Friday, February 27, 2009

AMD Update 4: Does Visualizing RPE Cells Hold the Key to Understanding AMD?

The following press release from the University of Rochester describes a new technique for visualizing retinal pigment epithelial (RPE) cells. By being able to see these cells, researchers may be able to find the cause of age-related macular degeneration and come up with new treatments. This could be a “breakthrough” technology.

The new release was taken from the Retina News section of Ophthalmology Web

Dark Cells' Of Living Retina Imaged For The First Time

New Technique May Spot Evidence of Macular Degeneration Years Earlier

University of Rochester 2 / 26 / 2009

A layer of "dark cells" in the retina that is responsible for maintaining the health of the light-sensing cells in our eyes has been imaged in a living retina for the first time.

The ability to see this nearly invisible layer could help doctors identify the onset of many diseases of the eye long before a patient notices symptoms. The findings are reported in today's issue of Investigative Ophthalmology and Visual Science.

"Our goal is to figure out why macular degeneration, one of the most prevalent eye diseases, actually happens," says David Williams, director of the Center for Visual Science and professor in the Institute of Optics at the University of Rochester. "Macular degeneration affects one in 10 people over the age of 65, and as the average age of the U.S. population continues to increase, it is only going to get more and more common. We know these dark retinal cells are compromised by macular degeneration, and now that we can image them in the living eye, we might be able to detect the disease at a much earlier stage."

In 1997, Williams' team was the first to image individual photoreceptor cells in the living eye, using a technique called adaptive optics, which was borrowed from astronomers trying to get clearer images of stars. To image the dark cells behind the photoreceptors, however, Williams employed adaptive optics with a new method to make the dark cells glow brightly enough to be detected.

The cells, called retinal pigment epithelial, or RPE cells, are nearly black, and form a layer that recharges the photoreceptor cells of the eye after they are exposed to light, Williams explains. The photoreceptors contain molecules called photopigments. When light strikes these molecules, they absorb the light and change shape, sending a signal to the brain indicating they've "seen" light.

Courtesy of Vitreous-Retinal-Macular Consultants of New York

Mosaic photo of living RPE cells. Courtesy University of Rochester

Once a photopigment molecule absorbs light, says Williams, it needs to get recharged, so it is shuttled out of the photoreceptor and down to the RPE cells. The RPE cells recharge the photopigment molecules and send them back to the photoreceptors to start the process again. In addition, the RPE layer keeps the photoreceptors healthy by collecting and storing toxic waste products that are produced during the process of regenerating the photopigment. In macular degeneration, for reasons that are not yet completely clear, the RPE cells are unable to provide this support for the photoreceptors and both kinds of cells eventually die.

Given their critical role supporting the photoreceptors, Williams says that scientists will benefit from being able to image RPE cells in patients to see what is malfunctioning in individual cells.

To see these dark cells, Williams and his colleagues Jessica Morgan, postdoctoral fellow at the University of Pennsylvania, Alf Dubra, postdoctoral fellow in Williams' laboratory, Bob Wolfe, technical associate in Williams' laboratory, and Bill Merigan, professor of Ophthalmology, Visual Science, and Brain and Cognitive Sciences at the University of Rochester, exploit a trait of the toxic chemicals the RPE were collecting from the photoreceptors.

"These nasty chemicals fluoresce-they glow just a little under the right conditions," says Williams. "When you shine blue or green light into the eye, the chemicals in the RPE shine back green and yellow. It's an incredibly dim glow, but when we use adaptive optics, we can take pictures of these chemicals in individual RPE cells."

Williams says many scientists believed imaging single RPE cells in the living eye would be impossible. He says he wasn't even convinced it could be done. When he and his team imaged the first photoreceptors in 1997, the RPE cells appeared pitch black.

Williams and his team now hope to learn exactly how RPE cells are related to macular degeneration. At the moment, scientists aren't sure how the disease starts, but being able to monitor the health of individual RPE cells may help doctors begin to piece together a picture of what mechanisms are malfunctioning in the retina. Williams also says that since the technique may eventually be able to spot illness in the RPE long before the patient experiences symptoms, doctors could start patients on therapies early enough to possibly slow or stop the onset of macular degeneration. Currently, when a patient begins treatment, a great deal of irreparable damage has been done.

