Understanding injection therapy for eye conditions

Eye injections are a common and very effective form of treatment for conditions affecting the macula or the retina. They help to improve and preserve vision by reducing leakage or bleeding from damaged or abnormal blood vessels.

Injections are given to treat wet macular degeneration, diabetic macular oedema, retinal vein occlusions, uveitis or inflammatory eye disorders, myopic macular degeneration, and less common disorders such as retinal macroaneurysms and choroidal neovascularization from causes other than macular degeneration.

The retina is the light sensitive tissue that lines the back of the eye, much like the film in a camera. The central part of the retina is called the macula. Light focused on the macula gives us fine central vision for reading and detail recognition.

Eye injections can be administered via various routes:

• An intravitreal injection is the injection of a medication into the vitreous cavity. It is the most commonly used method of injection. Various medications may be injected into the vitreous cavity, these include anti-vascular endothelial growth factor (anti-VEGF) medications, corticosteroids, and steroid implants.

• An orbital floor injection is the injection of a medication along the outside of the wall of the eye, but does not penetrate the eye. Corticosteroids are often administered this way for macular oedema due to inflammation.

Intravitreal injections are performed in an outpatient clinic setting under sterile conditions. Every effort is made to ensure that the procedure is comfortable. Prior to the injection, anaesthetic drops and local anaesthetic are used to numb the eye, and topical antiseptic solution is used to clean the eye. The injection is given through the white part of the eye (sclera) at a specific location where it is safe for injections to be performed.

After the injection, there can be localised redness at the site of the injection from superficial bleeding under the conjunctiva (outer clear lining that covers the white of the eye). If this happens, the eye may appear red. This is known as a subconjunctival haemorrhage – this is not a serious issue and will resolve by itself. The eye may feel gritty and watery for up to 24 hours. You may experience a few floaters in your vision, which also typically resolve within a day. Lubricating eye drops can be used to ease any irritation after the injection.

One potential complication of an intraocular injection is the development of an infection inside the eye. Fortunately, the risk of this complication is low (less than 1 in 3000 injections). The symptoms of infection are often apparent within the first few days after the procedure. If you have severe pain or vision loss after an injection, you should see your doctor immediately.