The standard textbooks define wet AMD as a neovascular disease. The poor response of wet AMD towards macugen therapy (anti-VEGF against VEGF A 165, a selective antivascular form of VEGF) arises the question whether wet AMD is predominantely a neovascular disease or more than that an exsudative disease. What do you think?
In my opinion wet AMD, recently named as an exudative type of AMD is a combination of exudation and neovascularisation. Regarding poor response on intravitreal anti-VEGF therapy ,particulary on first approved for ophthalmology use Macugen, its short duration of action , tachyphylaxis after repeated injections and also I suppose that not only VEGF plays a cardinal role into pathogenesis of wet AMD.
Just to be on the same page - what do you mean by exudation? What is your definition?
Dear Heinrich
to the best of my knowledge this is the most current classification system agreed by a committee of AMD expert: PMID 23332590 You can refer to that paper for the terminology which derives from the pathogenese understanding.
There are several new study approaches to inhibit other driving growth factors within the subfamily of VEGF in nAMD. And I think our understanding of the molecular nature and habit of known VEGFs is limited so that we cannot fully explain how the four commonly used Anti_VEGF substances work.
In my opinion the main factor is the appearance of new vessels underneath the retina caused by some risk factors mainly ischemia. These new vessels are unable to keep the blood-retina barrier, and therefore a "leakeage" is produced
Thus in my opinion the right term should be neovascular AMD (wet AMD)
Dear Carlos,
I fully agree with you, as far as the neovascular AMD term is concerned.
But why calling this form of disease “wet”? Are you saying that “neovascular” always equals “wet”?
Leakage, as you mentioned, is secondary to neovascularization. In other words, leakage is just a sign (obviously not a source) of CNV activity.
There is neovascularization that is clinically not “wet” and on the other hand there is also non-neovascular AMD that is accompanying by fluid under the sensory retina - so is it “wet” or not? Obviously, we do not want to call the latter wet.
Sincerely,
Bart
Just to add our group opinion on this subject, probably there are more types than 2 for AMD. That could explain some of the strange behaviors of some patients from the clinical or therapeutic point of view. This is one of the problems of being to much simple with classifications. But until now there is no one better.
Wet AMD is both neovascular and exudative. Once these neo-vessels break through the Bruchs membrane and the RPE is interrupted , the barrier is affected and leak is there.