Relationship Between Flicker Modulation Sensitivity and Retinal Ganglion Cell Related Layer Thicknesses

Abstract

Purpose Early detection of structural changes in retinal ganglion cells (RGCs) and corresponding changes in visual function is important in early degenerative diseases of the retina, but the sensitivity of both measurements is limited by the inherent variability in healthy subjects. This study investigates the relationships between RGC-related layer thicknesses and foveal and parafoveal flicker modulation sensitivity (FMS) across photopic and mesopic light levels in healthy subjects. Methods Photopic and mesopic FMS was measured in 56 young adults, at the point of fixation and at an eccentricity of 5 degrees, in each of the four quadrants. Spectral-domain optical coherence tomography (SD-OCT) was used to measure retinal thicknesses. Relationships between foveal and parafoveal FMS and the retinal thickness in the corresponding region were examined after adjusting for confounding variables. Results Total macular and inner retinal layer (IRL) thicknesses in the parafoveal ring were significant predictors of photopic ( P = 0.034) and mesopic ( P = 0.034) parafoveal FMS, respectively. The superior peripapillary retinal nerve fiber layer (pRNFL) thickness was a contributing factor to the inferior parafoveal FMS (photopic: P = 0.006 and mesopic: P = 0.021) and the inferior pRNFL thickness was also a contributing factor to the superior parafoveal FMS (photopic: P < 0.001 and mesopic: P = 0.015). Conclusions The pRNFL thicknesses predict parafoveal FMS for both mesopic and photopic conditions in healthy eyes. Translational Relevance The measurement of rapid flicker sensitivity in the parafoveal retina together with the pRNFL thickness profiles measured before the onset of disease, may provide a more sensitive biomarker for detecting loss of sensitivity caused by the earliest neurodegenerative changes in the eyes.

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

“…While so far several studies have examined how modifications in retinal morphology determined by spectral domain optical coherence tomography (SD-OCT) correlate with visual function in AMD (Schmidt-Erfurth & Waldstein, 2016) and glaucoma (Yohannan & Boland, 2017), this issue has hardly been addressed in healthy subjects. In young and older healthy eyes, structure-function relationships have been detected between retinal layer thicknesses and contrast sensitivity (Puell et al, 2018), mesopic visual acuity and low-luminance deficit (Puell et al, 2019) and flicker modulation sensitivity (Pérez-Carrasco et al, 2021). Hence, information about retinal structure-function relationships at different ages in healthy eyes may be useful to elucidate the mechanisms behind the loss of visual function caused by aging.…”