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Oxidative Stress Pathways from High Sugar Exposure: Nrf2, Mitochondria, and RGC Survival · Glaucoma, Vision & Longevity: Supplements & Science

• 0:00
  SPEAKER_00: Oxidative stress pathways from high sugar exposure, NRF2, mitochondria, and retinal ganglion cell survival.
• 0:07
  SPEAKER_00: Introduction.
• 0:08
  SPEAKER_00: High sugar exposure is often discussed as though it has one simple effect on the eye.
• 0:12
  SPEAKER_00: The biology is more complicated.
• 0:14
  SPEAKER_00: In experimental studies, elevated Dglucose can increase reactive oxygen species, disrupt mitochondrial energy production, alter antioxidant defenses, activate retinal glial cells, and promote retinal ganglion cell injury.
• 0:28
  SPEAKER_00: Most of the evidence comes from two types of research.
• 0:31
  SPEAKER_00: Cell culture studies, in which retinal cells are exposed to glucose concentrations commonly ranging from 20 to 40 millimoles per liter, sometimes for several days.
• 0:41
  SPEAKER_00: Diabetic animal models, in which chronic hyperglycemia occurs together with vascular dysfunction, inflammation, lipid abnormalities, advanced glycation products, and tissue hypoxia.
• 0:53
  SPEAKER_00: These models do not prove that one high sugar meal directly kills retinal ganglion cells.
• 0:58
  SPEAKER_00: They do, however, support a biological pathway in which persistent or repeated hyperglycemia increases oxidative pressure and reduces the ability of ocular cells to recover.
• 1:09
  SPEAKER_00: The most consistent model is high glucose, increased reactive oxygen and nitrogen species, mitochondrial stress and impaired energy production, inadequate nuclear factor erythroid II-related factor II antioxidant activity, inflammation, glial reactivity, and retinal ganglion cell apoptosis.
• 1:28
  SPEAKER_00: The strength of each link varies by cell type, glucose concentration, exposure time, and whether the experiment involves diabetes, glaucoma-related stress, or isolated high glucose.
• 1:39
  SPEAKER_00: The central redox system, reactive oxygen species, and nuclear factor erythroid II-related factor II.
• 1:45
  SPEAKER_00: Reactive oxygen species are chemically reactive oxygen-containing molecules.
• 1:50
  SPEAKER_00: In small amounts, they participate in normal cell signaling.
• 1:54
  SPEAKER_00: When their production exceeds antioxidant capacity, they can oxidize proteins, membrane lipids, mitochondrial DNA, and other cellular structures.
• 2:02
  SPEAKER_00: The main protective pathway discussed in this context is controlled by nuclear factor erythroid II-related factor II, commonly called NRF2.
• 2:11
  SPEAKER_00: Under resting conditions, NRF-2 is held in the cytoplasm by Kelch-like ECH-associated protein 1, or KEAP-1, which promotes its degradation.
• 2:21
  SPEAKER_00: When oxidative stress is sensed, NRF-2 can stabilize, move into the nucleus, and stimulate antioxidant response genes.
• 2:28
  SPEAKER_00: These include genes involved in glutathione production, superoxide removal, hydrogen peroxide breakdown, thyroidoxin recycling, and detoxification.
• 2:37
  SPEAKER_00: Important in RF2 regulated defenses in retinal cells include glutamate cysteine ligase, which supports glutathione production, superoxide dismutase 2, a mitochondrial antioxidant enzyme, catalase, thyroidxin heme oxygenase 1, NADPH quinone oxidorductase 1.
• 2:55
  SPEAKER_00: A key finding across the literature is that high glucose does not always completely turn off NRF2.
• 3:00
  SPEAKER_00: Instead, the response may be delayed, transient, cell-specific, or insufficient for the amount of oxidative stress produced.
• 3:08
  SPEAKER_00: How high glucose increases oxidative stress in ocular cells, increased metabolic pressure.
• 3:14
  SPEAKER_00: Retinal neurons and glial cells are metabolically active.
