Problems with PDT

I received this message a few weeks ago:

Hi Dr Folk, My mother just had a PDT (visudyne) treatment and her dark area of central vision just doubled after the PDT. Should she switch to Avastin® or proceed on the PDT therapy, the second of which is scheduled after 3 months.

My comment is that the results of the various Lucentis® trials show that it’s a better treatment than PDT or Macugen®. There have been no randomized trials on Avastin® but hundreds of thousands of injections of it have been given around the world for wet AMD. The consensus and articles on nonrandomized trials so far is that Avastin® has pretty results that are the same or close to that of Lucentis® which would also make it better than PDT. Therefore I’m not sure why your mother received PDT as first line therapy. .

PDT causes inflammation with increase fluid exudation beneath the retina and a stimulus for regrowth of revascularization. It can also cause closure of choroidal capillaries beneath the macula and bleeding beneath the retina. All of these affects can cause vision loss. I’m not sure why your mother lost vision.

The downside of Lucentis® and Avastin® is that they stop the abnormal vessels from growing and leaking but they often don’t cause them to close permanently. Therefore injections of either drug have to be given repeatedly. PDT can close vessels permanently but sometimes at a price of vision loss. Doctors are now trying to determine which combinations may be most effective. The most common combination that is used now is PDT using half the amount of laser dose followed the same day with an injection of Lucentis® of Avastin®. Dr. Augustin and colleagues in Karlsruhe, Germany, used a combination of PDT with Avastin® and intraocular Decadron®, (an anti-inflammatory steroid) and had good results (ref 1). They also did a partial vitrectomy which may or may not have been necessary. Therefore PDT is still used but almost always as part of a combination treatment.

I don’t know your mother’s case. Maybe she has a lot of vascular risk factors which could make Avastin® or Lucentis® a little risky. There is a concern that these drugs could increase the risk of thromboembolic events especially strokes but we don’t know this for sure yet. Given the poor response to PDT, I would recommend Avastin® or Lucentis® if the choroidal neovascular vessels are still leaking or active.

References:

1. Augustin, AJ, Puls, S, Offerman I, “Triple Therapy for Choroidal Neovascularization due to Age-Related Macular Degeneration. Vertportfrin PDT, Bevacizumab, and Dexamethasone. RETINA 27:133-140, 2007.

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