Table 2.
Summary of key findings associating oxidative stress with pathologies affecting the anterior and posterior segments of the eye (Abbreviations: electron transport chain (ETC); reduced glutathione (GSH); 4-hydroxynonenal (4-HNE); malondialdehyde (MDA); nuclear factor-erythroid 2 related factor 2 (NRF2); 8-hydroxy-2-deoxyguanosine (8-OHdG); retinal ganglion cells (RGCs); retinal pigment epithelium (RPE); superoxide dismutase (SOD); tricarboxylic acid (TCA)).
| Condition | Clinical Manifestation(s) | Identified Markers of Oxidative Stress | Ref. |
|---|---|---|---|
| Dry eye disease | Instability of the lipid layer, decreased tear secretion, ocular irritation | Elevated 8-OHdG, 4-HNE, and MDA and higher immune infiltration in dry eye animal models; elevated 4-HNE and hexanoyl-lysine in the conjunctiva of patients with dry eye and Sjögren’s syndrome | [42,43,45] |
| Keratoconus | Thinning of the corneal stroma leading to bulging of the central cornea | Elevated lipid peroxidation, MDA, and proinflammatory cytokines in tears of patients with keratoconus; increased lactate production and altered glycolytic and TCA cycle metabolite levels in corneal fibroblasts; decreased NRF2 expression | [64,65,66,67] |
| Cataract | Opacification of the lens | Oxidation, deamidation, and other chemical modifications of crystallin proteins, leading to protein aggregation and precipitation; decreased GSH in lens epithelial cells | [117,121,138] |
| Age-related macular degeneration | Drusen formation and photoreceptor degeneration; choroidal neovascularization, hemorrhage, and retinal fibrosis | Elevated MDA and 8-OHdG; decreased SOD in RPE cells; elevated carboxyethylpyrrole in drusen | [221,225,233] |
| Proliferative vitreoretinopathy | Formation of fibrotic membranes on the retinal surface | Reduced SOD and catalase in vitreous; decreased GSH in vitreous and blood | [283,284] |
| Diabetic retinopathy | Vascular abnormalities in the retina; microaneurysms, hemorrhaging, and angiogenesis | Increased ROS production by ETC with hyperglycemia; decreased SOD, catalase, and GSH production | [321,322,329] |
| Glaucoma | Loss of RGCs in the retina | Reduced total reactive antioxidant potential and increased MDA in the aqueous humor and blood | [381,382,424] |