Central Retinal Vein Occlusion - The Evaluation
Learn What to Expect
Learn the fundamentals in less than 15 minutes
Step 1 – Learn the facts
Step 2 – Learn the risk factors for the development of a CRVO and how to decrease the risk of the same problem in the other eye
Step 3 – Learn about the evaluation
Step 4 – Learn about the treatment
Step 5 – Maximizing your vision with treatment
The retina is analogous to the film in a camera. It lines the back wall of the eye and is supplied by an intricate network of arteries and veins.
The retinal arteries and veins share a common tube. The retinal arteries may become harder over time which can lead to the blockage (occlusion) of a retinal vein. There are other less common causes of central retinal vein occlusions which may cause a vein occlusion by a different mechanism.
A central retinal vein occlusion refers to the blockage of the central retinal vein, which is responsible for draining the venous blood from the retina.
There are patients who suffer from a central retinal vein occlusion without any symptoms. However, there are several problems that may develop as a result of this condition. They include macular edema, neovascularization, glaucoma, and ischemia. More about these conditions below.
Macular edema refers to edema (swelling) in the area of the retina responsible for the central vision called the macula. This causes a blurring of the central vision. This condition is treated with intravitreal injections.
Neovascularization is the development of new, abnormal blood vessels. These blood vessels may bleed, causing a vitreous hemorrhage. This condition is typically treated with laser (panretinal photocoagulation), intravitreal injections, or a combination of the two.
Neovascularization may develop in the front of the eye, causing an elevation in the pressure of the eye. This condition may respond well to intravitreal injections or laser in the early phase. In later stages, it may require glaucoma surgery.
Macular ischemia is defined as poor blood flow to the macula. The poor blood flow causes the loss of cells responsible for the central vision. This may result in irreversible vision loss.
Control of high blood pressure is critically important.
Diabetes is present in approximately 10% of cases in patients aged 50 years or older. It is important to be evaluated for the presence of diabetes.
Greater than 90% of all patients are aged 55 years and older.
Optimal cholesterol levels are very important.
High intraocular pressure (ocular hypertension and glaucoma) are risk factors and should be optimized.
There are a number of very uncommon causes of central retinal vein occlusions. The physician will typically order an additional laboratory work-up if there are features to suggest such a cause (e.x young age, both eyes affected, evidence of inflammation)
Learn What to Expect
The eye care specialist examines the eye, looking for abnormal blood vessel growth in the iris. A dilated eye exam is performed and the retina is visualized for signs of a central retinal vein occlusion.
This technology allows the examiner to look at all of the layers of the retina, demonstrating areas of swelling or poor blood flow. It is often repeated to see if new swelling is present or if existing swelling is changing. The image on the top is a normal OCT. The bottom demonstrates a patient with swelling (the black circular areas).
This exam allows the physician to confirm the diagnosis of central retinal vein occlusion by visualizing a delay in the filling of the retinal veins. It is also able to demonstrate areas of new blood vessel growth, sources of edema, and areas of poor blood flow.
The fundamental goals of treatment are to decrease the probability of a central retinal vein occlusion occurring in the other eye by addressing modifiable risk factors mentioned in the previous section.
The goal of treatment of the affected eye is to improve the vision and prevent the development of glaucoma from new blood vessel growth. This is accomplished by treating macular edema with intravitreal injections. New blood vessel growth (if present) is typically treated with laser and intravitreal injections.
The average vision gain after 6 monthly injections is approximately 4 lines on the vision chart (E.X 20/100 to 20/40). Treatments are typically continued monthly until there is no edema. Thereafter, patients will typically receive intravitreal injections at every visit, but the duration between visits will be increased 1-2 weeks as long as there is no recurrence of fluid.
Laser (pan retinal photocoagulation) is directed towards areas of the retina where there is poor blood flow. The laser typically takes 5-10 minutes and is completed either in one session, or the patient may be asked to return another day. The laser procedure is not designed to improve the vision, but to encourage the regression of the new blood vessel growth.
It is important to follow-up at scheduled appointments. Missing 1 appointment for treatment of macular edema can cause a significant decline in vision which may take months to recover.
Optimize the risk factors for the development of a central retinal vein occlusion to decrease the risk of a central retinal vein occlusion in the other eye
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