Relationships between mesopic visual sensitivity and macular inner and outer retinal layer thickness in healthy younger, middle-aged and older adults.

Purpose: To examine relationships between mesopic visual sensitivity measurements on microperimetry and macular inner and outer retinal layer (IRL and ORL) thicknesses in healthy younger, middle-aged and older subjects.

Methods: In total, 154 healthy adults were divided into three age groups each with similar mean sensitivity. Regional retinal sensitivity (determined by mesopic fundus-controlled microperimetry) and IRL (ganglion cell-related layer) and ORL thicknesses were measured in the five subfields: central fovea (1 mm diameter) and the quadrants temporal, nasal, superior and inferior of a parafoveal ring of outer diameter 3 mm and inner diameter 1 mm. Relationships between regional sensitivity and corresponding IRL and ORL thicknesses were assessed through a univariate and multivariate linear regression model.

Results: Visual sensitivity means for each subfield differed across age groups (all p < 0.001). In each parafoveal ring quadrant, mean IRL thickness was reduced in the older eyes compared to the other groups (all p < 0.0001). In the inferior region, worse sensitivity was correlated with greater IRL thickness (p = 0.0207) in the middle-aged group and with a thicker ORL (p < 0.0001) and thinner IRL (p = 0.0003) in the older eyes (R = 0.51). The slopes of regression lines relating sensitivity to IRL thickness and age group (p = 0.0027) or to ORL thickness and age group (p = 0.0020) differed significantly.

Conclusions: The relationship observed between mesopic visual sensitivity and retinal layer thickness varied with age. A worse sensitivity was related to a thicker macular IRL layer in middle-aged eyes and to a thicker ORL and thinner IRL in older eyes.