- Reference Number: HEY485/2026
- Departments: Ophthalmology Department
- Last Updated: 30 September 2026
Introduction
This leaflet has been produced to give you general information. Most of your questions should be answered by this leaflet. It is not intended to replace the discussion between you and the healthcare team 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 Diabetic Macular Oedema?
Diabetic Macular Oedema (DMO) is a condition affecting the retina – the nerve layer at the back of the eye. The retina is a thin layer of nerve cells similar to the film in a camera and, in order to function, it needs to remain as a thin healthy layer. The central part of the retina is known as the macula. The macula is responsible for fine detail vision, both for near (reading) and for distance (television / driving).
In patients with DMO, the fine meshwork of blood vessels supplying nutrients and oxygen to the macula become damaged and leaky due to the high levels of glucose in the bloodstream in some patients with Diabetes. The damaged tiny blood vessels allow fluid from the bloodstream to leak into the retinal nerve layer so that it becomes waterlogged and unable to function. If this happens in the macular area, the vision may be damaged, especially if the centre of the macula (known as the fovea) is affected, as this is the most sensitive part of the retina for detailed vision.
DMO can be divided into two types:
- “Centre-involving DMO”– where the fovea and/ or immediate area around the fovea is affected.
- “Non-centre involving DMO” also known as “extra-foveal DMO”.
There is a third type of diabetic macular damage (ischaemic maculopathy) where the meshwork of tiny blood vessels supplying the macular area shuts down due to the high glucose levels in the bloodstream in Diabetes. This closure of the blood vessels starves the retina of its blood supply, causing eyesight loss. This disease process is currently not treatable.
The type of DMO you have is determined by a combination of examination of the eye on a slit-lamp machine in the clinic, the result of the Optical Coherence Tomography (OCT) scan done at the clinic visit and sometimes by the use of a Fluorescein Angiogram (dye test). Treatments for the different types of DMO varies depending on whether the DMO is centre-involving or non-centre-involving and the extent of the DMO. The most appropriate treatment for your type of DMO will be discussed with you.
Patients may be unaware that diabetic macular oedema (DMO) is happening in the early stages, as the vision is not affected straightaway. This is why Diabetic Eye Screening is important to detect these changes at an early stage to prevent loss of vision. Other patients may be aware of symptoms of blurring of the central detailed vision or distortion of the vision.
Why do I need treatment for Diabetic Macular Oedema (DMO)?
If left untreated, the leakage will potentially permanently damage the retinal nerve cells and eventually produce scarring, which is currently irreversible. In this advanced disease, the patient would have no detailed central vision but would keep their field of vision and so still be able to catch sight of objects “out of the corner of their eye”.
This leaflet is intended for patients who have been told they have centre-involving diabetic macular likely to benefit from treatment. Information about the treatment for non-centre involving DMO can be found in the Macular Laser information leaflet.
What treatments are available for centre-involving Diabetic Macular Oedema?
Currently there are a number of recommended (NHS / NICE approved) treatments for advanced “centre-involving DMO”. The actual clinical decision about which of these treatments is best for you in your individual circumstances will be discussed with you in the clinic. In some cases, there may be a choice of treatments, and your doctor will explain the risks and benefits of the suitable options to help you decide which treatment you would prefer to have.
Anti-VEGF injections, including Aflibercept 2 mg biosimilar (Eydenzelt), Faricimab (Vabysmo), Aflibercept 8mg (Eylea HD), Ranibizumab biosimilar (Rimmyrah)– These drugs block the action of a molecule, Vascular Endothelial Growth Factor (VEGF), in the eye which makes blood vessels leaky and so cause waterlogging of the macula. are licensed for use in wet AMD and have been extensively studied in research clinic trials. There is no evidence that one drug produces better vision than the other. The effect of these injection treatments is temporary so they must be given repeatedly potentially for several years. Patients receive three injections, 1 injection every month, as an automatic loading course. Patients will have an eye scan and vision test every visit and this information is used to decide the spacing between further injections after the loading dose. These injections are given over a prolonged period depending on how well the eye responds.
Aflibercept 2 mg Biosimilar (Eydenzelt) is a copy of original Aflibercept, manufactured by different pharmaceutical companies. This is shown to have the safe safety and effectiveness s original Aflibercept but more cost effective. There is a mandate from NHS England that all patients should be commenced on Aflibercept 2 mg biosimilar (Eydenzelt) unless they meet certain exclusions.
