• Reference Number: HEY-266/2013
• Departments: Ophthalmology Department
• Last Updated: 31 May 2023

Introduction

This leaflet has been produced to give you general information about your treatments.  Most of your questions should be answered by this leaflet. It is not intended to replace the discussion between you and your doctor, but may act as a starting point for discussion.  If after reading it you have any concerns or require further explanation, please discuss this with a member of the healthcare team.

What is a Central Retinal Vein Occlusion?

When the main vein (central retinal vein) of the eye draining blood from the eye gets blocked, it is called a central retinal vein occlusion (CRVO). The blockage of the vein means that blood cannot drain out of the retina (film at the back of eye where the image forms). This leads to reduced vision due to:

• Build-up of blood and other fluid causing the retina to get ‘waterlogged’ (macular oedema). Waterlogging and the lack of oxygen damages the light receptors at the central retina (the macula), causing the central vision to be blurry. This is the most common cause of visual loss in vein occlusion.

• Some people unfortunately suffer severe damage to the blood supply (macular ischaemia) at the back of the eye causing a permanent loss of vision.

• About 30% people with a CRVO develop abnormal blood vessels either on the iris, the coloured part of the eye, or on the surface of the retina itself. These abnormal vessels can bleed or cause an inflamed painful eye with a marked rise in eye pressure leading to further loss of vision.

What causes a CRVO?

A CRVO is more common in people as they get older, especially over the age of 60. There are some conditions that we know can make it more likely to happen such as:

• High blood pressure
• Diabetes
• High cholesterol
• Smoking
• Glaucoma
• Inflammatory diseases of the eye

The doctor who sees you will organise some tests to see if a cause can be found in your case, although a cause may never be found out.

Why do I need treatment?

Each case of retinal vein occlusion is unique. The mild cases of vein occlusion may get better without treatment but only 10 – 20% of cases with severe occlusion may recover some vision. The majority of patients with CRVO do not recover vision and often get worse if left untreated for several months. This is due to development of irreversible scarring. There is some evidence that delaying treatment for months may reduce the chances of visual recovery.

If you develop abnormal blood vessels on the coloured part of the eye then delaying treatment results in severe and painful loss of vision.

What treatment is available?

Some patients cannot be treated as they suffer severe damage to the blood supply at the back of the eye resulting in a permanent loss of vision.

You may however be offered treatment in the following situations.

1. If you develop new blood vessels on the iris or retina, as mentioned above, then you may need laser treatment, called panretinal photocoagulation. This laser treatment protects the eye against a sudden further decrease in vision due to bleeding into the vitreous gel of the eye and prevents painful increase in eye pressure (Neovascular Glaucoma). This form of laser treatment has no effect on macular oedema. For more information see ‘Panretinal Photocoagulation Laser Treatment’ leaflet.
2. If you develop waterlogging of the central part of the eye i.e. macular oedema, then you may be offered injections of various drugs into the eye of which there are two main types: 
   • Steroid Implant – Ozurdex (Dexamethasone)
   • Anti-VEGF Agents – Lucentis (Ranibizumab), Eylea (Aflibercept), Avastin

   These drugs are given as intravitreal injections, which means that they are injected into the eye.

• Ozurdex is the trade name of the drug dexamethasone, a type of steroid. The Ozurdex implant is injected into the eye and slowly releases the drug as it dissolves (biodegrades). The implant is usually invisible to the patient. The drug reduces water-logging of the macular by reducing inflammation associated with the vein occlusion. Ozurdex is licensed for use in vein occlusion patients and has been extensively studied in research clinical trials. The effect of Ozurdex implant lasts for 4-6 months so the implant must be repeated regularly over a 2-3 year period as a minimum.
• Anti-VEGF Agents; Lucentis (Ranibizumab), Eylea (Aflibercept) and Avastin (Bevacizumab). These drugs block the action of a molecule VEGF in the eye which make blood vessels leaky and so cause waterlogging of the macula. VEGF production increases in the eye after a vein occlusion. Lucentis and Eylea are licensed for use in vein occlusion patients and have been extensively studied in research clinic trials. The effect of Lucentis and Eylea is temporary so they must be given repeatedly over a year or more.                                                                                                                                                                    Patients receive first 4 injections (anti-VEGF), 1 injection every month, as an automatic loading dose. Patients get eye scan and vision test every visit and this information is used to decide about the spacing between further injections after the loading dose.
• Avastin (Bevacizumab) is an Anti-VEGF agent and has been shown to have effects similar to Lucentis and Eylea but is not licensed for use in the eye.

Will the treatment help?

Regardless of the type of injection used, in research trial, the injection treatment double the chance of gaining 3 lines or 15 letters of vision compared to those not treated. The research has also shown that early treatment gives greater improvement in vision. Your own result may vary.

Can there be any complications and risks?

Regardless of the drug is used, each injection procedure carries a small risk (1 in 1000 patients) of serious complication including infection inside the eyeball (endophthalmitis) which can potentially result in total loss of vision if not treated promptly (see Information for Patients Under-Going Intravitreal Injections leaflet).

