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CME – What It Is, and Why People with Retinal Diseases Should Know About It

Dr. FishmanIn this Q&A, Gerald Fishman, M.D., a world-renowned clinical researcher and longstanding member of FFB’s Scientific Advisory Board, discusses cystoid macular edema (CME), a potentially damaging accumulation of fluid in the retina affecting up to 32 percent of people with retinitis pigmentosa (RP) and related conditions. It’s a complication that can make matters worse for retinas already fragile from degenerative disease. While diagnosis isn’t always straightforward, CME can be treated to minimize vision loss.

What exactly is CME?
It’s the buildup of fluid, usually in the central region of the retina called the macula, which gives us the ability to read, perceive colors and see in lighted conditions. CME is analogous to having a sponge that’s wet all the time. It eventually deteriorates. If the retina sustains and leaks fluid for a long period of time, it can lead to permanent breakdown of the retinal structure.

A supportive layer of cells called the retinal pigment epithelium (RPE) normally pumps the fluid out. But with CME, the RPE can’t keep up.

How is CME diagnosed?
CME often causes reduced or blurry vision, but there isn’t always a correlation early on between the fluid buildup in the macula and vision loss. This can be surprising. Regardless, patients should always see their doctors with a significant change in vision to address any potential problems, CME or otherwise.

Ultimately, only a doctor can make the diagnosis of CME. If there’s enough fluid in the macula, we’ll often see a honeycomb or four-leaf clover when looking at the back of the eye with an ophthalmoscope during an exam. But we can be fooled; the fluid is there, but we may not see these signs.

To make a definitive diagnosis of CME, we capture an image of the retina’s layers using optical coherence tomography (OCT), a technique employing infrared light. If the fluid’s there, the OCT will detect it.

Even if I don’t see evidence of fluid when looking at the back of the eye, I like to do a baseline OCT for all my RP patients to see if they have CME. OCT will also tell us something about the anatomy in and around the macula.

What retinal diseases can lead to CME?
CME most often occurs in people with night-blinding retinal diseases such as RP, Usher syndrome, choroideremia, gyrate atrophy and enhanced S-cone syndrome. Also, people with X-linked retinoschisis can develop cystic lesions, which are somewhat different from CME; they’re accumulations of fluid, which are treatable, but they don’t leak. We don’t see CME in juvenile macular dystrophies, such as Stargardt disease. It’s also rarely observed in cone-rod dystrophy.

What are the treatments?
My first line of therapy is a topical carbonic anhydrase inhibitor (CAI), such as dorzolamide, which helps the RPE pump the fluid out faster. Some physicians prefer oral CAIs first, because they’re stronger. But those can have unpleasant side effects, such as fatigue and tingling in the fingers and toes.

Other treatment options include steroids and non-steroidal anti-inflammatory drugs. Also, the age-related macular degeneration therapies — Lucentis, Avastin and Eylea — may be considered, because they reduce fluid accumulation.

Not every patient responds to treatment for CME, but this is true for many other drugs and conditions. In some cases, people may not show improvement for as long as four months. I like to see some movement by two months to justify continuing treatment.

In some cases, a patient responds for a while, but the CME recurs. So I’ll pull them off the drug for a few months and then re-start it. Sometimes, they show a positive response again.

Treating CME is an art, and with each case, I try to get better at practicing it.

One other important point: I always make sure the patient is getting the eye drops in their eyes. So I teach them how to do it. If the patient is a youngster, I instruct the parents.

Pictured, above: Gerald Fishman, M.D., director of The Pangere Center for Hereditary Retinal Diseases at The Chicago Lighthouse for People Who are Blind or Visually Impaired.


15 Responses to 'CME – What It Is, and Why People with Retinal Diseases Should Know About It'

  1. Christie says:

    Do you know any physicians who can treat RP in Pittsburgh?

  2. Lilia says:

    Interesting, I read an article just the other day that was published by MedScape that suggested the use of the NSAID bromfenac alone was equal or better for preventing cystoid macular edema than steroids. The article can be found here…http://www.medscape.com/viewarticle/824708

    • John Midgley says:

      There is a very simple, inexpensive and effective both preventative and therapy for macular edema which I have been using for several years now. It also effective in wet type AMD.

