- Injections for Macular Degeneration
- How do I know if I've got "wet" ARMD?
- How are the injections given?
Injections for Macular Degeneration
For certain patients with wet ARMD, treatment is available that can prevent further visual loss and in certain circumstances, may even produce an improvement in visual acuity. These treatments are called "Anti-VEGF" therapy.
In wet ARMD, a chemical is produced by the retina called VEGF (Vascular endothelial Growth Factor). This chemical has properties that promote the development of "new vessels" under the retina. These new vessels occur right under the centre of the retina and can damage the overlying retina and because this process occurs at the centre of the vision, it has a profound effect on sight. The blood vessels may leak fluid into the normally dry retina, or they may even bleed causing scarring at the centre. These events can profoundly effect the vision.
In order to counteract the effect of VEGF in ARMD, pharmaceutical scientists have developed treatments known as "Anti-VEGF" injections. Three currently available treatments have been developed: Macugen®, Lucentis® and Avastin.
This was the first anti-VEGF therapy specifically developed for ARMD, and obtained FDA (USA) approval in December 2004.
This was developed later for wet ARMD, and has been shown to be very effective in clinical trials. Because of the effectiveness of Lucentis therapy, it has largely superceded Macugen in the treatment of wet ARMD.
Avastin was originally an anti-VEGF drug used for the treatment of colon-rectal cancer and was administered systemically. However, over the past few years, there is increasing evidence that injection treatment of Avastin into the eye for ARMD is as effective as Lucentis therapy. There are currently ongoing trials that are directly comparing Lucentis therapy with Avastin, and their results should be known soon.
How do I know if I've got "wet" ARMD?
How are the injections given?If you develop symptoms of distortion of your central vision, and/or loss of your central vision, then you should be seen by an ophthalmoloogist who specialises in diseases of the retina. The specialist on examining your eye will tell you whether you have any features that suggest you may have "wet" macular degeneration. If so, he/she may accordingly organise for you to have some investigations (known as Optical Coherence Tomography (OCT) and fundus fluorescin angiography (FFA)).
Optical Coherence Tomography:
OCT is an invetsigation that involves taking a very high resolution optical scan of the retina. It is completely painless and non-invasive, and takes approximately 1-2 minutes to perform. OCT produces such high resolution images that it has revolutionised management of retinal diseases in recent years.
Fundus Fluorescein Angiography:
FFA is an investigation where a dye (fluorescein) is injected into a vein in the arm, and as it travels into the small blood vessels of the eye, the eye is photographed using a special filter that shows the dye in the blood vessels. Though this is an invasive test, it gives important information to your ophthalmologist about the nature of your macular degeneration, whether it is dry or wet, and if wet, whether its amenable to treatment.
How are the injections given?
If your ophthalmologist has determined that you have "wet" ARMD amenable to treatment, he/she will discuss with you the potential use of anti-VEGF therapy injections. Anti-VEGF treatment are given as an injection into the central cavity of the eye (called the vitreous) and because of this, they should only be administered by/ under the supervison of an expert in retinal disease. Becasue it is an invasive treatment, the procedure is done in a sterile room with proper sterile preparation of the eye, such as draping and sterilising of surrounding tissue with iodine. The actual injection only needs topical (i.e. drops) anaesthesia and usually only takes less than 1 minute. Afterwards, you will be given some topical antibiotic drops to use (normally for 5-7 days) and told to report any changes in vision.
Whilst anti-VEGF injections have transformed the treatment of this visually-debilitating disease, there are some drawbacks to treatment.
The current anti-VEGF therapies are short-acting and their effect wears off within 4-6 weeks. Therefore, all patients diagnosed with "wet" ARMD requiring treatment need as a minimum three injections (separated approximately 1 month apart), and after that, repeated OCT scanning is performed as some patients will continue to need further further monthly injections. Indeed there are a few patients that need repeated injections for up to two years and beyond (though these are a minority). Further, anti-VEGF therapy does not work for everyone, and some patients do not respond at all to the treatment, and eventually continue to lose central vision in the effected eye.