What is Anti-VEGF?
Is a new family of drugs, designed to stop the growth and leakage of these unusual blood vessels that develop in Wet AMD. It does so by neutralising “VEGF” the very substance that promotes these vessel growth. The net result is stopping the very damaging effect of the leakage of fluid in the macula.
It is administered by injecting it directly into the affected eye under local anaesthetic. The procedure is relatively simple and is pain free. It takes about 10-15 minutes to administer.
This is a new concept of treatment and is still evolving. The information given below is based on the up to date data available.
What Anti-VEGF drugs are available?
At the moment, there are three Anti-VEGF drugs available, Macugen (Pegaptanib Sodium), Avastin (Bevacizumab) and Lucentis (Ranibizumab).
Macugen (Pegaptanib Sodium)
Works by blocking only a selective type of VEGF. It is the only drug approved so far in USA and Europe. It is given at 6 weekly intervals. Studies so far recommend using the drug for at least a year which means approximately 9 injections in the first year. The success rate using this treatment as depicted from major research trials in the USA (VISION Trials) show that about 70% of patients stabilise vision (less than 15 letters decline in vision using special acuity ETDRS chart), while those who did not have this treatment showed 55% stabilisation of vision.
Work by blocking all forms of VEGF. Produced by the same company as Avastin (Genentec, USA) is a very similar drug but formulated for the eye. It has only just been approved in the USA and due for approval in Europe early 2007. There are many studies that looked at administering this drug at different intervals. From these studies, it is now recommend using the drug every month for the first 3 months and then a top up as required depending on the response. The results are very encouraging and show up to 96% of patients stabilise vision compared to up to 64% in those that did not receive any treatment. Moreover, those who received the treatment show up to 40% chance of improving vision after treatment.
Is a drug similar to Lucentis (Ranibizumab) and is produced by the same company (Genentec. USA). Originally developed to treat Cancer of the Colon. However trials using this drug to treat AMD in the eye have shown it to be as effective as Lucentis. However, such trials using Avastin are only small studies and are not controlled trials. So far these studies showed that up to 96% of patients stabilise vision with Avastin. Also, up to 38% of these patients improve vision after treatment. This drug as it is designed for Colonic Cancer will not be approved for eye use and therefore its use in the eye is considered “Off-lable”. This is by no means the only drug used in eye treatment that is off-lable. Also, it has been shown to be non-toxic to the retina in animals.
What are the side effects?
These side effects can be related to the actual procedure of administering the drug or the drug itself.
The possible risks include infection, inflammation, retinal tears, retinal detachment, haemorrhage inside the eye and damage to the lens of the eye. Collectively these risks are less than 8%.
There are also theoretical potential systemic side effects to include raised blood pressure, bleeding tendencies, heart attacks and strokes. However, studies have so far shown that these drugs given inside the eye does not increase the incidence to more than it is at people at this age which is about 2%.
“No matter how intelligent a man is, he can’t see what he doesn’t know how to see.” Ursula K. Le Guin