This study used targeted metabolomics to examine metabolic differences across retinal regions and tissues in human donor eyes, focusing on the macula versus peripheral neural retina and the underlying RPE/choroid. The authors quantified 133 metabolites in paired macular and peripheral neural retina and RPE/choroid explants following short-term culture intended to restore metabolic activity.
Paired explants from human donor eyes were cultured briefly to re-establish metabolic activity and then analyzed using targeted metabolomics. A total of 133 metabolites were quantified in matched samples from the macular and peripheral neural retina and the corresponding RPE/choroid. The short-term culture step and paired sampling design enabled direct regional and tissue comparisons while controlling for donor-specific variables.
Compared with the peripheral neural retina, the macula exhibited metabolic features consistent with elevated glycolytic activity and increased availability of reduced nicotinamide cofactors. The macular neural retina showed higher indications of NADH availability and elevated concentrations of neurotransmitter-associated metabolites, specifically N-acetyl-aspartate (NAA) and N-acetyl-aspartyl-glutamate (NAAG). These metabolite patterns are interpreted as consistent with increased energetic and neuronal activity in the cone-rich macula relative to the rod-rich periphery.
The combination of greater glycolytic signatures and higher levels of NAA and NAAG suggests that the macula has both enhanced energy production pathways and increased neurotransmitter-related metabolism, aligning with its known high functional demand.
Metabolite measurements in the RPE/choroid revealed regional differences as well. The macular RPE/choroid contained higher levels of the flavin cofactor FAD and several NAD-related metabolites, including NAD, NADP, and NAAD, when compared with peripheral RPE/choroid. These differences indicate a regionally distinct cofactor and redox state within the supporting RPE/choroid layer beneath the macula.
Elevated FAD and NAD-related metabolites in macular RPE/choroid may reflect increased cofactor-dependent metabolic processes in the macular support tissue, potentially matching or supporting the higher energetic requirements of the overlying macular neural retina.
Across tissues, the neural retina and RPE/choroid exhibited distinct functional metabolic associations. The neural retina’s metabolic profile was primarily associated with energy production and neurotransmission, consistent with the high energetic demands of photoreceptors and synaptic activity. In contrast, the RPE/choroid profile was linked to cofactor metabolism, nucleotide salvage, and lipid metabolism, reflecting roles in metabolic support, maintenance of redox balance, and substrate handling for the neural retina.
These complementary metabolic specializations are consistent with a model of metabolic coupling between the neural retina and RPE/choroid, where each tissue performs distinct but interdependent biochemical functions to sustain retinal physiology.
The macula’s metabolic pattern—greater glycolytic activity, higher NADH availability, and increased levels of neurotransmitter-associated metabolites—indicates an elevated energetic and neuronal workload in this region. Similarly, macular RPE/choroid shows increased levels of key redox cofactors (FAD, NAD, NADP, NAAD) that may reflect compensatory or supportive metabolic processes.
Together, these observations provide a potential metabolic basis for the macula’s selective vulnerability in macular diseases: higher intrinsic energetic demand and distinctive cofactor requirements could render macular cells more susceptible to metabolic stress or perturbation. The study’s findings support further investigation into regional metabolic vulnerabilities as contributors to macular pathology.
The content summarized here is drawn from the article abstract. Specific experimental details, including the number of donor eyes analyzed, exact culture conditions, statistical methods, and full metabolite lists or quantitative results, were not reported in the abstract. The article is a preprint and has not undergone peer review.
These results generate testable hypotheses about regional retinal metabolism and the metabolic interplay between neural retina and RPE/choroid that warrant detailed follow-up with full methods and peer-reviewed reporting.