Disease-modifying glaucoma drugs

Is Glaucoma an Energy Failure Disease? Mitochondria, Aging, and the Optic Nerve

This audio article is from VisualFieldTest.com [https://visualfieldtest.com]. Read the full article here: https://visualfieldtest.com/en/is-glaucoma-an-energy-failure-disease-mitochondria-aging-and-the-optic-nerve [https://visualfieldtest.com/en/is-glaucoma-an-energy-failure-disease-mitochondria-aging-and-the-optic-nerve] Test your visual field online: https://visualfieldtest.com [https://visualfieldtest.com] Support the show so new episodes keep coming: https://www.buzzsprout.com/2563091/support [https://www.buzzsprout.com/2563091/support] Excerpt: Introduction Glaucoma is a leading cause of irreversible blindness worldwide, affecting tens of millions of people (). It is traditionally linked to high eye pressure (intraocular pressure), but many patients continue to lose vision even when pressure is controlled. Scientists now think that pressure is only part of the story. Inside each retinal ganglion cell (RGC) – the neurons whose long fibers form the optic nerve – a complex energy crisis may arise over years. In this scenario, glaucoma becomes an “energy failure” disease: if an RGC cannot make enough energy, its axons and connections slowly fail, damaging vision. This article explores why optic nerve cells need so much energy, how aging and stress may starve them, and what researchers are trying – often by boosting cell power – to save the nerve. We’ll also connect these ideas to other brain diseases and early experimental treatments that aim to shore up cellular energy. Why Retinal Ganglion Cells Need Huge Energy Retinal ganglion cells are the nerve cells in the eye that send visual signals from the retina to the brain. They have an especially high energy demand. Unlike most neurons, RGC axons (the nerve fibers) travel a long distance without the usual insulating sheath called myelin. In fact, all along the length of the retina and optic nerve head, RGC axons are unmyelinated (). Each electrical signal (“action potential”) must be actively regenerated step by step, which uses a lot of energy. To meet this demand, RGCs pack in mitochondria – the cell’s “power plants” – along their axons, especially at the optic nerve head where the fibers take a sharp turn out of the eye (). The region just inside the optic nerve is mechanically stressful (squeezed by eye pressure and movement), so RGCs concentrate mitochondria there to keep energy up under strain. In short, RGCs are among the most energy-hungry cells: they “never stop,” and their unique structure means they are built with dense fuel-supplies () (). In practice, this means any problem that reduces their fuel can quickly hurt RGCs. Neurons rely on two main pathways to turn nutrients into ATP (cellular energy): glycolysis (using sugar) and oxidative phosphorylation (using oxygen in mitochondria) (). RGCs ride a delicate balance between these, and they depend on continuous delivery of oxygen and nutrients through tiny blood vessels. Even slight disruptions – like slower blood flow or extra pressure – can tip the balance. Glaucoma Stressors: Pressure, Blood Flow, and Aging Glaucoma stresses RGCs in several ways, any of which can hurt mitochondria (and thus energy supply). Eye Pressure and Blood Flow Elevated eye pressure makes it physically harder for blood to reach the retina and optic nerve. Imagine pinching a hose: reduced blood (and oxygen) supply starves cells of fuel. In glaucoma, this can create brief “ischemia-reperfusion” injury – a kind of mini-stroke where blood flow drops and then suddenly returns. During this process, mitochondria produce extra reactive oxygen species (ROS) that act like toxic sparks inside cells (). Indeed, animal studies show that high pressure causes a surge of oxidative stress in the retina. For example, when researchers raised eye pressure in rats, levels of glutathione (the cell’s natural antioxidant) plummeted while markers of superoxide (a damaging oxygen molecule) rose in the retinal ganglion cell layer (). In other words, high pressure literally starves RGCs and floods them with damaging free radicals () (). Over time, this “chemical stress” weakens RGC mitochondria, making them less able to make energy. Aging and NAD Decline Age is the other big risk factor. As we grow older, all our cells lose some ability to fight stress. In RGCs, a key change is a drop in NAD (nicotinamide adenine dinucleotide) – a molecule that cells use like currency in energy production. Multiple studies in glaucoma models report that retinal NAD levels fall with age (and with pressure) () (). This makes a perfect storm: older RGCs have less raw fuel (NAD) to run their mitochondria, so they are already close to energy failure. The consequences are clear in experiments. In a mouse study, the researchers found that boosting NAD by giving nicotinamide (a form of vitamin B3) protected RGCs starkly. At the highest dose, 93% of treated eyes had no glaucoma damage at all, even though eye pressure still rose (). This shows that simply “refilling the battery” can nip the damage in the bud. In other work, aging mice given high-dose nicotinamide kept their NAD levels high long-term and resisted vision loss (). Conversely, human glaucoma patients have been found to have lower blood levels of vitamin B3 compared to people without glaucoma (). All together, the evidence suggests that age-related NAD loss tips some RGCs into an energy crisis () (). Oxidative Stress: When Cells Burn Too Much Oxidative stress is a term you will hear often in glaucoma studies. It simply means the balance between harmful oxygen molecules (like free radicals) and the cell’s antioxidants is tipped so far that damage occurs. Mitochondria naturally leak some reactive oxygen during energy production, and small amounts are normal. But when pressure, poor blood flow, or aging disrupts the system, RGCs generate excess radicals faster than they can clean them up. One review explains: reactive oxygen are “essential participants” in cell signaling, but when production overwhelms the antioxidant capacity, damage to cellular molecules ensues – a state of