What is the Macula?
The retina functions like a layer of photographic film lining the back of your eye. It contains specialised cells that are needed for sight. The very important central area of the retina that lets you see colours and details is called the macula.
What is Wet Age-Related Macular Degeneration (AMD)?
Wet Age-Related Macular Degeneration occurs when an abnormal network of blood vessel sprouts underneath the macula.
This abnormal network of blood vessels causes destruction to the macula by leaking blood, fluid and lipid into the macula. Because we rely on the macula for important visual tasks, Wet AMD typically causes rapid deterioration in our ability to read, recognise colours and see details.
If left untreated, the central vision is typically lost over a period of 3 to 6 months.
Who is affected by Wet AMD?
The main risk factor is advancing age. In addition, smoking, poor nutrition, a strong family history and excessive exposure to sunlight have all been identified as risk factors for the development of wet AMD.
What are the symptoms of Wet AMD?
Wet AMD causes distortion and blurring of the central vision and this usually results in difficulty with detailed visual tasks such as reading, watching television, driving and recognising faces. Once established, wet AMD can progress quickly.
How is Wet AMD diagnosed?
The diagnosis of Wet AMD is made by a combination of clinical examination Dilated Fundoscopy and Optical Coherence Tomography (OCT) in most cases. The OCT is an entirely non-invasive laser scanning test that produces a detailed cross-section picture of the macula. OCT can look at the extent of the swelling in the macula caused by the abnormal network of blood vessel in Wet AMD. OCT also allow us to monitor the effect of the treatment at subsequent visits.
Occasionally, Fluorescein Angiography is performed to confirm the diagnosis of Wet AMD. Fluorescein Angiography is a more invasive photographic-dye test. It is performed by injecting a dye (Fluorescein) into a vein in the arm to photograph the abnormal network of blood.
What treatment is available?
The abnormal network of blood vessels, once formed, is dependent on a signalling molecule, the Vascular Endothelial Growth Factor (VEGF), to keep growing and leaking.
Anti-VEGF agents are engineered humanized antibody against VEGF. They work by blocking the effect of VEGF on the abnormal network of blood vessels in wet AMD, causing the abnormal network of blood vessels to stop leaking and growing and thereby arresting the progression of wet AMD.
Treatment for Wet AMD therefore requires Intravitreal Therapy (IVT) of repeated injections of Anti-VEGF agents into the vitreous cavity, the main eye cavity at the back of the eye, to ‘dry up’ the macula in Wet AMD.
What Anti-VEGF agents are available?
There are currently three Anti-VEGF agents which are effective and routinely used in the treatment for Wet AMD.
- Bevacizumab (Avastin)
- Ranibizumab (Lucentis)
- Aflibercept (Eylea)
The choice depends on the nature of your wet AMD and other funding/economic considerations. Your surgeon will discuss the choice of Anti-VEGF agents with you in details.
What are the aims of treatment?
Intravitreal Therapy (IVT) with Anti-VEGF agents is able to stops further deterioration of the central vision in the majority of patients (95%) with Wet AMD. Furthermore, a small proportion of patients (20-30%) can experience major improvements in their vision.
However, the main aim of the treatment is to stop the decline in vision. It can be difficult to accurately predict whose vision will improve with treatment on an individual patient basis, but the vision is very likely to stabilise in the vast majority of patients.
To maintain the effects of treatment with Anti-VEGF agents, you will need to have regular check-up visits, with repeated IVT treatment with Anti-VEGF agents from your surgeon.