Retinal Vein Occlusion
What is a retinal vein occlusion?
The retina consists of a fine network of blood vessels and nerves. A retinal vein occlusion results in an abnormality of the blood flow through these vessels, accompanied by bleeding on the retina surface and swelling of the nerve fibre layers at the macular (macular oedema). The occlusion may involve the main blood vessels that supply the retina (central retinal vein occlusion) or a smaller branch of the main blood vessels (branch retinal vein occlusion).
This may result in your vision becoming suddenly reduced or it may sometimes be an abnormality that the optician notices at a routine sight test.
What causes a retinal vein occlusion?
The exact cause is unknown. Patients with glaucoma are at higher risk of developing vein occlusions. There are also several conditions in the body that increase the risk of a vein occlusion. The highest risk is associated with uncontrolled blood pressure and raised blood cholesterol. There are several other conditions that will be tested for with appropriate blood tests including thyroid disorders, problems with blood viscosity and if indicated, factors that affect blood clotting. These will be discussed with you at your consultation to determine what is right for you.
Symptoms of a retinal vein occlusion:
If the central retina is affected, you may notice that the distance eyesight or reading vision becomes suddenly reduced. It may appear blurred or a dark patch may suddenly appear. Distortion (straight lines looking curved or crooked) may also be a problem.
What will happen at my consultation?
Your consultation in our clinic in London will consist of a discussion with your doctor and a thorough eye examination. You will then have an OCT scan and some patients may need a fluorescein angiogram as well. More information about these tests can be found in the patient information section above.
If the tests find evidence of macular oedema, you will be offered urgent treatment that can take place the same day (if you are insured, your insurer will need to approve this first).
Treating retinal vein occlusions:
If macular oedema is identified, it is important to treat this as soon as possible to give the best chance of improving and protecting your vision. The two main methods of treating macular oedema are either injections into the eye or laser treatment to the retina. Your doctor will advise you of the best choice for you.
The different drugs that are used to treat macular oedema include anti-vascular endothelial growth factor (Anti-VEGF) drugs (Lucentis, Eylea or Avastin) and steroid drugs (Ozurdex or Iluvien). They have different advantages and side effects and choosing the right drug for you will depend on your individual needs. Your doctor will advise you of this.
Having an injection is not painful. The eyelids are cleaned with Iodine and local anaesthetic eye drops will be applied to the eye. A speculum is used to keep the eye open and the injection is given with a very fine needle (almost as thin as an eyelash). You will feel a sensation of pressure (like a finger pressing on the eye) but this will not feel sharp or painful. The whole process takes less than 10 minutes. Most patients will require a course of injections ranging from 3-8 in one year.
What to expect after the injection:
The eye will feel like it has a small piece of grit under the lids. This is where the needle entered the eye. This sensation will usually pass within a day and can be easily managed by using artificial tear drops.
There may be a small blood spot on the eye surface where the needle entered the eye. This is harmless and will disappear after about a week.
Immediately after the injection, you vision may be blurred. This will resolve within a few hours.
You can assume all normal tasks after an injection. However, it is important to avoid contaminating the eye surface with unclean water or dirt. Patients are advised not to perform tasks such as gardening or swimming for 1 week.
If you were treated with a steroid implant, you may notice a floater in the shape of a line. This is the shadow cast from the implant if it is floating near the centre of the eye. This is a temporary symptom and will usually fade with time.
There is a 1:1000 risk of developing a sight-threatening infection after an injection into the eye. This is very rare but needs to be treated urgently. If you develop either worsening pain, worsening redness of the eye or worsening vision in the first 10 days after an injection, you must contact your doctor immediately.
A laser is a highly focussed beam of light that is used to reduce the leakage from damaged blood vessels in the retina. A special contact lens is placed on the eye surface to help focus the laser on the correct area of the retina to be treated. Laser treatment cannot be given if there is blood on the retina surface (common in the first 3 months after a vein occlusion). It also cannot be used effectively to treat macular oedema that involves the fovea (the specialised part of the retina that is needed to see fine detail, such as reading). Under these circumstances, patients will need to be treated with intravitreal injections, as detailed above.
Laser still can offer some advantages such as less frequent treatment and it is not a surgical procedure, so there is no risk of infections that can cause blindness. It can also help to reduce the need for repeated injections.
Important points to remember:
The visual loss following a retinal vein occlusion can be managed well if treated early, which will help ensure the best visual outcome.
Controlling risk factors such as blood pressure, raised cholesterol or smoking is important in preventing any further vein occlusions from developing that could cause further loss of sight.
There are several treatment options for macular oedema that consist of injections into the eye or retinal laser. The indications will vary for each individual patient and your doctor will discuss these with you.