Injections for macular degeneration, diabetic retinopathy and other conditions
The treatment of several diseases of the retina involves injecting drugs into the central cavity of the eye (the vitreous cavity). These injections have become very popular given their effectiveness. There are several drugs commonly used for injections, including corticosteroid medications and, more commonly, anti-VEGF medications.
Corticosteroids are derivatives of cortisone and have a beneficial effect on diabetic retinal problems (diabetic retinopathy with macular oedema) and on inflammatory eye diseases (uveitis, with or without macular oedema).
Anti-VEGF medications are mainly used in "wet" macular degeneration, diabetic retinopathy and retinal vein occlusions. There are three main medications used: Avastin (Bevacizumab), Eylea (Aflibercept) and Lucentis (Ranibizumab). They all have very similar effects and side effects, although individual patients may have a better response to a specific drug than to another.
What is the purpose of the injections?
The purpose is usually to achieve improvement in the state of the retina, resolution of swelling of the macula or regression of bleeding-prone blood vessels. Due to the limited duration of effect, the injections often have to be repeated, although the number of injections and duration of treatment vary among different patients. Some patients require a single injection every several months or years, and others need frequent injections every one to three months in order to maintain the effect of treatment. Using an analogy, the action of drugs injected into the eye in those conditions may be compared to the action of weed killers on weeds: They have a rapid effect in destroying the "bad growth" (weeds in the garden, harmful blood vessels in an eye with macular degeneration), but need to be re-used after a while, when their effect wears off, and new growth of harmful blood vessels occurs. Even with successful treatment, there are often visual problems which may not be fully reversible, but treated patients do significantly better than untreated patients.
How are the injections given?
Most injections are given in clinics, not in operating theatres. They are done under sterile conditions, and local anaesthesia is used to minimise pain. They may be painless or cause slight, brief pain. The whole process of receiving an injection usually lasts less than 5 minutes, and return to most normal activities is expected within minutes to a few hours. In general, there are no restrictions after receiving an injection, and no special medications or eye drops are required.
What are the after effects of eye injections?
Positive effects: In most cases there is a beneficial effect on the vision, improving it or stopping it deteriorating. This may be evident by improving vision, as well as by improving anatomical signs in the examination of the eye and in the macular scans (OCT).
Common negative effects: There is often minor discomfort in the eye for a day or two after the procedure, and a superficial haemorrhage ("bloodshot eye") which may be noticeable to others. These do not have any significance for the health of the eye or the vision. Floaters or little black circles in the vision may be noticeable to the patient for a day or two.
What are the risks of the injections?
Rarely, significant complications may arise from any injections into the eye. Problems such as retinal detachment, infections within the eye (endophthalmitis) may require urgent treatment and/or surgery if they occur. Injections of corticosteroids have are likely to induce glaucoma or a cataract. There is no conclusive evidence that injections of anti-VEGF medications into the eye has adverse effects on the general health of the patient (systemic effect), although there have been theoretical concerns that these medications may increase the risk of strokes and cardiac events. These concerns have not been proven by several large studies looking into this question.