Prof. Dr. Hanna G. Zimmermann

Applied Research of the Visual System

Hanna Zimmermann is junior professor for "Applied Research of the Visual System" at ECDF and Charité - Universitätsmedizin Berlin since June 2022. Her research focuses on changes in the retina of the eye caused by diseases such as multiple sclerosis, Alzheimer's disease, stroke and cardiovascular disease. Her "Interdisciplinary Retina Research" group uses innovative digital technologies to apply images of the retina, also known as the retina, to improve medical care. 
 The retina is part of the central nervous system; the same nerve cells exist here as in the brain. If there is a loss of nerve fibers in diseases such as multiple sclerosis, this also affects the retina: Minimal changes in the thickness of the nerve layers occur. Unlike the brain, however, the retina is not enclosed by bone and is therefore accessible to high-resolution optical examination methods. Retinal examination is much easier and less expensive to perform than magnetic resonance imaging of the brain, currently the standard examination for multiple sclerosis. With the help of digital image processing, the subtle changes in the retina that result from MS can be made measurable. Zimmermann and her team are relying here on artificial intelligence, or more precisely on deep learning. This machine learning method allows, for example, precise measurement of changes in retinal layer thicknesses, but Deep Learning can also draw information about the course of the disease itself from the retinal images: "At the moment, we see three main applications: for diagnosis, risk assessment and monitoring the course of the disease, i.e. also checking for the response of a drug," says the junior professor about the goals of her research. Zimmermann and her team were able to show, for example, that patients with MS who have a thinner retinal ganglion cell layer have a higher probability of a further disease flare-up in the near future. If necessary, a more effective therapy can then be initiated preventively. Together with researchers around the world, Zimmermann is working to make retinal examination a standard part of multiple sclerosis diagnosis. 

Zimmermann sees great potential in retinal examinations, not only for nerve diseases but also for diseases in which a malfunction of the blood vessels plays a role. "During retinal examinations, blood vessels at the back of the eye can be identified particularly well and scientists can use digital methods to measure changes in their diameter, density or course. In the event of a heart attack or stroke, for example, such changes can indicate how likely it is that such an event will occur again. Patients at high risk can then be examined more frequently as a preventive measure.

Zimmermann and her team are currently investigating changes in the blood vessels of people suffering from post-COVID syndrome. The coronavirus can cause damage to the blood vessels, which is probably partly responsible for symptoms such as permanent fatigue. The retinal examination will therefore also be used in therapy research for this disease, which currently makes life difficult for millions of people.

"In the long term, we would like to see retinal examination become a routine examination, perhaps even in the family doctor's office. That way, various risk factors for neurological or vascular diseases can be identified, and these diseases can then potentially be treated earlier and better," Zimmermann says. Zimmermann works with images of the retina from equipment that is already widely used in many hospitals and eye care practices.  To extract meaningful information from these images using innovative digital methods such as deep learning, working across disciplines is essential: Zimmermann's team includes scientists* and PhD students with medical, scientific and IT backgrounds, as well as optometrists. There is also a close exchange with ophthalmologists. However, this interdisciplinarity is not a foregone conclusion: "It is important to me that we all look beyond our scientific horizons. As a data scientist, it is important to know where the images you work with come from: What kind of complaints do the patients have? What is happening in the body, and what might be causing the retinal changes we are finding? At the same time, it also helps medical professionals to understand the concept behind an analysis method in order to understand its potential but, above all, its limitations," says the junior professor.

Zimmermann studied physical engineering - medical physics at the Berlin University of Applied Sciences (formerly Beuth University of Applied Sciences) and subsequently earned her doctorate in medical sciences at the Charité - Universitätsmedizin Berlin. In addition to her scientific work, she also wants to take up the topic of digitization in her teaching: "There is still room for improvement in medical training when it comes to dealing with data processing programs and new digital tools. Yet these methods are already firmly anchored in medicine and will become increasingly important in the future. That's why I'm particularly keen to get female students interested in digital methods, which is a matter close to my heart in addition to my research."