oxidative stress (). In glaucoma, oxidative stress is seen in multiple ways. Studies have found oxidative modifications of proteins in dying RGCs, and loss of antioxidants in the eye’s fluids () (). In experimental models, artificially raising eye pressure causes spikes of oxidative markers in the retina () (). Oxidative stress itself can damage mitochondria and other cell parts. Proteins, DNA, and membrane fats get “shot” by these reactive species, making mitochondria less efficient and cells more prone to self-destruct. This is why antioxidants are considered for therapy (see below): by bolstering the cell’s cleanup crew, we hope to prevent the energy machinery from self-immolating. Mitochondrial Dysfunction and Optic Nerve Damage When mitochondria start failing, an RGC can’t make enough ATP, its essential energy packets. The results are profound: the nerve fiber (axon) can no longer transport cellular cargo (like proteins and organelles) up and down its long length. Researchers describe this as a breakdown of axonal transport – think of it like cargo trucks stuck on a road because there’s no fuel. In glaucoma models, impaired axonal transport is one of the earliest signs of trouble (). This eventually leads to thinning of the optic nerve and failure of synapses in the brain – and the visual field loss patients see. Microscopic examinations confirm that mitochondria look abnormal long before RGCs die. For example, in one glaucoma model, the tiny folds inside mitochondria (“cristae”) become reduced on electron microscopy, signaling collapse of energy factories even before any cell loss (). The cells also lose internal structure: in DBA/2J mice (a glaucoma strain), RGCs start retracting branches and pruning connections once energy falters (). Bursting these processes of energy shortfall and structural damage is a vicious cycle: more oxidative stress impairs mitochondrial function, and bad mitochondria create more oxidative stress, along with activating cell death programs () (). Thus, by the time clinical signs appear, the RGCs have already lost much of their support. This energy-starvation model helps explain why some glaucoma patients (especially the elderly) continue to worsen even with normal eye pressure – their cells simply can’t keep up. Neuroinflammation and the Eye’s Immune Storm Another layer is neuroinflammation. The optic nerve is supported by glial cells (like astrocytes and microglia) that normally help neurons. But when RGCs struggle, they send distress signals that activate these glial cells. At the same time, damaged mitochondria themselves release inflammatory cues. For instance, fragments of mitochondrial DNA can act as “danger signals” that trigger the cell’s immune sensors (e.g. the NLRP3 inflammasome), causing release of inflammatory cytokines like IL-1β (). Once inflammation kicks in, it further robs cells of energy (it takes fuel for immune reactions) and can directly damage neurons. In fact, a recent review noted that in glaucoma, “crosstalk” between mitochondria and inflammation accelerates damage: injured mitochondria amp up immune signals and, in turn, immune signals further drown the cell’s power production (). Practically, this means that high pressure or oxidative stress in the optic nerve can lead to an immune reaction similar to what we see in Alzheimer’s or Parkinson’s disease, contributing to a downward spiral in RGC health () (). While our technology is still catching up in mapping inflammation in the eye, it’s clear that metabolic failure and immune activation go hand in hand. Imaging of human glaucomatous optic nerves shows markers of inflammation, and many immune-related genes are switched on in stressed optic nerve tissue. Th Support the show [https://www.buzzsprout.com/2563091/support]

The Future of Glaucoma Care May Be Personal: Matching Treatment to Each Patient’s Risk

This audio article is from VisualFieldTest.com [https://visualfieldtest.com]. Read the full article here: https://visualfieldtest.com/en/the-future-of-glaucoma-care-may-be-personal-matching-treatment-to-each-patient-s-risk [https://visualfieldtest.com/en/the-future-of-glaucoma-care-may-be-personal-matching-treatment-to-each-patient-s-risk] Test your visual field online: https://visualfieldtest.com [https://visualfieldtest.com] Support the show so new episodes keep coming: https://www.buzzsprout.com/2563091/support [https://www.buzzsprout.com/2563091/support] Excerpt: The Future of Glaucoma Care May Be Personal: Matching Treatment to Each Patient’s Risk Glaucoma is a chronic optic nerve disease and a leading cause of irreversible blindness. Traditionally, doctors have focused on one main factor – eye pressure – to diagnose and treat glaucoma. But in recent years experts have realized that glaucoma behaves very differently from person to person. In fact, two patients with the same eye pressure can have very different outcomes. For example, one patient might slowly lose vision despite moderate pressure, while another with high pressure stays stable for years. This is because many hidden factors – genetic traits, eye anatomy, blood flow, lifestyle habits and more – all influence glaucoma risk () (). Today we are on the brink of truly personalized glaucoma care, where doctors will tailor follow-up plans and treatments to each person’s unique risk profile. In this article we’ll explore how clinicians estimate glaucoma risk now, and how future tools like advanced imaging, genetics and artificial intelligence (AI) may change things. We’ll give examples of different patient profiles and imagine what glaucoma care might look like in 2030. We’ll also consider possible pitfalls, like too many tests or unequal access to new technology. Why Two Patients with the Same Pressure Can Have Different Outcomes A key reason is that glaucoma is multifactorial. High eye pressure (intraocular pressure, IOP) is the best-known risk factor, but it is far from the only one. Some people’s optic nerves are simply more vulnerable than others’. For example, one large study (the Ocular Hypertension Treatment Study) found that people who went on to develop glaucoma tended to be older, already have larger “cup-to-disc” ratios in their optic nerve, and have thinner corneas than those who did not (). In other words, an older person with a fragile optic nerve and a very thin cornea might suffer damage at a given pressure level that a younger person with a robust nerve might tolerate. Similarly, about half of glaucoma patients never have very high pressure – so-called normal-tension glaucoma – but still lose vision because of other problems like poor blood flow or genetic factors (). The European Glaucoma Society even emphasizes that “IOP is not the only factor” in glaucoma risk (). To put it another way: imagine two people, both with an eye pressure of 25 mmHg. Patient A has a thin cornea (which actually masks higher true pressure) and a family history of glaucoma. Patient B has a thick cornea and no family history. Patient A’s optic nerve may already be stressed from years of even slightly elevated pressure and blood flow issues, so glaucoma damage can progress more quickly. Patient B’s healthier eyes and strong corneas might tolerate that pressure without harm for much longer. In short, each eye is different – like a unique machine with its own weak points – so identical pressures don’t guarantee identical outcomes () (). How Doctors Estimate Glaucoma Progression Risk Today Currently, eye doctors (ophthalmologists) piece together many clues to judge each patient’s risk of vision loss. There’s no single “glaucoma paint-by-numbers” formula used for everyone, but clinicians pay attention to known risk factors and test results. Some key elements include: Baseline eye pressure (IOP): Even if pressure isn’t the whole story, higher IOP generally raises glaucoma risk. Yet doctors also consider pressure fluctuations over time, not just one reading (). Optic nerve appearance: A large or asymmetric cup-to-disc ratio (the hollow in the optic nerve head) suggests more damage or susceptibility (). If one eye’s nerve shows more cupping, that eye may need stricter control. Visual field tests: A standard visual field test maps what areas a person can see. Early loss in these tests indicates glaucoma onset. Doctors look at field results over time – a faster rate of field loss means higher risk. Retinal imaging (OCT): Technologies like Optical Coherence Tomography (OCT) give high-resolution scans of the optic nerve and its retinal nerve fiber layer. Thin or thinning fiber layers can signal higher progression risk even before fields are affected. Corneal thickness (pachymetry): The central cornea’s thickness is measured because it affects pressure readings. A thin cornea not only underestimates true IOP, it also independently correlates with nerve vulnerability (). In fact, the Ocular Hypertension Study found people with corneas ≤555 µm had three times the risk of glaucoma compared to those with thicker corneas (). Age: Older patients generally have higher risk. Each additional decade of age slightly increases the odds of progression. Myopia (nearsightedness): Being very nearsighted stretches the eye and optic nerve, raising glaucoma risk (). Family history: A strong clue – a first-degree relative (parent, sibling) with glaucoma boosts risk dramatically. One review found relatives of glaucoma patients had a 22% lifetime risk, versus only about 2–3% for relatives of people without glaucoma (). Race/ethnicity: People of African descent have higher rates of open-angle glaucoma, and those of Asian descent have more angle-closure forms (). Certain genetic backgrounds color risks. Systemic health: Conditions like diabetes and high or low blood pressure [L557–560] can worsen optic nerve health. For instance, very low blood pressure at night (“nocturnal hypotension”) or sleep apnea may starve the eye of blood, adding risk () (). Lifestyle factors: Smoking, for example, damages tiny blood vessels and is linked to glaucoma progression (). Migraine and systemic vasospastic issues can also hint at vulnerable optic nerve perfusion (). Medication adherence: Known modifiable factor – if a patient doesn’t stick to treatments, risk climbs. Often, doctors will use risk calculators or scoring systems. For example, the Ocular Hypertension Treatment Study (OHTS) provided a calculator for patients with high pressure but no glaucoma. It combines age, pressure, corneal thickness, optic disc measurements and more to estimate a 5-year glaucoma risk () (). Such tools quantify how multiple factors interplay. In practice, doctors integrate all these clues. If most signs point to low risk (thick corneas, no family history, only slight optic changes), a patient might only need mild treatment or routine monitoring. But high-risk patients – say, an older person with very cupped optic nerves and thin corneas – would likely get aggressive treatment to lower pressure promptly () (). The Role of Key Tests: OCT, Visual Fields, Pachymetry and More Two tests are especially important today: Visual Field Testing: This functional test charts a person’s field of vision (often using a computerized device). It detects visual field loss from glaucoma – for example, small scotomas (blind spots) that develop in peripheral vision. Tracking changes in the field over months or years lets doctors calculate how fast vision is worsening. Faster loss means a higher risk profile and need for stronger therapy. Optical Coherence Tomography (OCT): This is an imaging “CAT scan” of the eye. OCT gives a high-resolution cross-section of the retina and optic nerve. It measures the thickness of retinal nerve fibers and shows structural damage. Thinning on OCT often precedes visible field loss. By comparing OCT images over time, doctors spot subtle nerve fiber decline. This helps them catch progression earlier and tailor treatment. (Emerging OCT angiography can even image blood flow around the optic nerve.) Other measurements round out the picture: Pachymetry for corneal thickness, as noted. Gonioscopy to check the iris and angle (to rule out angle-closure threat). Photography of the optic nerve to record appearance. Intraocular Pressure Checks (often at different times of day or after posture changes). Together, these tests help classify each patient. One might say: “Our