Iron is an essential component in many biological processes in the human body. It is critical for the visual phototransduction cascade in the retina. However, excess iron can be toxic. Iron accumulation and reduced efficiency of intracellular antioxidative defense systems predispose the aging retina to oxidative stress-induced cell death. Age-related macular degeneration (AMD) is characterized by retinal iron accumulation and lipid peroxidation. The mechanisms underlying AMD include oxidative stress-mediated death of retinal pigment epithelium (RPE) cells and subsequent death of retinal photoreceptors. Understanding the mechanism of the disruption of iron and redox homeostasis in the aging retina and AMD is crucial to decipher these mechanisms of cell death and AMD pathogenesis. The mechanisms of retinal cell death in AMD are an area of active investigation; previous studies have proposed several types of cell death as major mechanisms. Ferroptosis, a newly discovered programmed cell death pathway, has been associated with the pathogenesis of several neurodegenerative diseases. Ferroptosis is initiated by lipid peroxidation and is characterized by iron-dependent accumulation. In this review, we provide an overview of the mechanisms of iron accumulation and lipid peroxidation in the aging retina and AMD, with an emphasis on ferroptosis.

Age-related macular degeneration (AMD) causes irreversible vision-loss among the elderly in industrial countries. Neovascular AMD (nAMD), which refers to late-stage AMD, is characterized by severe vision-threatening choroidal neovascularization (CNV). Herein, we constructed a global metabolic network of nAMD, based on untargeted metabolomic and lipidomic analysis of plasma samples collected from sixty subjects (30 nAMD patients and 30 age-matched controls). Among the nAMD and control groups, 62 and 44 significantly different metabolites were detected in the positive and negative ion modes, respectively. Grouping analysis further showed that lipid and lipid-like molecule-based superclasses contained the highest number of significantly different metabolites. Lipidomic analysis revealed that 53 lipids among the nAMD and control groups differed significantly; these belonged to four major lipid categories (glycerophospholipids, sphingolipids, glycerolipids, and fatty acids). A discriminative biomarker panel comprising 16 metabolites and lipids, which was constructed using multivariate statistical machine learning methods, could effectively identify nAMD cases. Among these 16 compounds, eight were lipids that belonged to three lipid categories (glycerophospholipids, sphingolipids, and prenol lipids). The top three biomarkers with the highest importance scores were all lipids (a glycerophospholipid and two sphingolipids), highlighting the crucial role played by glycerophospholipid and sphingolipid pathways in nAMD. These differences between the metabolic and lipid profiles of nAMD patients and elderly individuals without AMD provide a readout of the overall metabolic status of nAMD. Further insights into the identified discriminative biomarkers may pave the way for future diagnostic and therapeutic interventions for nAMD.

To compare short-term anatomical outcomes observed in optical coherence tomography (OCT) between intravitreal injection (IVI) with anti-vascular endothelial growth factor (VEGF) agent aflibercept (IVA) and subthreshold micropulse laser (SML) therapy in chronic central serous chorioretinopathy (cCSC). Thirty-nine eyes of 36 patients with symptomatic cCSC in this retrospective study received either IVA or SML between December 2020 and August 2022. Spectral-domain-OCT (SD-OCT) findings were compared between the two treatment groups in terms of central macular thickness (CMT), serous subretinal fluid (SRF) height, the presence of pigment epithelial detachment (PED) and subretinal hyperreflective foci (HF) at baseline and one-month follow-up visits. Both groups showed significant reductions in CMT and SRF at one-month follow-up visit. However, there were no statistically significant differences between the IVA and SML groups. Complete SRF resolution was observed in 10 out of 21 and 7 out of 18 eyes in the IVA and SML groups, respectively; however, retinal pigment epithelial (RPE) damage remained persistent in patients with PEDs at baseline. Both IVA and SML were effective in treating cCSC. IVA and SML treatments had comparable effects in reducing CMT and SRF in eyes with cCSC. Further prospective studies with larger sample sizes and long-term follow-up visits are warranted to identify the long-term efficacy.