• 3:18
  SPEAKER_00: When excess glucose enters the cell, more carbon is directed through glycolysis and mitochondrial energy pathways.
• 3:25
  SPEAKER_00: This can increase the supply of reducing equivalents to the mitochondrial respiratory chain.
• 3:30
  SPEAKER_00: If electron transport becomes overloaded or poorly coordinated, electrons can leak and generate superoxide.
• 3:37
  SPEAKER_00: Experimental retinal studies have also identified non-mitochondrial contributors, including activation of nicotinamide adenine dinucleotide phosphate oxidase, increased inflammatory signaling through nuclear factor kappa B, thioridoxin interacting protein induction, nitric oxide and reactive nitrogen species production, disruption of glutathione and antioxidant enzyme systems, in Miller-glial cells, high glucose increased reactive oxygen species within hours and increased reactive nitrogen species even earlier.
• 4:09
  SPEAKER_00: The same study found increased nuclear factor kappa B signaling and increased inducible nitric oxide synthase, linking redox imbalance to inflammation.
• 4:19
  SPEAKER_00: Oxidative stress can become self-reinforcing.
• 4:21
  SPEAKER_00: Mitochondria are both a source and a target of reactive oxygen species.
• 4:26
  SPEAKER_00: Once mitochondrial proteins, membranes, or mitochondrial DNA are damaged, the respiratory chain may become less efficient.
• 4:33
  SPEAKER_00: This can produce still more oxidant leakage, creating a feedback loop.
• 4:38
  SPEAKER_00: High glucose, mitochondrial stress, more reactive oxygen species, further mitochondrial damage.
• 4:45
  SPEAKER_00: In Miller cells, high glucose increased mitochondrial superoxide disrupted mitochondrial membrane potential and increased the mitochondrial localization of thioridoxin interacting protein.
• 4:57
  SPEAKER_00: These changes were associated with mitochondrial dysfunction and impaired mitochondrial quality control.
• 5:03
  SPEAKER_00: Evidence for glucose-induced mitochondrial dysfunction, Miller glial cells.
• 5:08
  SPEAKER_00: One of the clearest mitochondrial studies used a rat Miller cell line exposed to 30 millimoles per liter glucose for seven days.
• 5:16
  SPEAKER_00: High glucose caused mitochondrial fragmentation, greater variation in mitochondrial membrane potential, lower basal and maximal oxygen consumption, lower extracellular acidification, cytochrome C release, increased apoptosis.
• 5:32
  SPEAKER_00: These findings are important because they connect mitochondrial structural changes with functional failure and cell death rather than merely showing an increase in a laboratory oxidative stress marker.
• 5:43
  SPEAKER_00: A related study found that high glucose increased thioredoxin interacting protein, mitochondrial superoxide, and mitochondrial membrane potential abnormalities in rat Miller cells.
• 5:55
  SPEAKER_00: The changes were accompanied by impaired mitophagy, the process that removes damaged mitochondria.
• 6:01
  SPEAKER_00: More recent work suggests that mitochondrial remodeling is not always the same in every stage of disease.
• 6:08
  SPEAKER_00: Under diabetic conditions, Miller cells may initially use mitochondrial fragmentation as an adaptive response to remove damaged segments.
• 6:17
  SPEAKER_00: In more advanced neurodegeneration, mitochondrial hyperfusion and defective turnover may develop instead.
• 6:23
  SPEAKER_00: This means that mitochondrial shape alone cannot be interpreted without considering exposure duration and disease stage.
• 6:31
  SPEAKER_00: Retinal ganglion cells.
• 6:33
  SPEAKER_00: Retinal ganglion cells are especially vulnerable to mitochondrial stress because they have long axons and substantial energy requirements.
• 6:41
  SPEAKER_00: In high glucose retinal ganglion cell models, investigators have reported increased reactive oxygen species, loss or abnormality of mitochondrial membrane potential, cytochrome C release, reduced antioxidant enzyme activity, increased B cell lymphoma II associated X-protein and Caspace signaling, increased terminal deoxynucleotid transferase DUTP nic-n labeling, a marker of DNA fragmentation, reduced cell survival.