patient has moderately damaged fields and moderately thin nerve fiber layers, with IOP usually in the mid-20s. Given her thin corneas and a family history of glaucoma, her risk is above average.” Another patient with similar pressures but normal OCT and no family risk might be classified as lower risk. AI for Tailoring Follow-Up and Treatment Artificial Intelligence (AI) is starting to enter glaucoma care, promising to personalize decisions further. Advanced AI systems can analyze large amounts of data – images, test histories, even genetics – to spot patterns a human might miss. For example, a recent review of over 150 studies found that deep-learning AI on fundus photos or OCT scans can match or even exceed specialist accuracy for glaucoma detection (). More impressively, some sequence-based AI models could detect subtle worsening of visual fields up to 1.7 years earlier than traditional trend analysis (). In other words, an AI algorithm looking at a series of fields and OCTs could warn a doctor long before visual acuity worsens visibly. Other AI models have been trained to predict which patients are likely to need surgery – one multi-modal network combining OCT, field tests and clinical data achieved an accuracy (ROC AUC ~0.92) in forecasting eventual need for incisional surgery (). Support the show [https://www.buzzsprout.com/2563091/support]

Can the Optic Nerve Be Protected? The New Neuroprotection Era in Glaucoma Research

This audio article is from VisualFieldTest.com [https://visualfieldtest.com]. Read the full article here: https://visualfieldtest.com/en/can-the-optic-nerve-be-protected-the-new-neuroprotection-era-in-glaucoma-research [https://visualfieldtest.com/en/can-the-optic-nerve-be-protected-the-new-neuroprotection-era-in-glaucoma-research] Test your visual field online: https://visualfieldtest.com [https://visualfieldtest.com] Support the show so new episodes keep coming: https://www.buzzsprout.com/2563091/support [https://www.buzzsprout.com/2563091/support] Excerpt: Can the Optic Nerve Be Protected? The New Neuroprotection Era in Glaucoma Research Glaucoma has long been called the “silent thief of sight” – historically treated by focusing on intraocular pressure (the fluid pressure in the eye). But a growing body of research shows that glaucoma is not just a plumbing problem. It is also a neurodegenerative disease that gradually destroys the eye’s nerve cells. Imagine your eye as a camera and the optic nerve as the cable that carries its images to your brain. In glaucoma, this cable gets frayed and rusty over time, not only from high pressure but from an internal “wear-and-tear” process. In this article, we’ll explain why that matters, and how new treatments are trying to protect the neural wiring of the eye. We’ll use simple metaphors – nothing too technical – so you can follow along easily. Retinal Ganglion Cells: The Eye’s Messengers Inside the eye’s retina, special nerve cells called retinal ganglion cells (RGCs) work like telephone wires, carrying visual signals from the eye to the brain. Each eye has about 1.5 million of these cells, whose long fibers bundle together into the optic nerve (). Think of RGCs like millions of tiny light bulbs along a cable: when light hits the retina, RGCs convert that information into electrical signals that zoom up the optic nerve to the brain. RGCs are crucial. Once they die, our vision is lost in those areas – they do not regenerate on their own. As one review bluntly puts it, glaucoma is marked by the “irreversible loss of retinal ganglion cells (RGCs)” (). In other words, if these cells “burn out,” the damage is permanent. A 2021 study of lab-transplanted RGCs emphasizes that because RGCs “transmit visual information from the retina to the brain, their progressive loss results in fading vision and, ultimately, blindness” (). In everyday terms, losing RGCs is like cutting fibers in a cable – the signal can’t get through, and you get a blind spot or fair-sized dark area in your vision. Because RGCs do so much work, they burn a lot of energy. They’re packed with tiny power plants called mitochondria, and they need good blood flow and nutrients. This makes them shinny glass in a storm: delicate and easily damaged. In glaucoma, anything that weakens RGCs – from starvation of blood to chemical “rust” – can cause them to die. Glaucoma: More Than Just High Eye Pressure Traditionally, doctors have measured eye pressure as the key glaucoma risk. High pressure can physically squeeze the optic nerve fibers as they exit the eye (like pressing on a cable at the wall). This pressure can block roads for nutrients, slow down the traffic of essential chemicals, and trigger cell damage (). But scientists now understand that high pressure is only one piece of the puzzle. In many patients, something else is at work hurting those nerve cells, even when pressure is normal. Neurodegeneration and the Brain In fact, glaucoma is increasingly seen as similar to other nerve diseases like Alzheimer’s or Parkinson’s, but focused on the eye and its brain connection. Studies have found that damaging glaucoma can spread beyond the eye all the way into the brain’s visual centers (). For example, a recent review explains that people with glaucoma often show changes in their brain, such as thinning of visual cortex or altered neural connections – much like early Alzheimer's patients (). This hints that glaucoma triggers a kind of “domino effect” of damage along the visual pathways, not unlike what happens with other neurodegenerative diseases. Mechanistically, researchers are finding shared culprits between glaucoma and brain diseases: things like broken mitochondria, chronic inflammation, and clogged nerve transport systems (). In simple terms, if Alzheimer’s is a problem of aging brain cells, glaucoma may be a related problem of aging eye cells (RGCs) and their brain links. Beyond Pressure: Inflammation, Oxidative Stress, and Vascular Factors Because glaucoma is more than just “too much fluid,” other harmful processes are blamed when we see vision worsen despite good pressure control. One key factor is inflammation. The eye – like the brain – has immune-support