. Conclusion Cirrus HD-OCT high resolution mapping allows to correlate structure and function at detailed level in the central fovea. It became possible to demonstrate the lack of direct correlation RT/MP1 and the reason why an apparent correlation exist when considering all cases of being part of the same group.