• 7:08
  SPEAKER_00: In one study, L-carnitine, a mitochondrial supporting molecule, reduced glucose-induced reactive oxygen species and lipid peroxidation.
• 7:16
  SPEAKER_00: It also restored mitochondrial membrane potential, reduced cytochrome C release, lowered Casbase-9 and Casp3 activation, and shifted the B cell lymphoma-2 associated X protein to B cell lymphoma-2 balance toward cell survival.
• 7:31
  SPEAKER_00: A 2024 study using a retinal precursor cell model and diabetic mice found that high glucose or diabetes was associated with mitochondrial dysfunction, reactive oxygen species production, abnormal antioxidant protein expression, and retinal ganglion cell apoptosis.
• 7:48
  SPEAKER_00: Increasing DJ1, a protein involved in mitochondrial protection and redox control, improved mitochondrial function and reduced oxidative injury.
• 7:58
  SPEAKER_00: Mitochondrial DNA damage.
• 8:00
  SPEAKER_00: Mitochondrial DNA is located close to the respiratory chain and has less protection than nuclear DNA.
• 8:06
  SPEAKER_00: A recent retinal ganglion cell study reported that high glucose was associated with mitochondrial structural abnormalities, increased reactive oxygen species, abnormal mitochondrial membrane potential, lower oxygen consumption, lower adenosine triphosphate production, and mitochondrial DNA damage.
• 8:25
  SPEAKER_00: The authors also observed reduced expression of proteins involved in DNA damage repair.
• 8:30
  SPEAKER_00: These results support a model in which mitochondrial damage is not simply a consequence of apoptosis.
• 8:36
  SPEAKER_00: It may occur early enough to contribute to the decision of a retinal ganglion cell to enter an apoptotic pathway.
• 8:43
  SPEAKER_00: Evidence for impaired or inadequate NRF-2 antioxidant responses.
• 8:48
  SPEAKER_00: A transient NRF-2 failure in Miller cells.
• 8:51
  SPEAKER_00: A detailed time course study exposed primary rat Miller cells to 25 millimoles per liter glucose for 1 to 48 hours.
• 8:59
  SPEAKER_00: The findings show why the phrase NRF-2 impairment needs to be used carefully.
• 9:04
  SPEAKER_00: Reactive oxygen species increased from approximately 12 to 48 hours.
• 9:09
  SPEAKER_00: Reactive nitrogen species rose earlier.
• 9:12
  SPEAKER_00: NRFF2 protein and nuclear NRF2 temporarily decreased after approximately 3 hours.
• 9:18
  SPEAKER_00: Glutamate cysteine ligase, superoxide dismutase 2, and thioridoxin messenger RNA fell during the early exposure period.
• 9:25
  SPEAKER_00: Glutathione remained low even after some NRF-2 measures recovered.
• 9:29
  SPEAKER_00: NRF2 and several antioxidant genes increased later, suggesting a delayed compensatory response.
• 9:36
  SPEAKER_00: Thus, high glucose produced an early window in which oxidative stress increased while the NRF-2 antioxidant program was temporarily weakened.
• 9:44
  SPEAKER_00: The later increase in NRF-2 did not immediately restore glutathione or antioxidant function.
• 9:51
  SPEAKER_00: This pattern is better described as delayed and inadequate antioxidant adaptation rather than permanent NRF-2 shutdown.
• 9:58
  SPEAKER_00: NRF2 is protective in diabetic retinopathy, but activation may not be sufficient.
• 10:04
  SPEAKER_00: In diabetic mice, NRF2 moved into the nucleus, indicating that diabetes activated an endogenous antioxidant response.
• 10:11
  SPEAKER_00: However, mice lacking NRF2 developed higher retinal superoxide, lower glutathione, higher tumor necrosis factor alpha, earlier blood retina barrier dysfunction, and greater visual dysfunction.
