Clinical Services: Avastin Intravitreal Injections
What is Avastin?
Avastin is an antibody that inhibits the growth of new blood vessels. It blocks the transmitter called VEGF (Vascular Endothelial Growth Factor), which is involved in growth and development of blood vessels. In the eye, Avastin has been found to be useful in treating conditions where VEGF is thought to be involved. These conditions often involve leaking or bleeding blood vessels in the retina. By blocking the action of VEGF, leakage and swelling in the retina can be reduced and even shut down. It is used in the treatment of diabetic retinopathy, retinal vein occlusions, macular degeneration, and cystoid macular oedema. It is given in the form of an intravitreal injection.
Avastin was originally developed for use in the treatment of bowel cancer, and has now been shown to have beneficial results relating to the eye.
How is the injection performed?
The injection will be performed in our Day Surgery unit under sterile conditions. You will be dressed in theatre attire and assisted to sit on the theatre chair. The assisting nurse will administer four anaesthetic drops to the eye over a 20 minute period. Whilst administering the drops, the nurse will instruct you to look in a certain direction. Between doses of the drops you must keep your eye closed to maximise the anaesthetic effects.
After 20 minutes, your ophthalmologist will perform the injection. The outside of your eye will first be cleaned with an antiseptic solution. You will be instructed to look in the same direction you were asked to look whilst receiving your anaesthetic drops. A small needle is inserted through the white part of your eye and the Avastin is injected into the vitreous (the jelly inside the eye). You may experience a sensation of pressure but the injection should not be painful.
Are there any side effects?
Some patients experience a stinging sensation after the injection. This is due to the antiseptic solution and should subside quite quickly. Please inform the nurse if you do experience pain so it can be monitored and documented. Most patients do not experience any other pain following the injection.
What are the risks?
Your ophthalmologist will explain the risks involved with the Avastin injection prior to the procedure. Infection, haemorrhage and retinal detachment may occur in less than 1% of patients who have an injection into their eye.
Giving 300 times the dose of Avastin we use in the eye and giving it intravenously in patients with cancer being treated with other toxic agents, the following side effects have been noted:
- Doubling of the risk of heart attack and strokes
- 2% gastrointestinal perforation
- Hypertension and proteinuria
- Nose bleeds and poor wound healing
It is possible these systemic side effects could occur in patients being treated with intravitreal Avastin, but common sense would tell us that it is much less likely to occur if we inject a very small amount into the eyeball, as opposed to giving a large dose intravenously.
It has to be emphasised that this drug has not been subjected to a controlled trial and we have no long term data as to its beneficial or adverse effect. Reports to date suggest that it has been effective in preserving vision and in some patients improving it. It appears to be relatively safe.
Although rare, you must be aware of the following symptoms which may indicate a complication:
- Severe Pain: This could indicate a rise in intraocular pressure or an infection.
- Discharge: A discharge from the eye could indicate an infection. The eye may also appear red and swollen or you may feel a burning sensation or itchiness in the eye.
- Loss of vision: If your vision suddenly deteriorates or you notice a black shadow/curtain progressing over your visual field, it could indicate a retinal detachment or further progression of your macular condition. Remember though, it is normal to see a black "blob" immediately after the injection, which will break up over the following week.
If you experience any of the symptoms listed, or have any other concerns, please contact us.
You will be given a prescription for antibiotic eye drops which must be administered four times a day for one week.
Most patients do not experience any pain other than a slight stinging sensation immediately following the injection. If your eye feels slightly tender or you experience a mild headache you may take a dose of paracetamol. You should not require any stronger pain relief.
You will have a post procedure check up with your ophthalmologist one month after the procedure.