NEW TREATMENTS, DRUGS TARGET AGE RELATED VISION LOSS

The University of Mississippi Medical Center (UMC) is leading the way in treatments for age related macular degeneration (ARMD), the main cause of severe vision loss among adults over the age of 60.

Helen Allen of Greenwood was referred to Dr. C. J. Chen, UMC professor and chair of ophthalmology, when she saw a black spot blocking the central portion of the vision of her left eye.

At 87, Allen had to have cataract surgery and just weeks later began to suffer from ARMD. ARMD consists of two types, “dry” or “atrophic” and “wet” or “neovascular.”

The dry type is caused by a generalized degeneration of the macular area and not associated with growth of new blood vessels and/or bleeding. This type of degeneration usually leads to a slow, gradual loss of central vision over many years.

People with the less common wet type ARMD may suddenly lose their vision, particularly in one eye. The wet type of ARMD is caused by the growth of abnormal blood vessels in the eye. If the blood vessels leak fluid or bleed into the eye, there may be abrupt loss of vision.

Allen experienced the “wet” type ARMD. 

“Degeneration can happen anytime. The cataract surgery had nothing to do with it,” Chen said.

The “wet type” ARMD is more devastating and is responsible for 90 percent of severe visual loss due to ARMD. An abnormal new vessels membrane complex develops from the choroids to invade the sub-macular area. This choroidal neovascular membrane (CNV) can develop outside the central foveal area or at the subfoveal area.

According to Chen, several treatments are available for the wet type ARMD at UMC.

They include laser photocoagulation if the neovascular membrane is extra-fovea located. “If the membrane is located at the sub-foveal area, laser treatment is usually not indicated,” Chen said. “Laser photocoagulation tends to destroy the photoreceptor cells at the same time when it destroys CNV and a central blind spot can result from the laser of the sub-foveal CNV.”

Pharmaceutical therapy is usually suggested or the treatment of sub-foveal CNV. Photodynameic therapy (PDT) with Visudyne was first approved for treatment of wet ARMD by FDA in 2000. An Anti-VEGF treatment with intraocular injection of Pegatanib Sodium (Macugen) was approved by FDA in 2004.

These treatments, which are offered at UMC, according to Chen, slow down the progression of the neovascular membrane and reduce the chance of the severe visual loss. Another treatment at UMC is intraocular injection of Ranibizumab (Lucentis) and was approved in July 2006.

“In the clinical trial, Lucentis injected monthly in patients provided visual acuity benefit that occurred over two years of treatment,” Chen said. “In a head-to-head comparison study between PDT and Lucentis, the results of preserving vision or improving vision for the wet type ARMD are much better with the Lucentis treated group.”

However, Allen was one of several patients who began treatments this summer when UMC made an additional treatment available for wet ARMD called intra-ocular injection of Bevacizumab (Avastin).

“Avastin has gone through the clinical trial and has been approved by the FDA for intravenous application to treat colon cancer,” Chen said. “The original trial was not designed for the ARMD.”

The dosage of off-label use of Avastin in wet ARMD is much smaller than the original approved one used for anticancer treatment, according to Chen.  It is injected into the vitreous cavity instead of intravenous application.

“The blood-retina barrier makes the systemic absorption of Avastin even smaller,” he said.

When treatments began, Allen’s left eye was 20/400. Today after three treatments in more than four months, her vision is 20/30”

Allen, who continues to drive and stay very active, is relieved that the treatments are working. And the drive from Greenwood to Jackson once a month doesn’t bother her a bit.

“I have fantastic children,” she said. “They take turns taking me for treatments. It’s just such a huge improvement.”

In the most recent poll among the members of the American Society of Retinal Specialists, 92 percent of the retina specialists responded had used Avastin. Ninety-nine percent of them indicated that Avastin was somewhat better or much better than the existing approved or covered therapies such as PDT treatment or Macugen.

“Ninety-six percent of the responders felt that Avastin was equal or safer than the existing approved therapies using PDT or Macugen,” Chen said. “In our own clinic experience, we confirmed the sight saving capability of the Avastin IO injection and have not experienced any systemic side effects or ocular complications.”

Patients who suffer from the dry type ARMD aren’t so lucky. And while UMC is currently conducting a clinical trial to study the efficacy of juxtascleral injection of Anecortave acetate suspension (Retaane) to prevent the progression of dry type ARMD to the wet type ARMD, there is still no effective treatment available for the dry type ARMD.

“The only suggested treatment is taking the antioxidants, vitamin C, vitamin E, betacarotene and zinc as a supplementary therapy recommended by the Age-Related Eye Diseases Study,” Chen said.

— Jenny Woodruff (1-8-07)

2007-01-05 00:00:00 16415