      The treatment is based on the work of Geoffrey Arden at Kings College in London and was/is recently being trialed under the name CLEOPATRA at Ashford William Harvey Hospital in Kent, UK.

      The method is simply to turn off the electrical currents from the eye’s rods by stimulating them with light at a wavelength at the peak of rod sensitivity which is 498nm (or turquoise to you and me) while you sleep. In fact stimulating in the general area is sufficient so 480 to 520nm wavelength is OK. This has the effect of preventing the onset of edemas and reversing them to some extent after they occur.

      The light level used is quite low. As opposed to the light masks used in the CLEOPATRA trials which are useful for quantified controlled trials I simply used 498nm GU10 form lighbulbs I had made up especially in China. The GU10 spot bulb is simply directed at the bedroom ceiling over my head. It runs from a 12V transformer at under half power but this is more than sufficient and the illumination level could easily be lower. In fact the use of a spot is unecessary and serves only to limit the illumination of my wife next to me. Despite this the entire room is lit up with a pleasing turquoise low level glow. Today alternatives include long strings of LEDS in a flexible clear plastic tube.

      The light level should be at such a level that it will pass the “Arden Hand Test”. To check this turn your head to the darkest side of the room whilst lying on your pillow in bed at night. Close your eyes and after a minute or so move your hand in front of your closed eyes. If you can just see a shadow i.e. just a darkening corresponding to the hand movement then your illumination level is fine. Typically this level is quite low and depends upon eyelid thickness and pigmentation etc. Ideally therefore make sure your light source is adjustable.

      It is important to take supplementary melatonin with this treatment as the light stimulation will reduce your own melatonin production. I would guess 3mg per night.

      RESULTS:
      After nearly four years post diagnosis a cyst in the right eye did not develop further and is virtually non-existent. A cyst in the left eye which was causing small but significant visual impairment has shrunk. In fact I have not been tested for over a year but can report my vision has improved to the point that with both eyes open I notice no distortion of my vision. I am effectively cured. I have had zero injections or any other medication.

      Different people will respond to this treatment with varying degrees of success. Mine has been very successful because I started very early indeed. The clinical trials are producing good results too.

      Simply put there is a very effective preventative for these two eye conditions. It is also an effective therapy. It is very cheap. You can buy your own system for $20/£15. Basically it is just a light bulb! In a hurry? Get a mains green LED bulb and put it in your bedroom till you can find the more pleasant dimmable turquoise ones.

      Please also note: I am not selling anything!

  3. Any Physicians in the Chicago area who treat RP? please reply…

  4. Chalena Mack says:

    Dr. Gerald Fishman is in Chicago Pangere Center

  5. It was so nice to read this article about Dr. Fishman. I worked for Dr. Fishman years ago at the Illinois Eye & Ear Infirmary. He was a great boss and the consummate professional and leader in the field contributing a substantial body of work on retinitis pigmentosa and macular degeneration. Great to see he is still hard at work.

  6. Ken says:

    I have using Dorzolamide drops 4-5 months and it is not helping. Please advise. Many thanks

  7. Chris says:

    Dr. Cushman was one of the doctors who helped save my left eye some 20 years ago at UIC. I had many issues with my eye, and cannot thank him and the medical team that worked on it enough. Visits to his office were always fun (i was 13 at the time), he would use hand puppets and magic tricks to ease the stress off of me as I would be getting evaluated. Sadly I don’t live in the area anymore and issues have arose with my left eye, but I would recommend him and his staff to anyone with serious eye issues.

    Thanks again for giving this kid a chance of living a normal like Dr. Fishman

    Christopher Faulkner

  8. I developed CME after cataract surgery and may have had it misdiagnosed as PCI, which was treated with a laser procedure that produced no effect. The retinal specialist decided not to prescribe any drops or pills, but went straight to an injection inside the lower eyelid with steroids. Does anyone this make sense, and why? I almost have a feeling he is going through the motions, leading up to a correcting, as he says nothing about expected improvement. There has been no improvement after the first injection btw.

  9. Donna M Duty says:

    I have a friend that has RP,she is 53 years old, she now has CME, she has seen 2 Dr’s that has released her because they don’t know where to go from here, we are close to Jacksonville Florida, can anybody suggest a great Dr anywhere close?

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