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New Imaging Technique May Be Game-Changer for RP Clinical Trials

Image of an eyeFoundation-funded researchers are developing an innovative approach that would more quickly, accurately and objectively measure the ability of a therapy to slow or halt the progress of retinitis pigmentosa (RP). Known as EZ Width, it holds potential for reducing the time, cost and number of patients needed to determine if a therapy is working in a clinical trial.

Tracking vision changes during human studies is challenging because traditional measurements of vision — including those for visual fields (peripheral vision) and retinal sensitivity (as measured by an electroretinogram) — are quite variable and give different results even when used several times a day on the same patient. Using these measurements, clinical studies take a long time, because the amount of retinal degeneration has to exceed the amount of measurement variability to determine how well a treatment is working. If the clinical trial isn’t long enough, it is destined to fail.

Enter EZ Width, which David Birch, Ph.D., Retina Foundation of the Southwest (RFSW), and Don Hood, Ph.D., Columbia University, have been developing since 2008. EZ Width uses a technique known as spectral domain optical coherence tomography (SD-OCT) to capture detailed images of the many layers that make up the human retina. Drs. Birch and Hood have been able to correlate changes in layers of viable photoreceptors — a region known as the ellipsoid zone (EZ) — with changes in RP patients’ visual fields.

The photoreceptor layers are critical because without photoreceptors, we can’t see. Most important, the investigators are finding that the EZ Width measurement does not vary as much as the traditional methods, meaning that disease progression can be tracked more accurately and clinical trials can be shorter in duration.

The investigators tested their EZ Width technique in an RFSW clinical trial of docosahexaenoic acid (DHA) — a healthy fat found in coldwater fish and algae — for potentially slowing vision loss in people with X-linked RP. Final results of the study are forthcoming shortly, but regardless of whether DHA saves vision or not, the scientists were able to successfully correlate visual field changes with changes in EZ Width with minimal variability over one year.

EZ Width Graphic

In the recent JAMA Ophthalmology research paper on their EZ Width study results, the investigators note that the technique may be applicable to other retinal diseases, including choroideremia, Usher syndrome type 2, and Stargardt disease.

The ultimate goal is to get EZ Width validated as a clinical trial endpoint by the U.S. Food and Drug Administration. With the Foundation’s help and the assistance of other experts in the retinal research community, Drs. Birch and Hood are well-positioned to do that. It will take more time, money and testing — that’s always the nature of the research beast — but EZ Width has the potential to be invaluable in expeditiously moving several emerging retinal-disease therapies through human studies and out to the people who need them.

Pictured, above: Side view of a retina as captured by SD-OCT. The EZ Width is the yellow line extending between the arrows. The patient has advanced RP with significant loss of peripheral vision.


19 Responses to 'New Imaging Technique May Be Game-Changer for RP Clinical Trials'

  1. Irv Arons says:

    Another accomplishment in the field of helping those with RP should be noted: Dr. Sheila Nirenberg of Cornell Weill School of Medicine is one of this year’s MacArthur Genius Awardees. She is using optogenetics along with a mathematical code to bypass damaged photorecptors to allow the blind to see almost normally. (In animal models currently, but humans shortly.)See her discuss her work here (http://t.co/cZ2mZwPRuI)and read my description of her work here (http://t.co/YRqSQ8gk2G)

    Irv Arons

  2. Deborah says:

    This was a very informative article. I appreciate your information. Please keep articles like this coming!

  3. Pritpal Singh says:

    As i am suffering from RP, am eagerly waiting for the Treatment. Please tell when clinical trials begins??

    • EyeOnTheCure says:

      Pritpal, thanks for your comment. Are you interested in being a volunteer for a clinical trial study?

      If so, we would recommend that you visit http://www.ClinicalTrials.gov. We fund many clinical trials but do not operate the studies ourselves and so reaching out them directly may be the best way for you to find out more about where they are happening and if participating is an option.

      On http://www.ClinicalTrials.gov, which is maintained by the National Health Institute, you are able to search for Stargardt clinical trials by searching based on your disease. Each clinical trial listing will tell you more about what the study is about and how you can contact them to see if they are recruiting and what the participant criteria may be.

      We hope this information is helpful and encourage you to contact us for additional help at info@fightblindness.org for further information if needed.

  4. Deepa Damodar says:

    We live in India. My daughter suffers from low night vision due to retinitis pigmentosa. I would like to if there is any treatment to stop the degeneration of the retina.

  5. I have to and some of my family, I have been dreaming of a cure for this disease.

  6. linda horton says:

    My two older children have this disease it is very hard them both. Please let me know if there is any help out there it would be much appreciated. Thank you.

  7. linda horton says:

    Both of my older children have this disease it is very hard for them both. If there is anything out there that will help them please let me know it would be very appreciated. That you so much.

  8. Tad Wiler says:

    I have RP and my loss of sight has noticeably been reduced. I am willing yo do whatever I can to keep my vision or improve it. I can be reached at 214-537-6725

  9. sajad says:

    My son is suffering from retinits pegmentosa by brith.he is 19 years of age .please help me.i can do any thing please show me the way.

  10. M Miller says:

    Several family members have RP. Am having difficulty trying to get them into studies. Please help me find facilities.

    • Eye on the Cure says:

      We would recommend that you visit http://www.ClinicalTrials.gov. We fund many clinical trials but do not operate the studies ourselves and so reaching out them directly may be the best way for you to find out more about where they are happening and if participating is an option.

      On http://www.ClinicalTrials.gov, which is maintained by the National Health Institute, you are able to search for RP clinical trials by searching based on your disease. Each clinical trial listing will tell you more about what the study is about and how you can contact them to see if they are recruiting and what the participant criteria may be.

      We hope this information is helpful and encourage you to contact us for additional help at info@fightblindness.org for further information if needed.

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