How can anti-VEGF injections treat wet AMD?
Age-related macular degeneration (AMD) involves damage to the part of the eye called the macula, which is responsible for making sure we see the fine detail of things in front of us (central vision) clearly.
This means that a person with AMD may have trouble reading a book or seeing things clearly from a distance. However, side (peripheral) vision usually remains normal. Here, we take a look at treatment options for AMD, specifically what anti-VEGF injections are and how they treat the wet form of macular degeneration.
What is VEGF?
VEGF (vascular endothelial growth factor) is a protein produced by cells when there is not enough oxygen or blood flow to an area. It causes blood vessels to leak blood and fluid and can stimulate the growth of new blood vessels in that area. A primary characteristic of wet AMD is when this happens in the choroid, a layer of blood vessels underneath the retina at the back of the eye.
In some cases, this can lead to a rapid loss of central vision, which can affect your ability to perform daily tasks such as reading, watching television, or recognising faces. Wet AMD causes distortion of vision that makes straight lines look wavy, as well as blind spots, and a general sudden loss of central vision.
Anti-VEGF treatments are a group of medicines which reduce growth of these new blood vessels along with any swelling and leakage. Treatment is given as an injection into the white of your eye.
What happens during anti-VEGF treatment?
Your ophthalmologist may perform tests such as a slit lamp examination, fluorescein angiography, or optical coherence tomography (OCT) to assess the extent of your AMD and decide whether treatment with anti-VEGF injections is the right option for you.
Anti-VEGF treatment usually has to be started quickly, before the new blood vessels or swelling do too much damage to the macula. Usually, you will start by having a course of three injections, once every four weeks for three months.
How are anti-VEGF treatments injected?
The drug is injected directly into the vitreous, which is the ‘jelly’ that fills your eye, using a fine needle. This shouldn’t cause much discomfort, and is very similar to having blood taken from your arm. The entire procedure takes fifteen to twenty minutes, but the injection itself is over in less than ten seconds.
What happens before an anti-VEGF injection?
Before the injection, you’ll be given anaesthetic eye drops, the area around your eyes will be covered with a drape, and a small clip will be used to keep the eye open and prevent you from blinking. The injection site will be marked, and a few seconds later, the injection will be given.
You can’t see the injection being delivered as it is given in the side of your eye, away from your direct line of sight. Because of the numbing effect the anaesthetic has on your eye, the injection will feel like a small point of pressure on your eye rather than a scratch.
Drops of sterile water will be administered after the injection to reduce any irritation in the eye. The procedure is generally straightforward, quick, and usually painless, but your eye may feel a little sore after the anaesthetic wears off.
What are the after effects of an anti-VEGF injection?
Since the pupils are dilated before the injection, your vision may be blurry for a while afterwards. However, this should improve by the next day. Apart from a slight ache or discomfort in the eye for a day or two, some patients may find that the white of their eye has turned red at the injection site or notice floaters in their vision (small spots or strings), but these usually disappear over the course of a week.
You can usually resume your everyday activities straight away after an anti-VEGF injection, however, it’s important that you avoid rubbing your eyes and getting water into them for the first few days following your injection.
Complications from anti-VEGF injections
The risk of complications from anti-VEGF injections is very small and comes from having an injection, rather than the anti-VEGF drug itself. For most people, the benefit of having the treatment to protect their sight outweighs the very small risk that comes with the injection. Possible complications from anti-VEGF injections may include1:
- Endophthalmitis — Although the risk of endophthalmitis (inflammation of fluids inside the eye) is minimal, infection might occur in some patients, with symptoms such as painful and red eye, sensitivity to light, and blurred vision. If you develop these symptoms in the days following your injection, you need to be checked immediately by your ophthalmologist.
- Increase in intraocular pressure (IOP) — Intraocular pressure is the fluid pressure inside the eye, and it can rise or fall depending on a number of features, like the drainage of the fluid (aqueous humour). This risk of raised IOP is more prevalent in glaucoma patients. For most people, an increase in IOP is temporary and usually resolves on its own within a few days.
- Retinal detachment — In rare cases, symptoms such as floaters, flashes of light in vision, and a curtain effect or shadow coming across your field of vision might indicate that the retina has detached from its position at the back of the eye. A retinal detachment can be treated with surgery, but this needs to be done urgently to prevent sight loss in that eye.
- Cataract — A cataract is a clouding of the lens inside the eye which can cause vision to become cloudy or misty. A cataract can be treated with surgery, by removing the cloudy lens and replacing it with a clear, artificial lens.
- Blood clots, bleeding, or inflammation inside the eye.
Will there be any follow-up treatment?
Depending on how your condition is responding to treatment, your doctor may prescribe certain tests to check how well your anti-VEGF treatment has worked, alongside a check-up with an eye chart. These tests will check for new blood vessel growth and any swelling in your macula, and will help your ophthalmologist to identify whether there is any active leakage of blood and fluid at the back of your eye. If there is, you will likely need more anti-VEGF injections.
You will usually receive an anti-VEGF injection once a month, or every two months, until the bleeding and swelling is brought under control and your sight stabilises. How often you get injections and how long your course of treatment will vary from patient to patient.
How effective are anti-VEGF treatments?
Anti-VEGF treatment has a very high success rate for people with wet AMD, and has been shown to prevent sight from worsening in over 90% of patients. Up to 40% of patients may also see an improvement in their vision, which enables them to read up to three extra lines on the letter chart used in eye exams.2
There are other options available for the small number of patients with wet AMD who don’t respond to anti-VEGF treatment, including combination therapy (where more than one medication is used at one time), transpupillary thermotherapy (where part of the eye receives near-infrared or infrared light exposure), surgical excision of choroidal neovascularisation (CNV) (where the CNV is removed), and use of non-steroidal anti-inflammatory drops (NSAIDs).3
Being diagnosed with an eye condition like wet AMD can feel overwhelming, but there are a number of adjustments you can make to adapt to any changes in vision you’ve experienced. For example, you might increase the font size of text, make web pages or images bigger, use brighter lighting, or use colour to make things easier to see. In addition, you can also ask your ophthalmologist, optometrist, or GP about various low vision aids available to help you manage your wet AMD.
1. Falavarjani, K Ghasemi, and Q D Nguyen. “Adverse events and complications
associated with intravitreal injection of
anti-VEGF agents: a review of literature.” Eye (London, England) vol. 27,7 (2013):
2. Park, Y. G., Rhu, H. W., Kang, S., & Roh, Y. J. (2012). New Approach of Anti-VEGF Agents for Age-Related Macular Degeneration. Journal of Ophthalmology, 2012, 1–7. doi:10.1155/2012/637316