cells (glia) that can overreact when stressed. Stressed RGCs send out danger signals such as reactive oxygen species (free radicals), nitric oxide, and inflammatory proteins (like TNF-α and interleukins) (). This can trigger chronic inflammation that ironically damages the very neurons it was meant to protect. Here’s an analogy: imagine RGCs as factories. When something goes wrong (like machinery overheating), the factory alarms (inflammatory signals) go off. If the alarm system is too sensitive or stuck on, it can end up hurting the factory itself, not helping it. In glaucoma, exhausted RGC mitochondria may flood the retina with reactive oxygen (oxidative stress) that activates this “alarm,” causing friendly fire against nerves (). One review on glaucoma neuroinflammation describes how broken mitochondria in RGCs can set off the immune system, leading to a sustained damaging response (). In short: when RGC energy centers fail, they trigger a damaging inflammation loop within the eye. Vascular factors also play a role. The tiny blood vessels that feed the optic nerve can be sensitive. Eyedrops that raise heart rate or conditions like diabetes and high blood pressure can affect blood flow to the eye. Low blood pressure (especially at night) or vascular “spasms” are linked to worse glaucoma because they temporarily starve RGCs of oxygen (). For instance, one comprehensive review notes that reduced blood perfusion pressure and faulty blood vessel regulation likely help drive RGC damage (). In our cable analogy, this is like having power fluctuations in the electrical grid; even if the cable and camera are fine, if the power supply is shaky, the system falters. This is why glaucoma specialists often pay attention to cardiovascular health and sometimes even advice moderating certain blood pressure medications at night. Why Pressure Control Isn’t Always Enough All these factors explain why some patients keep losing vision even when their eye pressure is low or normal. For example, “normal-tension glaucoma” is a common scenario where eye pressure never gets high, yet RGC damage and optic nerve cupping progress (). Conversely, in some patients with high pressure, lowering it stops further damage. But in many others, damage creeps on. As one expert noted, despite “apparently good” pressure readings, disease can worsen in a number of patients (). In other words, lowering pressure is necessary but sometimes not sufficient. A meta-analysis of patient studies put it starkly: doctors have observed that RGC loss often “continues despite lowering IOP,” meaning that treatments only focused on pressure “may not be beneficial for some glaucoma patients” (). Think of blood pressure for analogy: lowering blood pressure helps most high-risk people, but if someone is still leaking cholesterol plaques or has other heart risks, they may still have a heart problem despite normal pressure. Similarly, in glaucoma we must also target the nerve itself, not just the fluid pressure. The Search for Neuroprotective Treatments Since RGCs are dying by many causes, scientists have searched for neuroprotective strategies: treatments that can keep these nerve cells alive longer or healthier. In simple terms, neuroprotection means anything aimed at preventing nerve damage or death (). This new era of research looks beyond pressure: it asks, “How can we shield the optic nerve from harm, regardless of the pressure?” Researchers are exploring many avenues, from drugs to diet to bioengineering. Here are some current and emerging strategies being studied: Neuroprotective Eye Medications: Some existing glaucoma drugs might have nerve-saving effects. For example, brimonidine (an eye drop that lowers pressure) was hoped to strengthen RGC survival. Lab studies in animals showed promise, but human trials have so far been disappointing (). An evidence review reports that to date, clinical trials of such “neuroprotectors” have failed to show clear benefits in people (). Another drug, memantine (used in Alzheimer’s), was tested in large glaucoma trials but did not prove effective. At present, manufacturers have not reported any significant vision benefit, so memantine is not part of glaucoma care. In short, while drugs like these are studied, none are yet a proven neuroprotective cure. Growth Factors and Gene Therapy: Scientists have tried giving eyes extra “growth factors” – proteins that help nerves survive and grow. For example, nerve growth factor (NGF) or brain-derived neurotrophic factor (BDNF) can keep RGCs from dying in animals. Experiments involving viral gene therapy are in early stages: for instance, researchers can inject a harmless virus carrying genes for protective proteins into the eye. One phase-1 trial (GVB-2001) is even testing a gene treatment to relax eye muscles for pressure control (), and similar approaches might deliver neuroprotective genes later on. These techniques are still experimental. The hope is to one day use gene vectors to make the eye produce its own protective agents, but it is de Support the show [https://www.buzzsprout.com/2563091/support]

Sustained-release glaucoma implants

This audio article is from VisualFieldTest.com [https://visualfieldtest.com]. Read the full article here: https://visualfieldtest.com/en/sustained-release-glaucoma-implants [https://visualfieldtest.com/en/sustained-release-glaucoma-implants] Test your visual field online: https://visualfieldtest.com [https://visualfieldtest.com] Support the show so new episodes keep coming: https://www.buzzsprout.com/2563091/support [https://www.buzzsprout.com/2563091/support] Excerpt: Sustained-Release Glaucoma Implants Imagine having glaucoma and relying on daily eye drops to protect your vision – but every night, whether out of fatigue or busy schedule, you forget or skip them. Many patients know this drill: missing eye-drop doses, administering them poorly, or giving up because the drops sting or irritate. Glaucoma often feels like a hidden disease – vision can worsen silently when pressure stays high – so skipping medication can be dangerous. Studies show that roughly one in three glaucoma patients admit they do not use their eye