Faricimab (Vabysmo) is an anti-VEGF drug which is in use since 2022, licensed for use in DMO. Apart from blocking the VEGF molecule, it also blocks another molecule called Angiopoietin-2. Current evidence suggests that Vabysmo may last for longer than the other anti-VEGF drugs, potentially reducing the required number of injections over a period.
Aflibercept 8mg (Eylea HD) is a newer anti VEGF which became available from 2024 and is a licensed for use in DMO. This is a larger dose of Aflibercept (8 mg versus 2 mg) and requires larger volume to be injected into the eye. There is evidence that Eylea HD may last for longer than the other anti-VEGF drugs, potentially reducing the required number of injections.
Ranibizumab Biosimilar (Rimmyrah), which is a similar copy of the original Ranibizumab, manufactured by different pharmaceutical companies is also available for use. This is shown to have the same safety and effectiveness as original Ranibizumab but less expensive. This has shortest duration of action of all the drugs available. We currently do not offer this drug as first line agents unless specifically indicated.
Ozurdex (Dexamethasone) is a different class of steroid based drug. It is given as an injection of dissolving steroid pellet into the eyeball, which slowly releases the steroid drug over a period of 3 to 6 months. The implant is usually invisible to the patient. The drug reduces waterlogging of the macula by reducing inflammation.
In patients with longstanding centre-involving DMO which has not responded to standard treatment with anti-VEGF injection treatment or requiring multiple Ozurdex injections, treatment with Iluvien (Fluocinolone acetonide) is sometimes appropriate. Iluvien is a steroid-releasing implant which is given as an injection into the eyeball and may last for up to 3 years.
With all of these drugs used to treat DMO each patient has a:
- 9 out 10 chance of stabilising the vision (preventing further significant loss of vision)
- 1 in 3 chance of a big improvement in vision i.e. of regaining a large amount of the vision that has been lost.
- This compares to around a 13 / 15 out of 100 chance of a similar improvement with Laser alone
There is good evidence that maintaining good diabetic and blood pressure control can help to prevent the development of DMO and stabilise existing DMO, although this alone (without drug or laser treatment) may not be enough to improve DMO. You are advised to see your GP or Diabetologist on a regular basis for monitoring of your diabetes.
Can there be any complications or risks?
Like all medicines, anti-VEGF treatment can cause side effects, although not everybody gets them. The side effects are either from the medicine itself or from the injection procedure. Most of the side-effects involve the eye alone.
Common side-effects include discomfort during and after injection, bruising of the white of the eye, an increase in the eye pressure and moving black dots in your vision.
Less common side-effects of any injection treatment include inflammation in the eye, bleeding, infection, retinal tear, detached retina and cataract.
Regardless of which injected drug is used, each injection procedure carries a very small risk (1:1000) 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).
All of these side-effects may occur with each of the available anti-VEGF medicines.
Inflammation and an immune response (“immunogenicity”) Inflammation is a rare complication but appears to be more with longer acting drugs or when one type of drug is switched to another type. Rarely this inflammation can be serious and sight threatening. The risk of this complication is very small (less than 1 in 1,000 risk).
Iluvien and Ozurdex (steroid based drugs) have an associated risk of cataract (85%), although this can be treated by cataract surgery and glaucoma (high pressure in the eyeball) in less than 1 in 3 patients of patients which may require eye drop treatment or rarely a glaucoma operation. Your doctor would decide if you were suitable for this treatment and would discuss the risks and benefits of the treatment with you.
There are no proven risks to your general health with these injection treatments.
Intravitreal injections of any of the drugs injected into the eyeball to treat DMO have not been studied with regard to safety during pregnancy or breast-feeding. Patients who were pregnant / breast-feeding were excluded from research studies examining the safety of any of the drugs now licensed for injection into the eye. Female patients receiving these drugs who are pre-menopausal or who are within 1 year of menopause should therefore use adequate contraception and should not breast feed.
How do I prepare for the Diabetic Macular Oedema 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/ outpatient 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 waiting area in the Eye Clinic.
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 OCT scan if you are having injection treatment.
The eye will be numbed with local anaesthetic drops at the time of the injection procedure.
What happens afterwards?
Your vision will be slightly blurred for a few hours after the injection until the dilating drops have worn off. Your eye may feel slightly irritated/ watery after the injection and may be slightly blood shot. This is normal.
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 Tel: 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.
