WHAT IS THE RETINA?
THE RETINA is a thin layer of light-sensitive nerve tissue that lines the back of the eye (or vitreous) cavity. When light enters the eye, it passes through the iris to the retina where images are focused and converted to electrical impulses that are carried by the optic nerve to the brain resulting in sight.
OCT of an acute CRVO with severe macular edema. Image courtesy of John Thompson, MD to assess closure of small blood vessels, or to search for or confirm growth of new abnormal vessels, fluorescein angiography (FA) imaging may be performed.
Prognosis and Treatment: CRVO has a better prognosis in young people. In older patients who receive no treatment, about one-third improve on their own, about one-third wax and wane and stay about the same, and about one-third get worse. If there is macular edema, it may improve on its own.
In patients with CRVO, vascular endothelial growth factor (VEGF) is elevated; this leads to swelling as well as new vessels that are prone to bleeding. The most common treatment, based on results from powerful randomized clinical trials, involves periodic injections into the eye of an anti-VEGF drug to reduce the new blood vessel growth and swelling. Anti-VEGF drugs include bevacizumab (Avastin®), ranibizumab (Lucentis®), and aflibercept (Eylea®).
Although anti-VEGF drugs reduce the swelling, they are not a cure. As the drug leaves the eye and moves into the bloodstream, the effect in the eye wears off, so re-injection is often needed. A rare lucky patient needs only one injection, but the norm is a series of periodic injections over the course of a few years.
Another option for treating macular edema from CRVO is with an injection of intraocular steroid. This could be either a liquid steroid called triamcinolone or a small steroid pellet called dexamathasone implant (Ozurdex(R)). The steroid injections typically last several months, but can cause elevated intraocular pressure requiring eye drops or increased rate of cataract formation.
Ischemic (pronounced is KEY mick) and Non-ischemic CRVO:
CRVO comes in 2 types:
Patients with ischemic CRVO have worse vision with less chance for improvement. They have a tendency for the eye to cause new blood vessels to grow—and in the front of the eye, these new vessels can clog the outflow of normal eye fluids. The eye pressure goes up and glaucoma develops. In the back of the eye, new blood vessels may cause bleeding.
When there is ischemic CRVO with new vessels, anti-VEGF injec- tions lead to prompt, but often temporary, control of the new ves- sels. Laser treatment tends to offer a more permanent effect. In some cases, both treatments are used.
Non-ischemic CRVO can worsen and become ischemic, so when CRVO is diagnosed, monthly checkups are initially recommended.
It’s important to note that early detection of macular edema or abnormal blood vessels is important; most patients can avoid severe vision loss if treatment is begun before substantial damage develops in the eye.
S YMPT OMS
Mild CRVO may show no symptoms. However:
Patients with severe CRVO and secondary complications such as glaucoma (a disease characterized by increased pressure in the eye) often have pain, redness, irritation and other problems.
THANK YOU TO THE AUTHORS
Sophie J. Bakri, MD Audina Berrocal, MD
Thomas Ciulla, MD, MBA Geoffrey G. Emerson, MD, PhD Roger A. Goldberg, MD, MBA Dilraj Grewal, MD
Larry Halperin, MD Vi S. Hau, MD, PhD
G. Baker Hubbard, MD Talia R. Kaden, MD
M. Ali Khan, MD
Mathew J. MacCumber, MD, PhD Timothy G. Murray, MD, MBA Oded Ohana, MD, MBA Jonathan L. Prenner, MD
Carl D. Regillo, MD, FACS Naryan Sabherwal, MD Sherveen Salek, MD Andrew P. Schachat, MD Michael Seider, MD
Janet S. Sunness, MD Edward Uchiyama, MD Allen Z. Verne, MD Christina Y. Weng, MD, MBA Yoshihiro Yonekawa, MD
John T. Thompson, MD
MEDICAL ILL US TRAT OR