drops consistently (). Side effects like burning, redness or dry eyes make matters worse: patients who experience side effects are much more likely to stop or skip treatments (). In short, relying on daily eye drops is a major problem – many people simply do not take them as prescribed, meaning real-world glaucoma control suffers () (). Ophthalmologists and researchers have long noted these challenges. Topical drops can work well if used perfectly, but in reality poor adherence and side effects are common (). Recognizing this, scientists have developed sustained-release alternatives. The idea is to deliver glaucoma medicine inside or near the eye once, so it slowly bathes the eye with medication for months – eliminating the need for a patient to remember daily drops. These new approaches include small intracameral implants (placed inside the eye), drug-eluting devices (like medicated spacers or rings), and long-acting prostaglandin delivery systems. By continuously releasing medication over time, these technologies promise steadier eye pressure control and far fewer missed doses, potentially reshaping glaucoma care () (). Why Eye Drops Are So Hard Glaucoma treatment often starts with eye-drop medications that lower intraocular pressure (IOP). But using drops correctly isn't easy. Many patients struggle with arm or neck stiffness, shaky hands, or poor vision that makes self-instilling drops difficult. People sometimes miss the eye entirely, or blink the drop out. Even simply remembering to take an oftentimes twice-daily dose can be a challenge amid busy lives. Surveys and studies confirm this: a review found that 30–50% of patients with chronic diseases in general do not adhere perfectly to their treatments (), and in glaucoma specifically roughly 30% admit missing enough drops to be considered “non-adherent” () (). Side effects add another hurdle. Glaucoma drops often contain preservatives or strong active drugs, which can cause stinging, redness, or eye dryness. For example, one study noted that about 38% of patients who had any side effects at all admitted poor use, compared to only 18% of those without side effects (). Preservatives in drops (like benzalkonium chloride) can irritate sensitive eyes, worsening comfort. Over time, patients may decide that putting drops in each day is “too unpleasant,” leading them to skip doses or stop the medication entirely. All this adds up to a hidden but serious real-world problem. In the controlled setting of a clinical trial, patients may dutifully use every drop and achieve excellent IOP control, but in everyday life “the patient-independent” issues – forgetfulness, dexterity, discomfort – often mean glaucoma is undertreated. Doctors ring alarm bells: poor adherence is a leading cause of glaucoma progression and vision loss. As one glaucoma review put it, conventional drops suffer from “poor patient adherence” and “local side effects”, which spurs the search for better delivery systems (). How Sustained-Release Systems Work Sustained-release glaucoma devices are built to solve these adherence issues. Instead of relying on a patient to administer a drug every day, the medication is encapsulated inside an implant or insert. These can be placed in or around the eye in a simple procedure, and then they continuously leach small doses of medicine over weeks to months. Intracameral implants: These are tiny drug-packed rods or reservoirs placed in the anterior chamber (front part) of the eye. For example, a biodegradable polymer rod can be injected through a needle into the eye; once inside, the polymer slowly breaks down, releasing the drug inside the eye over time (). Some devices, like the newly FDA-approved iDose® TR, use a tiny titanium reservoir anchored in the eye’s drainage angle, dispensing travoprost around the clock () (). Drug-eluting inserts or depots: Other ideas include punctal plugs or ocular rings: think of a soft plug placed in the tear duct or a ring in the eyelid that slowly releases prostaglandin analogs. These sit in the eye’s drainage or surface and diffuse medication gradually. Some specialty contact lenses have been tested that soak up a prostaglandin and sit on the eye, giving off drug slowly over days. Biodegradable implants: Many approaches use biopolymers (like PLGA or PEA) that safely dissolve in the eye. For instance, the Travoprost XR (ENV515) implant is made of a biodegradable material designed to release travoprost evenly for 6–12 months (). After that period, it has fully dissolved, and if needed a new one can be injected. Other implants may need manual removal or replacement. The common theme is “set it and forget it.” A doctor or specialist places the device in the eye during a visit. The patient then goes home and in the background (literally behind their eyeball) the medication is continuously supplied, day and night, without any effort from the patient. It’s like having a mini medication pump inside the eye. Researchers often describe this as “continuous drug delivery” – a stark contrast to the ups and downs of dosing with drops (). Example: Bimatoprost Sustained-Release (Durysta) One real-world example is Durysta® (bimatoprost SR) – the first FDA-approved implant (March 2020) for glaucoma treatment (). This tiny cylindrical implant contains 10 micrograms of bimatoprost (a prostaglandin analog) embedded in a solid polymer. It is injected with a fine needle into the front of the eye in a quick office procedure. Once inside, the polymer slowly dissolves, sending steady bimatoprost to the eye tissues over about 4–6 months. In clinical trials, Durysta’s single injection lowered eye pressure about as well as a daily bimatoprost drop would have, but for many patients it lasted significantly longer. Because it is biodegradable, no device removal is needed – it simply disappears over time. After one Durysta implant, many patients achieve target IOP for 6 months or more without any drops. However, the FDA label notes a key precaution: Durysta is currently approved for only one injection per eye, due to some concerns about corneal safety if repeated (). (In a few trial patients, multiple Durysta implants led to too