Eye diseases | Not a therapy yet, but maybe a study

There are, among other things, age-related causes of retinal detachment, but inflammation or tumors can also play a role. Photo: IMAGO/BSIP There are said to be at least 8,000 rare diseases, and a good ten times as many diagnoses are contained in the current medical coding system ICD-11. Even specialists only oversee parts of it. As a rule, the path to diagnosing a rare disease is a long one. When the patient finally knows what he is probably suffering from, the next problem comes: There is no treatment.

There are now several medical options: Either only the symptoms could be treated - with no prospect of a cure. Or existing medications are used beyond approval, with the doctor bearing the liability risk and obliged to inform the patient. A third option is to participate in studies testing new medications.

Ophthalmologists are currently drawing attention to this variant with a campaign, more precisely the Working Group for Clinical Study Centers of the German Ophthalmological Society. The reasons for the “For More Seeing” campaign are quickly summarized: Potential study participants still rarely find the study that makes sense for them. And on the other hand, researchers cannot find enough test subjects. At the same time, many studies are underway on various rare eye diseases.

Hereditary diseases of the retina are also included. The retina is the entire light-sensitive inner layer of the eye. Common diseases include age-related macular degeneration (which affects the area of ​​sharpest vision on the retina) and diabetic retinopathy, vascular damage caused by diabetes. As a result of these and other conditions, vision impairment occurs, such as loss of central visual acuity, poorer vision in the dark or a narrowed field of vision.

Something similar happens with hereditary diseases of the retina. The cause is changes in genes that are important for the function and maintenance of retinal cells. The long list of known disorders includes Stargardt disease (mostly in children and adolescents) or achromatopsia, an almost complete color blindness combined with extreme sensitivity to light. According to Tobias Peters, head of the Eye and Ear Study Center at the University Hospital of Tübingen, more than 330 disease-relevant genes have now been described. Research is being carried out on many of them and various therapeutic approaches are possible.

Among other things, disease-causing genetic changes are partially eliminated with the help of RNA-like molecules. Optogenetics has recently received a lot of attention: Here retinal cells that have lost their sensitivity to light or have never been sensitive to light are genetically modified so that they respond to light again. This year the Nobel Prize in Medicine was awarded for basic research on this subject. According to Peters, photoreceptor and stem cell therapies that are intended to replace destroyed retinal cells are still in a very early stage.

Finding studies is one thing, deciding whether participation might make sense is another.

The first breakthrough in the field of gene therapy came with the approval of Luxturna in the USA in 2017. The European Medicines Agency (EMA) followed suit in 2018. This can help patients with certain RPE65 mutations. These lead to the failure of the enzyme of the same name. This makes it difficult for the retina to convert light into electrical signals. Severe visual impairments occur in childhood, starting with severe night blindness. With the therapy, a functional copy of the defective gene is introduced into retinal cells. According to Peters, it has not yet been possible to build on this success. Nevertheless, from his point of view, further studies give hope.

But how do patients and potential test subjects find their way in this highly specialized area? On the one hand, according to Peters, there are state and international registers, such as the German Register of Clinical Studies, in which studies can be specifically filtered by disease, or the EU Clinical Trials Register for clinical trials of drugs in the European Union. Although the registers offer a neutral overview, the input masks are not easy to use for medical laypeople.

That's why Peters refers, among other things, to patient portals. "Patient organizations also make a decisive contribution because many are in close contact with university research." In addition, in the case of publicly funded studies, it is mandatory anyway "that patient representatives are on board." In any case, interested patients can and should ask their family doctors and specialists. It might also be worth taking a look at the clinic websites. Finding studies is one thing, deciding whether participation might make sense is another.

“There are a lot of inclusion and exclusion criteria,” says Peters. These all have to be checked – and that can’t be done over the phone. Before taking part in the study, there are a number of examinations to be carried out: “The patient must be able to endure all these procedures, some of which can take three to four whole days.” However, this approach serves the safety of the patient.

An advantage for test subjects: "You gain a lot of knowledge about your own eyes during the course." This is not only what Peters says, but is also confirmed by a test subject, who is introduced by the experts with the first name Veronika. Her diagnosis is optic atrophy. There is currently no treatment option for this. Without treatment, the optic nerve would gradually atrophy - leading to loss of vision. The young woman received information about the study from several sources, including from the self-help association Pro-Retina.

She receives the therapy with an injection into the eye. »I have received the lowest dose so far. My eyesight has not deteriorated since I started taking part,” reports the young woman optimistically and recommends taking part in the study. Their study is the first such research approach to optic atrophy in 24 years.

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