• 10:23
  SPEAKER_00: Interestingly, after eight weeks of diabetes, the investigators did not observe widespread retinal apoptosis in either normal or NRF-2 deficient mice.
• 10:33
  SPEAKER_00: This suggests that functional neuronal impairment can precede obvious cell loss.
• 10:38
  SPEAKER_00: The implication is important.
• 10:40
  SPEAKER_00: NRF-2 activation during diabetes may represent an emergency defense response, but it may not be strong enough, sustained enough, or properly coordinated to fully protect retinal neurons.
• 10:52
  SPEAKER_00: NRF-2 can protect retinal ganglion cells directly.
• 10:55
  SPEAKER_00: In primary mouse retinal ganglion cells exposed to high glucose, the NRF2 activator MIN-417 disrupted the ket1 NRF2 interaction, stabilized NRF-2, increased hemoxygenase-1 and NAPH quinone oxidoroductase 1, and reduced reactive oxygen species, cytotoxicity, and apoptosis.
• 11:14
  SPEAKER_00: The causal evidence was particularly strong.
• 11:17
  SPEAKER_00: NRF2 silencing or genetic deletion abolished the protective effect.
• 11:22
  SPEAKER_00: This shows that NRF-2 is not merely correlated with retinal ganglion cell survival, it can be functionally necessary for protection against high glucose oxidative injury in this experimental model.
• 11:34
  SPEAKER_00: Retinal astrocytes and optic nerve head astrocytes.
• 11:38
  SPEAKER_00: High glucose changes the phenotype of retinal astrocytes.
• 11:41
  SPEAKER_00: Direct studies of high glucose in retinal astrocytes show a mixed pattern.
• 11:46
  SPEAKER_00: Mouse retinal astrocytes, exposed to approximately 40.7 millimoles per liter glucose for five days developed increased reactive oxygen species, higher interleukin-1 beta and tumor necrosis factor alpha, increased glial fibrillary acidic protein, increased nuclear factor kappa B signaling, reduced migration, altered adhesion and proliferation, reduced support of endothelial capillary formation.
• 12:11
  SPEAKER_00: However, these cells did not show a major increase in apoptosis.
• 12:15
  SPEAKER_00: Instead, they increased nuclear NRF2 and antioxidant proteins such as heme oxygenase 1 and peroxyrodoxin II.
• 12:23
  SPEAKER_00: Antioxidant treatment with N-acetylcysteine improved some of the functional defects.
• 12:28
  SPEAKER_00: This is an example of reactive but relatively protected glia.
• 12:33
  SPEAKER_00: The cells became dysfunctional and inflammatory without immediately dying, probably because their NRF-2 response remained active.
• 12:41
  SPEAKER_00: Direct evidence in optic nerve head astrocytes is more limited.
• 12:45
  SPEAKER_00: The optic nerve head contains astrocytes that support retinal ganglion cell axons, regulate the local extracellular environment, and respond to mechanical and oxidative injury.
• 12:56
  SPEAKER_00: Direct studies exposing optic nerve head astrocytes to high glucose are much less developed than studies of retinal Miller cells or retinal astrocytes.
• 13:06
  SPEAKER_00: Nevertheless, non-diabetic optic nerve head studies demonstrate that oxidative stress can produce glutathione depletion, increased NRF-2 expression, increased glutamate cysteine ligase, increased glutathione S transferase, increased aldoketorctase activity, nuclear factor kappa B and CFOS activation, mitochondrial mass loss and altered mitochondrial structure.
• 13:28
  SPEAKER_00: In human optic nerve head astrocytes, the lipid peroxidation product for hydroxy non-inale caused a dose and time-dependent oxidative response.
• 13:37
  SPEAKER_00: The astrocytes initially lost glutathione but then increased CRIZF2 and antioxidant enzymes.
• 13:43
  SPEAKER_00: This demonstrates that optic nerve head astrocytes have an inducible antioxidant defense, but also that the defense system can be temporarily depleted during oxidative stress.