Ozurdex implant has associated risk of developing cataract (6 times more likely to develop cataract but can be treated with cataract surgery) and glaucoma i.e. raised pressure in the eye (about 1 in 4 patients needed eye drops for the pressure in their eye after 6 months and a very small number, needed surgery to reduce the pressure in the eye).

There are no proven risks to your general health with these injection treatments.

None of the injection treatments have been tested on pregnant women and therefore should be used with caution in women of child bearing age.

For some patients the risks of treatment will outweigh the benefits and for others the eye may be too badly affected to make treatment worthwhile. Your doctor will discuss all the risks and benefits with you.

How do I come prepared for treatment?

Please read the information leaflet.  Share the information it contains with your partner and family (if you wish) so that they can be of help and support.  There may be information they need to know, especially if they are taking care of you following this examination.

Please eat and drink as usual on the day of the treatment. Please bring your usual diabetic medications with you, especially insulin, if the timing of your visit coincides with your usual medication times. It would be sensible to bring a snack in case of any delays, although this is unlikely to happen.

Please do not drive to your appointment as you will be having dilating drops in your eye/s under-going treatment and should not drive for up to 6 hours afterwards as your vision will be blurred.

The treatments are all done as day case/ out-patient procedures and you will not be staying in hospital over-night

What will happen?

When you attend for an injection appointment please report to the Main reception Desk in the Eye Hospital. You will be directed to the correct waiting area. This will be in the Eye Clinic for Anti-VEGF injections and will be in the Day Case area on the 1^st Floor for Ozurdex injections.

A nurse will check your details with you and you will have dilating drops in the eye/s to be treated. You will also have a vision test and an eye scan if you are having Lucentis or Eylea injection treatment. 

Laser treatment (see additional leaflet on Panretinal photocoagulation):   This is performed in the eye clinic and for many patients is a one off treatment although some require a repeat treatment.

The pupil is dilated and then anaesthetic drops are used to numb the eye. You will be asked to place your chin onto a rest, similar to the one that you will have been used to being examined on in clinic. A contact lens is then placed on the eye to focus the laser and the laser is shone repeatedly into the eye. Each shot of the laser is seen as a burst of bright light. The treatment will take about 30 minutes and, although this is dazzling, there is no pain.

You will be able to go home the same day although your vision will be dazzled in this eye for several hours.

Injection Treatment

The injection treatment would be performed in the theatre or in a clean room in the eye clinic. The pupil is dilated and your eye will be numbed using local anaesthetic drops   or in case of Ozurdex implant sometimes a local anaesthetic injection is used. The injection is performed with you reclining on a couch, the eyelids are cleaned and cleaning solution is used in the eye and a sheet placed over the eyes/forehead. The injection is given from the side so that you will not be able to see the procedure, although you may be aware of pressure on or around the eye. You will be able to go home the same day.

After the Ozurdex implant you will have regular review to monitor response to treatment and to check the pressure in the eye and you may need to have the treatment repeated every 4 to 6 months for up to 3 years, depending upon the response to treatment.

In case of Anti VEGF injection, the doctor will decide the review interval based on response to the loading dose of 4 injections. On some of the visits, you will just have the tests which the doctor will analyse later and you will be informed of the treatment decision through a telephone call.

What happens afterwards?

Immediately after the injection, your eye may feel slightly sore/ watery and may be blood shot but this is normal and these symptoms will soon wear off. Your vision will be blurred until the effect of dilating drops has worn off.

You will be given instructions about what to do if you think there is a more serious problem with your eye after the injection. You will also be given emergency contact telephone numbers before you leave the department. 

Should you require further advice on the issues contained in this leaflet, please do not hesitate to contact the Ophthalmology Department on (01482) 608788

General Advice and Consent

Most of your questions should have been answered by this leaflet, but remember that this is only a starting point for discussion with the healthcare team.

Consent to treatment

Before any doctor, nurse or therapist examines or treats you, they must seek your consent or permission. In order to make a decision, you need to have information from health professionals about the treatment or investigation which is being offered to you. You should always ask them more questions if you do not understand or if you want more information.

The information you receive should be about your condition, the alternatives available to you, and whether it carries risks as well as the benefits. What is important is that your consent is genuine or valid. That means:

• you must be able to give your consent
• you must be given enough information to enable you to make a decision
• you must be acting under your own free will and not under the strong influence of another person

Information about you

We collect and use your information to provide you with care and treatment. As part of your care, information about you will be shared between members of a healthcare team, some of whom you may not meet. Your information may also be used to help train staff, to check the quality of our care, to manage and plan the health service, and to help with research. Wherever possible we use anonymous data.

We may pass on relevant information to other health organisations that provide you with care. All information is treated as strictly confidential and is not given to anyone who does not need it. If you have any concerns please ask your doctor, or the person caring for you.

Under the General Data Protection Regulation and the Data Protection Act 2018 we are responsible for maintaining the confidentiality of any information we hold about you. For further information visit the following page: Confidential Information about You.

If you or your carer needs information about your health and wellbeing and about your care and treatment in a different format, such as large print, braille or audio, due to disability, impairment or sensory loss, please advise a member of staff and this can be arranged.