Choroidal neovascularization is a common eye problem that involves an abnormal collection of blood vessels in the protective layer of eye tissue called the choroid. The condition is closely associated with age-related macular degeneration (ARMD), though it can also occur in young people who suffer eye injuries or infections. Loss of vision is likely if the problem is not recognized and treated right away. Patients are often able to recover some of their vision with medications or corrective surgery.
The choroid is situated just underneath the outermost layer of eye tissue. It is comprised of tiny blood vessels that supply new oxygen to the retina. The inner layer of the choroid, known as the Bruch membrane, also provides protection and cushioning for the inner eye. Choroidal neovascularization occurs when new blood vessels proliferate in the choroid due to a rupture or other abnormality of the Bruch membrane. Doctors do not fully understand why new blood vessels generate, though they have identified several conditions that lead to their development.
Most cases of choroidal neovascularization are secondary to wet ARMD, a condition that begins as blood vessels underneath the retina expand and put pressure on the Bruch membrane, eventually causing irritation or a rupture. Wet ARMD is most likely to affect people over the age of 60. Some instances of choroidal neovascularization result from eye trauma, such as a chemical burn or a shard of glass becoming embedded in the eye. Less commonly, tumors, congenital defects, autoimmune disorders, or infections that reach the eye can damage the Bruch membrane.
The most telling physical symptom of choroidal neovascularization is the gradual worsening of vision. Sight problems usually begin with mild blurring and difficulty focusing straight ahead. In addition, an eye may appear redder than usual as blood and fluid accumulate in front of the retina. Without treatment, blood vessels can eventually displace the retina or cause significant scarring on underlying tissue, leading to total, permanent vision loss.
An eye doctor can usually diagnose the condition by conducting a procedure called a fluorescein angiography. The doctor first injects a fluorescent dye into the choroid, and then takes a diagnostic image using a specialized x-ray machine. The dye penetrates blood vessels and shows up on imaging results, allowing the specialist to determine the nature and severity of the condition.
Treatment for choroidal neovascularization typically involves drug injections, laser surgery, or a combination of the two. A doctor can inject medication directly into the affected choroid to help prevent the further accumulation of new blood vessels. A popular noninvasive procedure called photodynamic therapy involves exposing the choroid to high-intensity light waves in an attempt to ablate blood vessels. In the case of severe choroidal neovascularization, a surgeon may be able to cut into the choroid and manually excise scar tissue. Treatment outcomes vary based on the severity and underlying cause of the condition, but many patients do experience relief following immediate care.