• 13:53
  SPEAKER_00: Another study found that oxidative stress activated optic nerve head astrocytes and increased superoxide dismutase 2 and hemoxygenase 1.
• 14:03
  SPEAKER_00: Coenzyme Q10 preserved mitochondrial mass, mitochondrial cristace structure, and bioenergetic function.
• 14:10
  SPEAKER_00: How reactive astrocytes could affect retinal ganglion cells.
• 14:14
  SPEAKER_00: Astrocyte reactivity is not automatically harmful.
• 14:17
  SPEAKER_00: Some reactive responses are protective and help restore tissue homeostasis.
• 14:21
  SPEAKER_00: However, prolonged or excessive reactivity can alter.
• 14:25
  SPEAKER_00: Glutamate handling, potassium buffering, metabolic support, extracellular matrix composition, cytokine release, antioxidant delivery, axon supporting signals.
• 14:36
  SPEAKER_00: In an experimental retinal ischemia reperfusion model, nuclear factor kappa B activation in astrocytes increased phagocyte NADPH oxidase activity and reactive oxygen species.
• 14:47
  SPEAKER_00: Suppressing this pathway reduced retinal ganglion cell loss in co-culture and in vivo experiments.
• 14:52
  SPEAKER_00: Although this was not a high glucose model, it provides evidence that oxidatively stressed reactive glia can damage retinal ganglion cells through a non-cell autonomous mechanism.
• 15:03
  SPEAKER_00: The most cautious interpretation is therefore, high glucose clearly alters retinal astrocytes and Miller cells.
• 15:11
  SPEAKER_00: It is biologically plausible that the same oxidative burden contributes to optic nerve head astrocyte reactivity, but direct high glucose optic nerve head astrocyte to retinal ganglion cell studies remain limited.
• 15:24
  SPEAKER_00: Linking oxidative stress to retinal ganglion cell apoptosis.
• 15:28
  SPEAKER_00: The evidence supports several connected routes from glucose exposure to retinal ganglion cell loss.
• 15:33
  SPEAKER_00: Oxidant accumulation.
• 15:35
  SPEAKER_00: High glucose increases cellular and mitochondrial reactive oxygen species.
• 15:39
  SPEAKER_00: Reactive nitrogen species may increase even earlier than oxygen-derived oxidants in Miller cells.
• 15:45
  SPEAKER_00: This can damage membrane lipids, proteins, antioxidant enzymes, and mitochondrial DNA.
• 15:52
  SPEAKER_00: Antioxidant reserve becomes inadequate.
• 15:54
  SPEAKER_00: Glutathione, catalase, superoxide dismutase, and thioridoxin systems may fall during early or sustained high glucose exposure.
• 16:02
  SPEAKER_00: NRF2 may be activated later, but the response may not restore antioxidant capacity quickly enough.
• 16:08
  SPEAKER_00: Mitochondrial energy failure.
• 16:11
  SPEAKER_00: Mitochondrial fragmentation, membrane potential abnormalities, reduced oxygen consumption, impaired adenosine triphosphate production, and defective mitochondrial clearance reduce the cell's ability to maintain axonal transport and ion balance.
• 16:26
  SPEAKER_00: Mitochondrial apoptotic signaling.
• 16:28
  SPEAKER_00: Mitochondrial membrane injury allows cytochrome C to move into the cytoplasm.
• 16:33
  SPEAKER_00: This activates Caspase IX and Caspase III, while pro-apoptotic B cell lymphoma 2 associated X protein increases, and antiapoptotic B cell lymphoma 2 becomes less effective.
• 16:44
  SPEAKER_00: These events are directly associated with high glucose retinal ganglion cell injury in cell models.
• 16:51
  SPEAKER_00: Glial and inflammatory amplification.
• 16:53
  SPEAKER_00: Reactive Miller cells and astrocytes can release inflammatory mediators and alter metabolic support.
• 16:59
  SPEAKER_00: This may expose retinal ganglion cells and their axons to a more hostile extracellular environment, even when the glial cells themselves remain alive.
