So why can diagnoses be tough to come by? First and foremost, most eye doctors don’t see many patients affected by inherited retinal diseases, because the conditions are rare. They simply don’t have familiarity with them, even if they learned about them in medical school and during their residency training.

Another major reason diagnoses are tough is that some conditions can look the same to even a well-trained retinal specialist. For example, cone-rod dystrophy affects the macula, the central region of the retina, much in the same way that Stargardt disease does. X-linked retinitis pigmentosa (XLRP) and choroideremia can look similar in appearance. Sometimes it isn’t clear upon examination whether a young child has retinitis pigmentosa or a form of Leber congenital amaurosis.

Also, diseases don’t always behave the way experts expect them to. XLRP is a great example of this phenomenon. According to textbooks, XLRP only affects men; females are unaffected carriers. But in recent years, researchers have found that a surprising number of women have vision loss, sometimes severe, from XLRP.

Despite these challenges, there are things you can do to improve your chances of getting an accurate diagnosis:

Visit a Clinician at a Retinal Research Center
Academic research institutions are where most experts in inherited retinal diseases practice, and FFB funds many of them. Known as “clinician-researchers,” they have the most knowledge and the best tools to make diagnoses.

These centers are located in many major cities in the United States, Europe and Asia. While it can be financially and logistically difficult for some patients to visit these centers regularly, even one visit can make a world of difference in understanding a disease.

Contact the Foundation at 1-800-683-5555 or info@FightBlindness.org to find the research center most convenient for you. We also maintain a list of privately practicing retinal doctors who are knowledgeable about inherited retinal degenerations.

Get Genetically Tested
Finding the disease-causing gene is the key to making a definitive diagnosis. If you find the genetic defect, you have the answer. Furthermore, finding the gene can position you for clinical trials of emerging treatments.

Of course, the genetic-testing process can be a real bear. That’s because only about 45 percent of the genes that cause these diseases are known, and the discovery of new genes is a research effort that can take many years. It isn’t like getting your cholesterol checked at your local doctor’s office or lab — you won’t get an answer right away, and sometimes you won’t get an answer for years until the gene is identified during research.

Also, it is best to contact a specific research center, and potentially its genetic counselor, to get a genetic test. The Foundation has online genetic testing resources, and the company InformedDNA offers fee-based, genetic counseling services over the phone for people with inherited retinal diseases.

Be Persistent and Tenacious
I can’t say enough how important it is to advocate for one’s self in getting answers to questions about a diagnosis or genetic test results. While people might not always get the answers they want — e.g., “We can’t find your gene” — they should get an answer. At the end of the day, they must make the follow-up calls to get the information to better understand a condition and how to deal with it.

For those who do jump through all these hoops and can’t get a definite diagnosis, there is good news. The Foundation funds several emerging treatments — including drugs, gene therapies and stem cell treatments — that are designed to work for people with a wide range of diagnoses.

Many of these potential therapies are funded through our Translational Research Acceleration Program and positioned to move into human studies within the next few years.

Finally, the Foundation is funding a number of outstanding researchers, who, thanks to advancing technology, are continually improving their ability to find disease-causing genes and make diagnoses.

Clearly, there continue to be formidable challenges for doctors, researchers and patients, but we are getting more answers to inherited retinal diseases every day.

Photo: Courtesy of National Eye Institute

Dr. Robert MacLaren

I was very excited to learn here at ARVO that two early-stage gene therapy clinical trials – one for choroideremia taking place in the U.K., the other for autosomal recessive retinitis pigmentosa (arRP) caused by MERTK mutations underway in Saudi Arabia – are proceeding well thus far. It is important to keep in mind that safety is the primary focus in these Phase I studies.

Dr. Emad Abboud, from the King Khaled Eye Specialist Hospital in Riyadh, reported that three patients, all in their thirties, have been treated with the MERTK gene therapy. The treatment uses an adeno-associated virus 2 (AAV2) – similar to the AAV2 used in landmark vision-restoring gene therapy clinical trials for Leber congenital amaurosis – to deliver copies of the therapeutic gene to retinal pigment epithelial cells in the retina.

Thus far, the MERTK treatment has been safe in all three patients. The two patients who received the treatment in 2011 have reported that they are seeing better with their treated eye and can read more lines on an eye chart than they could before the treatment. One woman said, “I see with the operated eye many things in the kitchen that I couldn’t see before.” The third patient, treated in April 2012, has not had his vision tested since receiving the therapy.

This study is being performed in collaboration with Dr. Kang Zhang at the University of California, San Diego.

Dr. Robert MacLaren, who is conducting the choroideremia gene therapy clinical trial at Moorfields Eye Hospital in London and Oxford Eye Hospital in Oxford, said that six people have been treated thus far with no adverse effects. This therapy also uses an AAV2 to get copies of the healthy gene into the retinal cells.

Dr. MacLaren notes that all six patients entered the trial with relatively good vision, and the goal is to demonstrate that the treatment prevents vision loss. He estimates that it will take at least two years to determine if the patients’ treated retinas have less degeneration, and better vision, than their untreated retinas.

We need to keep in mind that these are very early results for just a handful of patients. Cautious optimism is in order. Not every treatment that enters a clinical trial will be a home run. But the progress is exciting, and we couldn’t have a better group of researchers on the front lines working to get these treatments out to the people who need them.

By the way, the Foundation funded critical lab studies that made both the choroideremia and MERTK gene therapy clinical trials possible.