What is an intravitreal injection?
The injection of a small volume of advanced drugs into eyes is now the best way to treat many retinal conditions. This way of giving medication is known as an ‘intravitreal injection’.
How is an intravitreal injection given?
Intravitreal injections are carried out in the clinic under aseptic conditions to minimise the chance of infection. Before receiving an intravitreal injection, eye drops are administered to numb the eye. Once your doctor is satisfied that the eye is numb, they will apply an antiseptic solution to the surface of the eye and then inject a small amount of drug through the wall of the eye. Some patients notice black spots in their vision after the drug has been injected and it is not uncommon for the eye to be a little red around the injection site. If this occurs the redness will settle after a few days. The injection is not normally painful.
What Are the Risks Involved?
Most retinal conditions for which intravitreal injections are used will improve with treatment. Unfortunately, the nature of eye problems means that some peoples vision may not recover even if the intravitreal drugs result in improvement of the retinal structure and not all problems will respond to the injections. There is also is a very small risk that the injections themselves may cause problems. Any of these may cause decreased vision and additional procedures may be needed to treat these complications. The principal risks are;
- Infection in the eye (Endophthalmitis) – there is approximately a 1 in 2500 risk of serious infection in the eye following an injection of any kind. For this reason, every precaution is taken to avoid introducing bacteria into the eye, with scrupulous attention to sterile technique. It does, however, remain potentially the most serious complication associated with any injection into the eye and, if they occur, infections often cause permanent loss of vision.
- Bleeding inside the eye (Vitreous haemorrhage) can occur after an intravitreal injection. If this occurs the vision may be temporally reduced but in most cases the blood will clear spontaneously within a few weeks.
- Post injection pain. Very occasionally patients can have a reaction to the solution that is used to prepare the eye for the intravitreal injection. In most cases the eye is simply a bit gritty for 24 hours but in extreme cases it can be very painful for up to 12 hours. If this occurs your doctor will be able to use a different preparation for any subsequent injections that you may need.
- Retinal Detachment. There is a small incidence of retinal detachment after intravitreal injections (approximately 1:7000). Most retinal detachments can be repaired surgically, but a proportion of people do lose vision after such problems.