Bright Sight

Oliver Backhouse, Consultant Eye Surgeon www.cataract.org.uk

Injection therapies for Macular Degeneration (AMD)
Lucentis and Avastin for ‘Wet’ AMD

The number of people in the world with AMD is increasing. In the UK it affects around 3% of people aged 75 and older. A combination of environmental factors and genetic factors are thought to play a role with smoking being the most consistently identified environmental risk factor. A healthy diet can play a role in reducing the risk of AMD progression.

To help diagnose AMD and plan appropriate treatment, fluorescein angiography is undertaken. Fluorescein is a non-toxic vegetable dye that is injected into a vein in the arm followed by lots of rapid photographs of the dye at the back of the eye as it passes through the arteries and veins. Fluorescein angiography was important in the 1980s and 90s to identify the areas of leaking retina that needed laser treatment. Prognosis after this laser treatment was poor with 50-70% of treated eyes developing a recurrence of the wet AMD over a two year period. Most eyes experienced moderate or severe visual loss. Photodynamic therapy was the next major advance but many eyes with wet AMD were not suitable for treatment and, on average, it only slowed the progression of visual loss rather than provide any visual gain.

Lucentis (ranibizumab), Avastin (bevacizumab) and Macugen (pegaptanib) are medicines that inhibit VEGF (vascular endothelial growth factor). VEGF has a central role in wet AMD as it makes the blood vessels leak which inturn gives rise to the symptoms of distortion and loss of vision seen in the early stages of wet AMD. Trials on Lucentis have shown it to keep eyesight within 3 lines of the initial presenting vision in 90% of patients with approximately 30% actually gaining 3 lines of vision. Similar results are found with Avastin but this is currently not licensed for use in AMD although trials are ongoing comparing it to Lucentis. Macugen appears not to work as well but has a probable role in those patients who do not respond to Lucentis.

These medications are given directly into the eye on an out-patient basis in a sterile environment. Initially 3 injections are given on a monthly basis. How frequently they are given after is open to debate but it would appear that the best results are got from a monthly review with a repeat injection being given if there is evidence of a drop in vision of greater than 5 letters or a return of the fluid at the macular as detected by an OCT scan. The interval between two doses should not be shorter than one month.

Most side-effects are due to the injection itself with infection, bleeding, traumatic cataract or a detached retina being rare. VEGF is essential for proper blood vessel development and there is concern that some anti-VEGF medication is absorbed systemically giving rise to a possible small increase in the susceptibility to stroke. Most clinicians feel that the benefit of treating the AMD outweighs the small potential risk of stroke.

Government guidelines regarding who can get this treatment on the NHS is continually being reviewed and updated. Although expensive and inconvenient, injection of anti-VEGF medication into the eye represents a major step forward in the treatment of wet AMD.