What is Retinal Vein occlusion?
Retinal vein occlusion is as the name suggests occlusion of the vein that drains the retina. It can result in permanent visual changes if the occlusion involves the central retinal vein or one of its major branches. It can occur as a consequence of long-standing hypertension, glaucoma, diabetes, high body mass index, and even cardiovascular diseases.
Patients with this condition present with acute loss of vision with no prior warning signs.
Currently used treatments for retinal vein occlusion target the fluid leakage from occluded blood vessels and neovascularization. However, these treatments demand multiple direct injections into the eye. currently relies on drugs that reduce fluid leakage from blood vessels and abnormal blood vessel growth. Despite the daunting procedure, the treatment doesn’t reverse or prevent vision loss.
As of now, there are no available treatments that can reverse the damage caused by retinal venous occlusion. Treatments such as anti-VEGF drugs are aimed at preventing the progression of macular edema and iris neovascularization but it doesn’t restore lost vision.
Due to the poor and variable prognosis of this condition despite treatment, preventing retinal venous occlusion is the major target in people with risk factors. However, simply lowering the threshold of the risk factors such as by controlling blood pressure or blood sugar levels may not be enough to prevent veinous occlusion due to its multifactorial pathophysiology.
Researchers from the Columbia University Irving Medical Center have made groundbreaking findings with the development of an eye drop that could potentially prevent vision loss even after retinal vein occlusion has already occurred.
An experimental treatment on mice with retinal artery occlusion by targeting the underlying common neurodegenerative and vascular leakage in the eye may have the answers to the prevention of vision loss despite retinal vein occlusion.
The researchers targeted an enzyme known as caspase-9 which is said to be a key factor in apoptosis that is programmed cell death. It is a normal physiological process by which the body eliminates abnormal cells.
Studies on mice revealed that caspase-9 becomes abnormally activated beyond control in blood vessels that have been damaged by retinal vein occlusion. This uncontrolled caspase-9 activity can trigger damage to the retina which results in vision loss.
Eye Drops That Prevent Vision Loss
By using eye drops that contain caspase-9 inhibitor, retinal function was found to be improved in mice models of retinal vein occlusion. In addition, the eye drops minimized edema, ischemia, and nerve damage by improving blood flow.
The highly selective caspase-9 inhibitor may have applications other than for retinal artery occlusions such as stroke and diabetic retinopathy. The researchers plan to begin testing the caspase-9 inhibitor during phase I clinical trials soon.
“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, Ph.D., a postdoctoral research scientist in pathology & cell biology at Columbia University Vagelos College of Physicians and Surgeons.