This story is part of a series on current advances in regenerative medicine. This piece is part of a series dedicated to improving the eyes and restoring vision. This article also marks the first part of a short series on diabetic retinopathy.
In 1999, I defined regenerative medicine as a collection of interventions that restore normal function to tissues and organs damaged by disease, injured by trauma, or worn out over time. I include a full spectrum of chemical, gene and protein-based drugs, cell-based therapies, and biomechanical interventions that achieve that goal.
Diabetic retinopathy, a condition that develops in people with diabetes, is a silent thief that takes away their vision. It is one of the leading causes of blindness in the working population worldwide and its prevalence is continuously increasing. In 2021, diabetic retinopathy affected an estimated 9.6 million people in the US, comprising 26.43% of people with diabetes.
With such worrying statistics, it is important to understand the current treatment options available to these individuals. From novel drug treatments to clinical trials and gene therapy, the field of ophthalmology has made significant progress over the years in treating this debilitating disease.
What is diabetic retinopathy?
Diabetic retinopathy is a diabetes-related complication that affects the blood vessels in the retina. The retina, located at the back of the eye, is responsible for visual perception. High blood sugar levels can damage the blood vessels in the retina, causing a number of symptoms and complications. The disease can progress through two main stages: non-proliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR), with the latter being more severe.
Several factors can increase the risk of developing diabetic retinopathy. These include uncontrolled blood sugar levels, high blood pressure, high cholesterol, obesity, pregnancy and smoking. As the duration of diabetes increases, the likelihood of diabetic retinopathy also increases. Timely recognition and intervention is important to prevent vision loss and reduce the complications associated with this disease.
Several pathways and mechanisms have been identified that play important roles in the development and progression of diabetic retinopathy. A study from the University of Malaya outlines these pathways and mechanisms. One of the important pathways is the polyol pathway, which converts excess glucose into sorbitol and fructose. This process causes osmotic stress and oxidative damage to the retina.
Another important pathway is the protein kinase C (PKC) pathway, which produces vascular endothelial growth factor (VEGF), leading to abnormal retinal growth. In addition, non-enzymatic glycation, inflammation, oxidative stress and activation of the renin-angiotensin system (RAS) are also involved in the development of diabetic retinopathy. Failure to address these pathways and mechanisms can result in retinal damage and vision loss if not addressed.
Current treatment for diabetic retinopathy
Managing this condition effectively requires maintaining tight control over blood sugar and blood pressure levels. This is usually the first course of action that most doctors recommend to stop or slow the progression of the disease. Early detection can help slow its passage in the early stages by closely monitoring your blood sugar and blood pressure.
Laser treatment is often used in later stages to stop further damage and prevent vision loss. It targets and stops the growth of new, delicate blood vessels that can cause bleeding within the eyes. This process involves several treatments that may be necessary to ensure the best results, and the frequency of treatments depends on the severity of the condition. It is a safe and effective outpatient procedure that does not require hospitalization. However, laser treatments are limited in their ability to restore already lost vision and may cause some degree of vision loss after the procedure due to the destruction of healthy tissue in the treated area.
When laser treatment fails, or in cases of advanced retinopathy, anti-VEGF medication is a viable treatment option. These medications are injected directly into the gel-like substance in the eye called the vitreous, which helps prevent the growth of new blood vessels and reduce fluid buildup. Anti-VEGF medication works by blocking the action of the VEGF protein, which stimulates the growth of new blood vessels in the retina. As a result, anti-VEGF medication can prevent abnormal blood vessel growth in the retina. Anti-VEGF treatment for diabetic retinopathy requires frequent and expensive injections, creating compliance and access problems for some patients.
Another option is steroids. Steroid implants may be placed in the eyes to reduce inflammation and swelling that can cause vision loss in patients with diabetic retinopathy, especially those with macular edema. In cases where laser treatment is not an option due to the severity of the retinopathy, eye surgery may be performed to remove blood clots or scar tissue that has accumulated in the eye due to the retinopathy. This procedure may help restore vision in less severe cases of diabetic retinopathy. It is important to mention that steroid implants can be useful for treating diabetic retinopathy, but they come with some limitations. They can cause increased intraocular pressure, cataract formation, and other complications that require careful monitoring and management by a qualified health care professional.
State-of-the-art treatment options
In addition to the standard treatments currently available for diabetic retinopathy, researchers are exploring new and innovative ways to combat this eye disease. One such cutting-edge treatment is gene therapy, which involves inserting healthy genes into the retina to replace the faulty genes responsible for the development of diabetic retinopathy. Although gene therapy is still experimental, it has shown promising results in the treatment and management of this condition.
Another potential treatment option being explored by researchers is stem cell therapy. It involves replacing damaged or dead cells in the retina with stem cells. However, there are some challenges that limit its effectiveness, such as the risk of immune rejection of transplanted cells, difficulties in selecting the appropriate type of stem cells, and the possibility of tumor growth. Although still in the early stages of development, stem cell therapy holds great promise as a future treatment option for individuals with diabetic retinopathy.
Researchers are also investigating using a protein called NOX4 as a potential therapeutic target for diabetic retinopathy. NOX4 is recognized for its involvement in the development of this disease. By targeting this protein, researchers hope to develop new treatments to effectively manage and treat diabetic retinopathy.
Overall, ongoing research into new treatments for diabetic retinopathy provides hope for individuals suffering from this condition and may lead to more effective treatments and better outcomes in the future.
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