much stress on the cornea’s cells, so repeated use is not allowed at present.) Example: Travoprost Implant (iDose® TR and Others) Travoprost, a common eye-drop medication, is also being delivered by implants. The new iDose® TR (by Glaukos) received FDA approval in December 2023 (). This device is a tiny, non-degradable pill made of titanium with 75 micrograms of travoprost inside. A surgeon places it in the drainage angle of the eye, and a thin membrane slowly releases travoprost 24/7 for about three years () (). Once that time’s up, the implant can be removed or replaced. In pivotal trials, a single iDose implant lowered pressure effectively for years, matching the effect of daily travoprost drops. Most people in the trials were able to reduce or stop additional glaucoma drops after the implantation. Another travoprost implant under study is Travoprost XR (ENV515) – a biodegradable rod similar in concept to Durysta but with travoprost. Preclinical tests in dogs and early human trials show that a single ENV515 injection lowers eye pressure significantly for many months (). In one trial, by Day 25 the implanted eye had a 30%+ drop in IOP, comparable to someone using daily travoprost eye drops (). Later in that study, most patients on the implant achieved target pressure control for a year or more. ENV515 is still going through clinical testing and awaits FDA approval (). Other Investigational Systems Research is ongoing on many other sustained-release systems. For instance, researchers have tested medicated contact lenses that slowly release latanoprost for a week, and punctal plugs that release travoprost or latanoprost. Some labs are developing long-acting injections (like microscopic particles) placed under the conjunctiva that dissolve over time. These are not yet in mainstream use, but they illustrate the wide interest in “drop alternatives.” Benefits of Sustained-Release Implants These new technologies offer several clear advantages over daily drops: Steady IOP control: Instead of daily peaks and troughs from each drop, the eye is bathed in a constant low-dose stream of medication. This can keep pressure very stable. Some trials have found that implant patients have more consistent IOPs and less fluctuation than those on drops. No missed doses: Because the patient doesn’t have to apply a drop, there’s virtually no chance of forgetting or misusing the medication. In a large travoprost implant trial, about 80–84% of patients using an implant reduced or elimin Support the show [https://www.buzzsprout.com/2563091/support]

Disease-modifying glaucoma drugs

This audio article is from VisualFieldTest.com [https://visualfieldtest.com]. Read the full article here: https://visualfieldtest.com/en/disease-modifying-glaucoma-drugs [https://visualfieldtest.com/en/disease-modifying-glaucoma-drugs] Test your visual field online: https://visualfieldtest.com [https://visualfieldtest.com] Support the show so new episodes keep coming: https://www.buzzsprout.com/2563091/support [https://www.buzzsprout.com/2563091/support] Excerpt: Introduction Glaucoma is a chronic eye disease where nerve cells in the retina and optic nerve gradually die, often causing blindness if untreated. For decades, the main proven treatment has been lowering intraocular pressure (IOP) – the fluid pressure inside the eye – to slow damage (). This is done with eye drops, laser or surgery. But pressure isn’t the whole story. Many patients still lose vision even when their pressure is well-controlled. In fact, about one-third of treated patients eventually go blind in one eye (). And some people (so-called “normal-tension” glaucoma) get damage even with normal pressure. These facts tell us that simply draining fluid is not enough. Glaucoma is fundamentally a neurodegenerative disease – nerves are dying. Scientists are now exploring whether new drugs can modify the disease itself rather than just treating pressure, by protecting the nerves and improving the eye’s blood supply. In this article, we’ll explain what “disease-modifying” means in glaucoma and why it’s exciting. We’ll look at the importance of ocular blood flow and the endothelin pathway (which can choke blood vessels), and how improving blood flow or cell health might save vision. We’ll also cover PER-001, a new drug in development by Perfuse Therapeutics (now owned by Bayer), which targets endothelin. We’ll weigh the evidence – what’s been shown so far in small trials, what’s still uncertain – and discuss what the future might hold in 3–10 years. The tone is hopeful but realistic: disease-modifying therapies could change how we treat glaucoma, but they are not cures (at least not yet). What “Disease-Modifying” Means in Glaucoma A disease-modifying therapy is one that changes the course of the disease itself, instead of just relieving symptoms. In glaucoma, that would mean a drug that actually slows or stops the nerve-cell death in the eye, not just reduces pressure. It’s a bit like how some arthritis drugs do more than just mask pain by slowing joint damage. For glaucoma, the idea is often called “neuroprotection” – protecting the retinal ganglion cells (RGCs), the neurons that carry vision signals from the eye to the brain. A classic definition says neuroprotection is treating glaucoma “by a mechanism independent of lowering IOP” (). Right now, no therapy has been proven to do this in patients. In large, decades-long studies only pressure lowering showed a clear benefit. In fact, a 2023 review in Molecular Aspects of Medicine notes that “current strategies only target intraocular pressure… and do not directly target the neurodegenerative processes” of glaucoma (). It adds that up to 40% of patients still progress to blindness in at least one eye despite strict pressure control (). So researchers say we urgently need therapies that go beyond pressure. In plain terms: imagine the optic nerve as a plant that not only needs the right water pressure but also good soil and light. Pressure drops help water travel (good!), but if the root cells are sick or starved, the plant will still die. Disease-modifying treatments aim to brighten the light or improve the soil – directly