NEW YORK — They say the eyes are a window to the soul, but they’re also a doorway to the world. More so than smell, sound, taste, and touch, our vision allows us to experience and understand our environment. It’s an ability that’s easily taken for granted, but there’s also perhaps no scarier thought than the idea of losing one’s sight.
One of the leading causes of blindness is a condition called retinal vein occlusion or RVO. It’s an affliction that causes millions to lose their sight each year. Luckily, researchers from the Columbia University Irving Medical Center just developed a new type of eye drop potentially capable of preventing blindness as a result of the condition.
RVO occurs when a major blood-draining vein in the retina is blocked. Most often, this happens as a result of a blood clot. When this occurs, it can lead to blood and other fluids leaking into the retina, which in turn causes significant damage to specialized light-sensing neurons called photoreceptors.
Most typical treatments for RVO primarily involve drugs that decrease blood vessel leakage and stop abnormal blood vessel growth. But, these drugs come with noticeable negatives as well. To start, these approaches require multiple injections be made directly into one’s eyes. Ouch. Making matters worse, in the majority of cases these injections don’t actually prevent eventual blindness.
Eye drops stop damage from RVO in mice
These new eye drops, on the other hand, target an enzyme called caspase-9. Normally, caspase-9 is responsible for “programmed cell death,” a natural bodily mechanism focused on doing away with damaged or excess cells. But, over the course of the researchers’ experiments involving mice, it was noted that whenever blood vessels are injured by RVO, nearby caspase-9 enzymes become overactive, ultimately damaging the retina.
So, essentially these eye drops deliver a caspase-9 inhibitor that shuts the enzymes down, neutralizing the detrimental effects and subsequent blindness caused by RVO.
More specifically, when mice with retinal vein occlusion were given the eye drops a number of visual improvements were noted. The mice also saw their swelling go down, blood flow improve, and a reduction of neuronal damage in the retina.
Seeing a bright future
“We believe these eye drops may offer several advantages over existing therapies,” explains Dr Carol M. Troy, a professor of pathology & cell biology, and of neurology in the Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, in a university release. “Patients could administer the drug themselves and wouldn’t have to get a series of injections. Also, our eye drops target a different pathway of retinal injury and thus may help patients who do not respond to the current therapy.”
Moving forward, the research team is already preparing to hold trials with human subjects. There also may be potential for the caspase-9 inhibitor to be used as a treatment for other issues like diabetic macular edema or stroke.
“Vascular dysfunction is at the heart of many chronic neurological and retinal disorders, because high energy demands in the brain and eye render these tissues exceptionally vulnerable to disruption in blood supply,” says the study’s first author, Maria Avrutsky, PhD, postdoctoral research scientist in pathology & cell biology at Columbia University Vagelos College of Physicians and Surgeons.
The study is published in Nature Communications.