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These therapies may help slow or stop the progression of macular degeneration. Share on PinterestDaniel Day/Getty ImagesMacular degeneration is the leading cause of vision loss and blindness in people ages 65 years and older in the United States. This condition affects a person’s ability to see objects clearly, which significantly hinders the ability to perform daily activities such as driving, reading, and watching television. In this article, learn more about gene therapy and its potential role in treating macular degeneration. How does gene therapy work for macular degeneration Ocular gene therapy uses a genetically modified strain of an adeno-associated virus (AAV) as its carrier. This virus “infects” the cells and inserts a “code” that alters the retinal cells’ activity. Treatment aims to slow down macular degeneration, which can cause symptoms such as:blurry visionstraight lines appearing wavya blind spot or dark area at the center of a person’s field of vision AAV is a relatively safe virus approved by the Food and Drug Administration (FDA) for use in ocular gene therapy. Types of macular degeneration Macular degeneration occurs as aging damages the macula, a small light-sensitive portion at the center of the retina responsible for processing detailed, clear vision. The condition typically does not cause total blindness but may cause severe vision problems. There are two types of macular degeneration: dry and wet. The dry type affects 7–9 in 10 people with macular degeneration. People with dry macular degeneration may have tiny clumps of yellow deposits called drusen, causing gradual vision loss. Wet macular degeneration, also called “advanced neovascular macular degeneration,” is less common but more severe. It affects 10–15% of people with macular degeneration. It occurs when abnormal blood vessels behind the retina grow under the macula, causing blood and fluid leakage. These cause scarring and rapid macular damage, leading to loss of central vision. Learn more about the differences between wet and dry macular degeneration. Gene therapy for dry macular degeneration In dry macular degeneration, there is an imbalance in the complement system — a system of proteins in the immune system that fights bacteria and other pathogens. These proteins become overactive and attack the retinal cells, causing membrane attack complex (MAC) or holes in the eye. HMR59 clinical trial There is a clinical trial underway, conducted by Hemera Biosciences, for a therapy called AAVCAGsCD59 (HMR59) for dry and wet macular degeneration. For the procedure, researchers administer an injection of the product into the vitreous cavity of the eye in an office setting. A protein found on the cell surface called CD59 prevents and blocks MACs from forming. This gene therapy permanently alters the retinal cells to increase their expression of CD59. Phase 1 of the therapy has shown efficacy by slowing the rate of progression without producing adverse reactions. GT005 clinical trial Another clinical trial, called GT005 by Gyroscope Therapeutics, also targets MACs. Experts found that complement factor I (CFI) — proteins that prevent the immune system from attacking retinal cells — are low or not functioning in people with dry macular degeneration. Gene therapy delivers a copy of genes that correctly encode this protein and increase its production. This helps counteract the inflammation caused by the complement system and prevents the body from attacking its retinal cells. This therapy is intended to slow the progression of geographic atrophy, which is an advanced form of dry macular degeneration. A 2020 study found that GT005 is safe and well-tolerated in mice, leading to a long-term secretion of human CFI in the animals. Gyroscope Therapeutics also announced positive results from their ongoing Phase 1/2 clinical trial, stating that people tolerated the therapy well and demonstrated increased CFI levels compared with the patients’ baselines. Gene therapy for wet macular degeneration In the wet type, the virus “infects” retinal cells to produce drugs that block VEGF activity, a protein important for the growth of new blood vessels in the eye. There are two clinical trials for wet macular degeneration: Eylea (ADVM-022), conducted by Adverum Biotechnologies, and RGX-314, conducted by Regenxbio Inc. ADVM-022 is in phase 1 trial, while RGX-314 is in phase 1/2. Both are showing high levels of efficacy. There was a reduction in the frequency of annual injections following ADVM-022 injections. Other treatments Treatment for AMD depends on its stage and type. Doctors recommend the following nutritional supplements and lifestyle and dietary changes to help delay the progression of dry macular degeneration:having a balanced diet that includes:yellow fruits and vegetablesgreen leafy vegetablesfishmaintaining healthy cholesterol and blood pressure levelsquitting smokinggetting regular exercisetaking vitamin C, vitamin E, copper, zinc, lutein, zeaxanthin, and beta-carotene supplements Learn about the best vitamins for eye health. Other treatments for dry macular degeneration are in clinical trials but are not yet available for patients. These include lutein supplementation and patient-derived stem cell therapy. Outlook for AMD treatment The potential role of gene therapy is strong based on the promising results of recent and ongoing clinical trials. Aside from this, many preclinical studies also show significant results for treatment options. However, there are still challenges, particularly in delivering the code to the cells. Most research uses AAV vectors, which can vary in their ability to introduce foreign DNA to the retinal cell depending on injection location. Experts are continually exploring new methods of delivering the vector to the back of the eye. Summary Macular degeneration is a progressive eye condition. While it currently does not have a cure, a person may take measures to prevent its progression, including eating a balanced diet, taking supplements, and exercising daily. The field of gene therapy for macular degeneration is rapidly evolving and progressing. If successful, gene therapy can help delay or stop the progression of the disease without the heavy burden of treatment. People wishing to enroll in one of the clinical trials may ask their doctor or get in touch with clinical trials actively recruiting. Last medically reviewed on June 29, 2022Eye Health / BlindnessMedically reviewed by Grace Zhang, MD — By Rachel Ann Tee-Melegrito on June 29, 2022 Latest newsWhat sets 'SuperAgers' apart? Their unusually large neuronsOmega-3 may provide a brain boost for people in midlifeSeasonal affective disorder (SAD): How to beat it this fall and winterCDC: Monkeypox in the US 'unlikely to be eliminated in the near future'Why are more women prone to Alzheimer's? New clues arise Related CoverageCan gene therapy help treat non-small cell lung cancer? Gene therapy involves using specific genes to treat cancer. Learn more about how it works for non-small cell lung cancer, plus other treatment options.READ MOREWhat is exudative macular degeneration? Exudative macular degeneration is a progressive eye disease that causes leaky blood vessels and can lead to vision loss. Learn more.READ MOREInjections for macular degeneration: What to expect Intravitreal injections can greatly improve the symptoms of wet macular degeneration. Read on for what to expect from the use of injections to treat…READ MORECataract surgery and macular degeneration: CorrelationMedically reviewed by Leela Raju, MD Cataract surgery will not affect a person’s risk of developing macular degeneration. Learn more about how the surgery will impact a person's vision. READ MOREBenefits of lutein for macular degeneration Lutein promotes eye health and can help reduce the risk of macular degeneration. Learn more here about the benefits, sources, and more. READ MORE