Good Vessels- Bad Vessels

Two readers have written that they’re confused about the various bad and good vessels in AMD. I mentioned that Avastin® and Lucentis® stops the “bad vessels” from growing and leaking beneath the retina but doesn’t kill or get rid of them. That means that either of these drugs often has to be given repeatedly because the vessels can leak or even grow after the drug wears off.

I also mentioned that one possible solution would be combine treatment with either of these drugs with a low dose Visudyne or PDT treatment. Visudyne can get rid of abnormal vessels in AMD. The problem with Visudyne is that it can also damage normal capillaries in the choroid which can cause vision loss and increases the stimulus, (VEGF), for the abnormal vessels to return. It makes sense to use lower light doses to limit the damage. The Avastin or Lucentis is used to block any VEGF that is caused by the PDT. In this way, we hope that the vessels can be eradicated permanently without the need for repeated injections.

So we have the “bad vessels” in AMD. These vessels are called choroidal neovascularization because the start growing from the choroid. These vessels grow in places where they shouldn’t be and cause fluid, hemorrhage, and scarring.

The good vessels are the capillaries in the choroid which nourish the outer retina. Therefore we want to kill the choroidal neovascularization and not harm the choroidal capillaries.

This is analogous to chemotherapy for cancer. Cancer drugs selectively kill cancer cells because they are growing and spare most of the normal cells of the body. Of course these drugs aren’t perfect because our cells in the bone marrow, hair follicles, and gut also replenish themselves. That’s why cancer drugs can cause reduced blood counts, hair loss, and digestive problems as side-effects. Researchers are working feverishly to find cancer drugs that affect only the cancer cells. We are working feverishly to develop treatments that affect only the abnormal choroidal neovascularization.

I hope this helps clarify things for you.