• 17:08
  SPEAKER_00: Diabetic versus non-diabetic contexts.
• 17:11
  SPEAKER_00: Diabetic context.
• 17:13
  SPEAKER_00: Diabetes adds several factors that are usually absent from a simple glucose exposure experiment.
• 17:18
  SPEAKER_00: Chronic hyperglycemia, glucose variability, dyslipidemia, advanced glycation products, microvascular dysfunction, reduced tissue oxygen delivery, inflammation, abnormal blood retina barrier function, possible interaction with elevated intraocular pressure.
• 17:35
  SPEAKER_00: In diabetic mice, NRF2 activation appears to be a compensatory defense, but NRF2 deficiency worsens oxidative stress and visual dysfunction.
• 17:43
  SPEAKER_00: In a glaucoma-prone mouse model, diabetes also worsened retinal ganglion cell degeneration, oxidative stress, inflammation, glial reactivity, and cell death independently of intraocular pressure.
• 17:56
  SPEAKER_00: This suggests that diabetes may lower the threshold at which other stresses, such as elevated intraocular pressure, impaired perfusion, or age-related mitochondrial damage, become harmful.
• 18:07
  SPEAKER_00: Non-diabetic high glucose context.
• 18:10
  SPEAKER_00: High glucose cell culture studies show that glucose itself can produce oxidative and mitochondrial changes even without diabetes.
• 18:18
  SPEAKER_00: This is useful for isolating the direct effect of glucose, but it has limitations.
• 18:22
  SPEAKER_00: The glucose concentration may be far above typical human exposure.
• 18:26
  SPEAKER_00: Cells are exposed continuously rather than intermittently.
• 18:30
  SPEAKER_00: The experiment may last hours or days rather than years.
• 18:34
  SPEAKER_00: Cultured cells lack normal blood flow, immune regulation, and tissue architecture.
• 18:40
  SPEAKER_00: Immortalized cell lines can respond differently from primary human cells.
• 18:44
  SPEAKER_00: In non-diabetic glaucoma or optic nerve injury, oxidative stress and astrocyte reactivity can occur without hyperglycemia.
• 18:51
  SPEAKER_00: Optic nerve head astrocytes exposed to oxidative products show glutathione depletion, NRF2 activation, inflammatory signaling, and mitochondrial stress.
• 19:01
  SPEAKER_00: Therefore, glucose is not required for this disease pathway.
• 19:05
  SPEAKER_00: It may instead act as an additional metabolic stressor that makes the optic nerve more vulnerable.
• 19:11
  SPEAKER_00: Dose response patterns.
• 19:12
  SPEAKER_00: Why the effect is not always linear.
• 19:15
  SPEAKER_00: The experimental evidence suggests a general pattern, but not a simple straight-line dose response.
• 19:21
  SPEAKER_00: For the full table, please open this article on VisualFieldTest.com.
• 19:26
  SPEAKER_00: Several findings illustrate this progression.
• 19:28
  SPEAKER_00: In primary rat miller cells exposed to 25 millimoles per liter glucose, reactive oxygen species increased, but cell death was not detected over 48 hours.
• 19:38
  SPEAKER_00: The cells showed a delayed antioxidant response.
• 19:42
  SPEAKER_00: In a rat miller cell line exposed to 30 millimoles per liter glucose for seven days, mitochondrial fragmentation, respiratory impairment, cytochrome C release, and apoptosis were observed.
• 19:54
  SPEAKER_00: In retinal ganglion cell cultures tested at 5.5, 25, 50, and 100 millimoles per liter glucose, cell proliferation declined as glucose concentration increased, with the greatest suppression at 100 millimoles per liter.
• 20:09
  SPEAKER_00: A retinal neurovascular model used 5.5, 25, 50, 100, and 150 millimoles per liter glucose together with matched manitol controls.
• 20:20
  SPEAKER_00: Including osmotic controls is important because very high glucose can injure cells through both glucose-specific metabolic effects and nonspecific osmotic stress.