helping the cells survive and function. Blood Flow and Endothelin: Why They Matter One big area of research is improving ocular blood flow. The retina is one of the body’s hungriest tissues for oxygen and nutrients. It’s like a high-performance engine needing constant fuel. If blood flow to the retina or optic nerve is compromised, cells can suffer from ischemia (lack of oxygen). Over time, even shortfalls in blood supply can kill retinal ganglion cells. Many people with glaucoma have vascular issues: for example, some have a condition called Flammer syndrome (blood vessels that over-react) or low blood pressure at night, which can worsen eye blood flow. In normal-tension glaucoma (glaucoma at normal pressures), poor blood flow is thought to be a key culprit. Scientific studies support this. For example, an experiment showed that giving endothelin-1 (a natural chemical) to animals reduced blood flow in the retina and optic nerve, causing ischemic damage (). The same molecule, endothelin-1, also raises pressure and promotes optic nerve injury (). Endothelin is perhaps the most potent vasoconstrictor in the human body () – imagine it like a very strong clamping of blood vessels. In glaucoma patients, blood levels of endothelin-1 tend to be higher than normal. Researchers even found that blocking endothelin receptors in healthy animals had no effect on normal flow, but giving extra endothelin caused a big drop in blood flow (). In other words, endothelin ramps up only when things are already bad. Why is this important? If endothelin-1 is high in glaucoma, it could constrict the small vessels in the eye, depriving nerve cells of oxygen. A 2011 review on endothelin in glaucoma put it neatly: increased endothelin can “lead to pathological changes in the retina and optic nerve head which is assumed to contribute to the degeneration of retinal ganglion cells” (). In simpler terms, high endothelin is like turning down the road supply to the optic nerve while also turning up the pressure, double-whammying the nerve. Therefore, drugs that block endothelin (called endothelin receptor antagonists) could in theory keep vessels open and protect nerves. Is there evidence OBF (ocular blood flow) matters in patients? Measurements of blood flow in glaucoma eyes often show abnormalities, and the risk of glaucoma goes up if perfusion pressure (blood pressure minus IOP) is too low (). Clinically, some glaucoma patients benefit from treatments that improve ocular perfusion (for example, some doctors manage blood pressure or use calcium channel blockers off-label). But so far, there is no approved glaucoma drug whose main action is boosting blood flow. That’s changing in research: the idea is that if we can safely open up the eye’s blood vessels or correct vascular dysregulation, we might protect the optic nerve from ischemic damage. Mitochondria and Retinal Cell Survival Another cutting-edge concept is mitochondrial protection. Mitochondria are the “power plants” of cells, and retinal ganglion cells have extremely high energy demands. They need a lot of ATP to maintain their long axons and signaling in the retina. In glaucoma, several stresses (high pressure, free radicals, inflammation) can damage mitochondria, leading to energy failure and eventually cell death. Some genetic forms of optic neuropathy (like Leber’s hereditary optic neuropathy) show that mitochondrial DNA problems cause RGC death. In glaucoma, even without a genetic mutation, chronic stress may overload the mitochondria. Researchers are testing ways to keep mitochondria healthy in glaucoma. For instance, nicotinamide (vitamin B3), which boosts the mitochondrial energy molecule NAD+, has shown promise. In a small phase 2 trial, giving glaucoma patients a combination of nicotinamide and pyruvate (another metabolic fuel) led to a short-term improvement in visual function for many participants (). The treated patients had more visual field test points that got better (not just stopped worsening) over a couple of months compared to placebo (). Although this was a very short-term result and not yet evidence that visual loss is permanently slowed, it suggests that helping RGCs with extra fuel can improve how well they work. There are other mitochondrial and cell-targeting strategies under study. Some are antioxidants (to mop up free radicals) and others are drugs that block programs of cell death. For example, experimental treatments that pre-condition cells (using mild stress like low oxygen) can activate built-in survival genes () – this “stress response” can make RGCs temporarily more resilient. Another approach is using neurotrophic factors (like brain-derived neurotrophic factor or BDNF) or growth factors to encourage cell survival. In fact, an eye drop containing nerve growth factor (rhNGF) is now in early trials for glaucoma (), aiming to block the signal that tells RGCs to die. However, it’s important to note that most of these strategies are experimental. For instance, memantine (an Alzheimer’s drug thought to protect nerve cells by blocking glutamate toxicity) underwent large clinical trials but did not significantly slow glaucoma compared to placebo (). So, while metabolic and protective approaches are very promising in concept, proof of lasting benefit in patients is still pending. PER-001 and Other Disease-Modifying Approaches A big hope in the field right now is a drug called PER-001 (from Perfuse Therapeutics, soon to be Bayer) – an intravitreal (inside-the-eye) implant of an endothelin receptor antagonist. This is exactly the strategy of blocking endothelin discussed above. PER-001 slowly releases a small molecule that blocks endothelin receptors in the eye every six months or so (). The idea is to keep eye blood vessels open, reduce inflammation, and protect retinal cells, in addition to helping lower pressure through better outflow. What do we know about PER-001 so far? Perfuse and Bayer have released encouraging early results. In a phase 1/2a study presented in 2025, a single PER-001 injection improved visual function and retinal structure compared to control over Support the show [https://www.buzzsprout.com/2563091/support]