Eye care advancements continue to revolutionise the treatment of various eye conditions, particularly age-related macular degeneration (AMD). A recent experiment on mice has opened the doors for a possible new treatment route for the wet form of AMD.
AMD is a common eye condition that affects a tiny part of the retina at the back of the eye, known as the macula. The wet form of AMD, also referred to as neovascular AMD, is less common but more severe. It is characterised by the growth of new, abnormal blood vessels that invade the retina, causing blurred central vision.
The study, led by Nagaraj Kerur, associate professor of ophthalmology and visual sciences at The Ohio State University College of Medicine, focused on the role of an enzyme called telomerase in the development of wet AMD. Telomerase is linked to cell growth and division, and previous cancer research has connected high telomerase activity with rapid production and migration of cells lining blood vessels that promote tumour growth.
In the study, the researchers induced rapid growth of new blood vessels in mice using a laser. They discovered that expression and activity of one of the two genes carrying instructions for making telomerase were higher in the eyes of these mice. The abnormal blood vessel response to the laser injury was significantly lower in mice lacking both telomerase genes, making a strong case for telomerase’s role in the disease’s development.
The team then applied an experimental drug that inhibits telomerase activity. They found that injecting this drug into the eyes of mice with symptoms similar to wet AMD significantly reduced the abnormal blood vessel invasion.
The current treatment for wet AMD involves injecting a medication into the eye that blocks the activity of a growth factor protein known as VEGF, which is known to trigger abnormal blood vessel growth. However, this treatment has its limitations. After two years, about half of the patients stop responding, and some develop scarring under the retina.
The effectiveness of the experimental treatment in reducing abnormal blood vessel growth in mice was similar to the current anti-VEGF treatment. But an interesting finding emerged when both drugs were tested at lower doses. Each drug alone at a lower dose did not have much of a therapeutic effect, but a combination of both drugs at lower doses yielded the best results.
Kerur suggested that a potential goal could be using combination therapy rather than just one drug. However, he also stated that telomerase inhibition could also be pursued independently.
This promising research, supported by National Institutes of Health grants, the Ohio Lions Eye Research Foundation, and a Research to Prevent Blindness grant, could potentially lead to more effective treatment options for wet AMD in the future. This can be a game-changer for many patients suffering from this condition, opening up the possibility of better vision and quality of life.
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