This research was funded by the National Institutes of Health.

Thursday, February 19, 2009

Menu – Part 12: More Updates, A First Report on the SOLX Titanium Sapphire Laser, and a History and Comments About Intrastromal Ablation

This menu contains two updates on the Avastin/Lucentis Controversy; two updates on the CATT Study; a third update on the NeoVista Epi-Retinal Strontium 90 system for treating AMD; and three updates on current and future treatments for both wet and dry AMD.

The menu also contains a first report on the SOLX Titanium Sapphire laser for treating glaucoma and an overview and history of lasers used for intrastromal ablation.

First, the Avastin/Lucentis updates:

Avastin/Lucentis Update 23: An Interesting Overview of the Controversy

Dr. Greg Rosenthal had an interesting take on the Avastin/Lucentis Genentech controversy, and with his permission, I posted his thoughts.

Avastin/Lucentis Update 24: Dispute Between FDA and Genentech

Always alert to gaining clarity on the ongoing controversy, I saw the WSJ Health Blog on the subject, and decided it should be part of my ongoing coverage.

In my continuing coverage of the (now) started CATT Study, I posted the following two updates:

CATT Study Update 7: An Interesting Commentary by Dr. James Folk

This is Dr. James Folk’s take on regardless which drug, Avastin or Lucentis, comes out on top in the CATT study, Genentech wins!

CATT Study Update 8: The Story Behind The CATT Study

In a private conversation with the sponsors of the CATT Study, I learned of an article about how the CATT Study was finally funded and started. I requested permission to reproduce the article and it was granted.

AMD Updates:

Thanks to the publishers of Ophthalmic Market Reports and Ocular Surgery News, I was able to provide useful information about current and future treatments for AMD.

AMD Cases in the U.S. by Type and Stage in 20007

This graphic from the 2008 ARVO Meeting, presents information on the number of people afflicted with AMD, both wet and dry.

AMD Update 2: Investigative Therapies Discussed at the 2008 AAO Meeting

Using information garnered at the 2008 AAO Meeting, Market Scope’s Ophthalmic Market Report put together two useful graphics showing investigative therapies discussed at the AAO and the pre-AAO Retina meetings, for both wet and dry AMD.

AMD Update 3: Current Studies for Treating Macular Degeneration

And, finally, the editors of OSN presented a table of current major AMD clinical studies underway.

NeoVista Epi-Retinal Strontium 90 Treatment for AMD: Update 3

The people at NeoVista provided me with the 18 month data for their Phase II feasibility study, presented at the 2008 Retina Society Meeting, which I promptly posted.

Following the announcement of FDA clearance for its treatment of glaucoma, I decided to write up the SOLX 790 Titanium Sapphire laser:

SOLX Titaniam-Sapphire Laser for Treating Glaucoma: A First Report

This laser joins the Argon laser used in trabeculoplasty (ALT) for treating glaucoma. It should also be assessed against the doubled YAG laser used in the SLT protocol.

And, finally, a history and current experiments using lasers to perform intrastromal ablation:

Intrastromal Ablation: A Technology Whose Time Has Come?

Since I was privy to the history of ISA, having consulted for two of the five companies involved, I believed I was the right person to present its history and to raise the questions that should be asked of current research.

Monday, February 09, 2009

AMD Update 3: Current Studies for Treating Macular Degeneration

In its upcoming February 25th issue, Ocular Surgery News presents a table of ongoing clinical trials for treating age-related macular degeneration. I have reproduced the table below.

For more information on any of these, or the 186 current open trials for treating age-related macualar degeneration, please go to Clinical By using the “Refine Search” tab, and putting in the name of any of the trials listed in the table into the search box, you should be able to gain more information about each.

(By right-clicking on the table image and opening in a new tab or window, a larger more readable version will appear.)