• 20:30
  SPEAKER_00: Retinal astrocytes exposed to approximately 40.7 millimoles per liter glucose became inflammatory and functionally abnormal, but did not show prominent apoptosis, apparently retaining a strong NRF-2 response.
• 20:44
  SPEAKER_00: These differences show that cell type and exposure duration may matter as much as glucose concentration.
• 20:50
  SPEAKER_00: A concentration that produces adaptation in retinal astrocytes may produce mitochondrial failure in a Muller cell line or retinal ganglion cell model.
• 20:59
  SPEAKER_00: Overall assessment of the evidence.
• 21:02
  SPEAKER_00: The evidence is strongest for the following conclusions.
• 21:05
  SPEAKER_00: High glucose increases oxidative stress in multiple ocular cell types.
• 21:10
  SPEAKER_00: Mitochondrial structure and function are altered in Muller cells and retinal ganglion cell models.
• 21:15
  SPEAKER_00: Mitochondrial injury can activate the cytochrome C and caspase pathway of apoptosis.
• 21:21
  SPEAKER_00: NRF2 is a major protective pathway, and experimentally increasing NRF2 activity can protect retinal ganglion cells.
• 21:29
  SPEAKER_00: The NRF2 response is not uniformly suppressed.
• 21:32
  SPEAKER_00: It may be transiently impaired, delayed, or inadequate in some cells while remaining strongly inducible in others.
• 21:39
  SPEAKER_00: Retinal astrocytes can become reactive and inflammatory without immediately dying.
• 21:44
  SPEAKER_00: Direct evidence connecting high glucose specifically to optic nerve head astrocyte reactivity is still less complete than evidence from retinal Miller cells, retinal astrocytes, and non-diabetic oxidative stress models.
• 21:58
  SPEAKER_00: Diabetes likely magnifies these pathways by adding vascular, inflammatory, lipid, and mechanical stresses.
• 22:05
  SPEAKER_00: Conclusion.
• 22:06
  SPEAKER_00: High sugar exposure can affect the retina through a connected network of oxidative stress, mitochondrial dysfunction, impaired antioxidant adaptation, glial reactivity, and neuronal apoptosis.
• 22:18
  SPEAKER_00: For retinal ganglion cells, the most concerning sequence is reactive oxygen species accumulation, followed by mitochondrial membrane and respiratory abnormalities, cytochrome C release, caspase activation, and apoptosis.
• 22:30
  SPEAKER_00: NRF-2 provides an important defense, but high glucose may produce a response that is too weak, too delayed, or too short-lived to restore glutathione and mitochondrial function.
• 22:42
  SPEAKER_00: Retinal Miller cells and retinal astrocytes show different levels of resilience.
• 22:46
  SPEAKER_00: Some maintain NRF-2 activation and survive while becoming inflammatory or metabolically dysfunctional.
• 22:53
  SPEAKER_00: Optic nerve head astrocytes also possess strong antioxidant defenses, but oxidative stress can deplete glutathione, alter mitochondrial function, and promote a reactive phenotype.
• 23:05
  SPEAKER_00: In diabetes, these redox changes may combine with vascular and pressure-related stresses, increasing the likelihood of retinal ganglion cell and optic nerve injury.
• 23:15
  SPEAKER_00: The best supported interpretation is not that every high glucose exposure immediately causes neuronal death.
• 23:21
  SPEAKER_00: Rather, persistent or repeated hyperglycemic stress may gradually reduce the metabolic and antioxidant reserve of the retina and optic nerve, making retinal ganglion cells less able to tolerate additional injury.
• 23:35
  SPEAKER_00: All links to sources are available in the text version of this article.
• 23:39
  SPEAKER_00: You can find the full article at VisualFieldTest.com.
• 23:43
  SPEAKER_00: Thanks for listening.
• 23:45
  SPEAKER_00: To check your visual field, click the link at the bottom of this article or visit VisualFieldtest.com.