Wet Age-Related Macular Degeneration, or wet AMD for short, is a disease characterised by abnormal blood vessels that leak and bleed in the central part of the retina called the macula. The macula is responsible for sharp vision. The remaining retina, outside the centre, is not affected and continues to provide enough vision for orientation and getting about. The abnormal blood vessels growing under the macula are referred to as choroidal neovascularisation or CNV for short.

What is likely to happen if the abnormal leaky blood vessels are left alone? If left untreated the abnormal leaky blood vessels may bleed at the macula and cause swelling of the retina for long periods. In this situation the vision becomes more blurred and distorted in the centre. Long periods of retinal swelling or bleeding at the macula may produce loss of retinal tissue and scarring, causing permanent damage and non recoverable loss of vision. Although some patients do relatively well and do not lose too much vision usually wet AMD causes significant visual disability in 1-2 years from onset. Affected patients find reading difficult and struggle to recognise faces. In severe cases they may not be able to recognise the food in their plate as a result of the loss of vision from wet AMD.

Does wet AMD cause complete blindness? Wet AMD does not cause total blindness. Only the central, sharp vision is lost. The surrounding vision, useful for orientation and getting about, is not lost.

Is there more than one type of wet AMD? There are various types wet AMD identified according to how the abnormal blood vessels (the CNV) leak when investigated with a special test called fluorescein angiography. The type of wet AMD called Predominantly Classic CNV is more aggressive, with rapid progression and poor prognosis but also better response to treatments. The type of wet AMD referred to as Minimally Classic or Occult CNV tend to have slower progression, and less predictable prognosis and response to treatment. Knowing these terms can be helpful when making searches on the Internet or reading more about wet AMD.

Is there a cure for wet AMD? Unfortunately there is not really a cure for wet AMD. However there are treatments that can slow down the disease or stop it before it causes too much damage. Treatments are getting better and better as we advance with research and understand more about this difficult disease. 

Does any case of wet AMD require treatment? Not all wet AMD needs to be treated and to undergo the risks associated to treatment. There are cases of less aggressive wet AMD with relatively good vision that need only adequate monitoring. Cases of wet AMD that have progressed to advanced scarring or loss of vision usually would not benefit from treatment.

How long for should I expect to be reviewed or treated if my wet AMD requires treatment? Treating wet AMD often implies long term commitment, with numerous follow ups and repeated treatments. This is important to understand for best results. A “quick fix” approach is not realistic with wet AMD, it is seldom helpful and may even be counterproductive as it leads to underestimation or denial of the disease until it is too late. Follow up and treatment cycles often carry on beyond two years.

So, what are the main treatments of wet AMD?

The standard NHS treatment for wet AMD is Photodynamic Therapy (PDT). PDT is restricted to “Predominantly Classic CNV”, which represents approximately 40% of eyes with wet AMD. This means that the majority of patients attending a wet AMD clinic are not eligible to PDT.

Treatment with PDT is designed to shut down the abnormal blood vessels that leak and bleed at the macula. PDT consists of a drug infused in a vein of your arm and a brief exposure to a laser beam to activate the drug into your eye. PDT is repeated approximately 4-5 times over 2 years as the abnormal blood vessels reopen. Review every 3 months is typically arranged to assess the need to re-treatment with PDT. Repetition of PDT eventually quietens the wet AMD but unfortunately this may happen with scarring and loss of retinal tissue, both of which may be associated with disappointing loss of vision.

Is there any treatment newer than PDT?

There are new treatments for wet AMD that you may have heard about on TV or in the press. They are based on direct injections of drugs into the eye. More precisely, drugs are injected into the vitreous, which is the jelly that fills the eye ball. The procedure is called intravitreal injection. The new treatments work differently from PDT. The new drugs counteract directly the chemicals that cause the abnormal blood vessels to leak and bleed at the macula, keeping them quiet and reducing the amount of scarring as healing slowly occurs. 

Improvement of vision without the new treatments is uncommon.

Macugen was licensed for wet AMD in May 2006. It is injected in the eye every 6 weeks and overall it appears to be only slightly superior to PDT. It has limited benefit and scope when compared to more recent drugs like Lucentis and Avastin. However, it may be a reasonable choice when wet AMD is diagnosed very early. In these cases it can be used with the idea of switching over if it does not work.

Lucentis was licensed in the UK in January 2007. It is licensed to treat wet AMD with repeated injections into the eye. In two large studies Lucentis stabilised vision in over 90% of eyes with wet AMD and improved vision in 30-40% (depending on the particular subtype of disease). The treatment consisted of 4 weekly intravitreal injections over 2 years. Lucentis gives greater chances to improve vision than PDT. For instance, less than 6% of eyes with wet AMD eligible to PDT improved their visual acuity when treated with PDT alone as opposed to 40% of eyes treated with 4 weekly injections of Lucentis. 

Avastin is a drug similar to Lucentis but it is not licensed for injections into the eye. It appears to have similar benefit to vision than Lucentis. Although deemed safe at the doses used in the eye, its safety profile is not well studied. It is injected 4-6 weekly and being not easy to get hold of must be ordered with at least one week notice. Its main advantage is reduced cost. Before considering Avastin it is important to ask for written information on risk and benefits such as a dedicated consent form that you may be expected to sign.

Risk of injections into the eye. Please bear in mind that every injection carries small risks of infection, and very rarely of retinal detachment or bleeding into the eye regardless of the drug being injected into the eye. The most feared complication of an intravitreal injection is endophthalmitis, a severe infection inside the eye ball that comes with pain and may cause considerable loss of vision. The risk of endophthalmitis per single injection is approximately 1:1,500 that is slightly less than cataract surgery.  Approximately 1% of patients who received a total of 25 intravitreal injections over a period of 24 months experienced endophthalmitis.

Can the number of intravitreal injections be reduced?
Strategies are being studied to reduce the number of reinjections without compromising the favourable visual results. It is likely that the majority of patients will require considerably fewer injections than the 4 weekly protocols applied in clinical trials. Combining PDT and intravitreal injections appears to be promising in reducing the need of reinjections. This is desirable to reduce total cost and risk of complications, especially infections.

What should I do if I want to consider new treatments for wet AMD?

Please note that this information is intended solely to assist you in deciding whether to pursue the new treatments for wet AMD that are not available in the NHS. If you decide to pursue any new treatment for wet AMD it is entirely up to you to choose the macular specialist who will deliver it for you and take care of your wet AMD. Your GP may advise you. I am happy to arrange a referral to another macular specialist if you wish to have a second opinion. However, if several weeks have past from your visit to my clinic it is appropriate to have a follow up visit to obtain the most up to date information about your wet AMD. 

COMPARISON OF NATURAL HISTORY (NO TREATMENT)

AND DIFFERENT TREATMENTS FOR WET AMD