Let’s continue with the discussion concerning the treatment of wet AMD (see last blog). My colleague from Florida is correct that there were serious side effects when Avastin® was used in patients with metastatic colon cancer including hypertension, gastrointestinal perforations, and rarely pulmonary embolism and arterial thromboembolism. The dose in these patients was 5mg/kg. Someone who weighs a modest 154 pounds is 70 kilograms. That person would receive 350 mg of Avastin® intravenously every two weeks. An effective dose for AMD is 1.25 mg (280 times less) and is placed inside the eye. I believe that a systemic complication from this ocular dose would have to be exceedingly rare.

1. I use the visual acuity, the fluorescein angiogram, and the OCT to determine whether I think a given treatment is working. In my experience:
   When a patient returns with a two or three line loss of vision, that’s a bad sign, and usually means that the neovascularization is growing or, at the very least, is still active.
   
2. If the fluorescein angiogram shows that the neovascularization has grown after a treatment, that is a bad sign.
   
3. If the OCT shows fluid under or within the retina after treatment, that is a moderately bad sign.

In my experience, if patients return with sharply reduced vision or a larger membrane after treatment, they usually don’t do very well in the long-run, even if that treatment is continued. The patients who do well long-term, usually are doing well after the first or second treatment. They come back with stable or improved vision, an inactive neovascular membrane on FFA, and less fluid on OCT.

So when should you consider switching treatments? I said that I would try Visudyne® with intravitreal Kenalog® once or inject Macugen® two or three times and then reassess how the patient is doing. If the patient has reduced vision and a larger membrane, I probably would switch treatments. The exception to that rule is that many patients who are treated with Visudyne®, (especially if Kenalog® is not used), still have fluid at their three month visit. A little remaining fluid on OCT will not dissuade me from repeating the Visudyne® treatment so long as the vision and neovascularization is relatively stable.

Maybe I’m not waiting long enough for the Macugen® to kick in, but if a neovascular membrane is growing and the vision is going down after two or three injections, I just can’t see how the treatment is “working” and I don’t think the final visual acuity is going to be very good. In these cases, I’ll try something else.

That’s my opinion. Please write to express yours. Thanks!