Characterizing Retinal Mitochondrial Function and Its Relations to Intraretinal Thicknesses in Healthy Adults.

Purpose: To characterize retinal mitochondrial function and its relationship with intraretinal thicknesses in healthy adults.

Methods: Retinal flavoprotein fluorescence (FPF), a marker of mitochondrial function, was measured using the OcuMet Beacon (OcuSciences, Inc., Ann Arbor, MI), and a stress index (SI) was computed using Enhanced Retinal Metabolic Analysis software 2.0 (RMA). After lens compensation, mean FPF in the macula and optic nerve head (ONH) was obtained. The macular SI summarizes FPF heterogeneity, while the ONH SI reflects the extent to which ONH FPF exceeds a normative threshold. Intraretinal layer thicknesses and total retinal thickness (TRT) were measured via spectral-domain OCT (AngioVue, Optovue, Inc., ver. 2018.1.0.43) using 6 x 6 mm macular scans. A total of 75 healthy adults (mean age ± SD: 56.1 ± 21.7 years; range: 23-89) were imaged.

Results: Macular and ONH FPF were inversely correlated with TRT (p < 0.01), retinal nerve fiber layer (RNFL) thickness (p < 0.05), and ganglion cell-inner plexiform layer (GCIPL) thickness (p < 0.01). ONH FPF also showed a negative correlation with the thickness of the OPL-EZ region-defined as the area between the posterior boundary of the outer plexiform layer (OPL) and the anterior boundary of the ellipsoid zone (EZ) (r = -0.24, p = 0.044)-and the photoreceptor layer (PR) (r = -0.34, p = 0.003). Age was significantly associated with FPF and with several intraretinal layer thicknesses, including TRT, RNFL, GCIPL, OPL-EZ region, and PR (all p < 0.05). However, after adjusting for age, associations between FPF and intraretinal thicknesses were no longer significant (all p > 0.05).

Conclusion: This study is the first to examine the relationship between retinal mitochondrial function and intraretinal layer thicknesses in healthy adults. Findings suggest that age mediates the observed associations.