In search of new methods: How multiple sclerosis can be detected at an early stage through an ultrasound scan of the eye

Dr. Felix Schmidt is a neurologist and specialist in multiple sclerosis. As a Clinician Scientist, he’s granted “protected time” to enable him to focus on his research project in addition to his work in patient care. He is testing a completely new method of diagnosing multiple sclerosis in a faster and simpler way – with an ultrasound scan of the eye. We talked with him about how the two things are connected, about the difference between clinical and scientific work and – not least – about his passion for travel and mountaineering.

Dr. Schmidt, what has an ultrasound scan of the eye got to do with multiple sclerosis (MS)?

MS is a chronic, inflammatory disease of the central nervous system. The most common first symptom among patients is an inflammation of the optic nerve, i.e. optic neuritis. 30 percent have it as their first symptom and a total of 60 percent of MS patients have one at some point in the course of the disease. This already shows the connection between MS and the eye. On the other hand, diagnosing optic neuritis is no trivial matter. This is the source of the dictum “The patient sees nothing and the doctor sees nothing.” One important clinical sign of optic neuritis is a so-called “RAPD”, a relative afferent pupillary defect. Here, the pupil light reflex is damaged. The pupil doesn’t contract when a light is shone into the eye, and sometimes even expands.  This makes it sound as if it’s simple and reliable to detect, but that’s only true of the very pronounced cases. In milder cases, misinterpretations can occur – and this is where the ultrasound method comes into play.

And can you describe how an ultrasound scan of the eye is carried out?

The patient lies down on the examination table with their eyes closed. Then the ultrasound probe is held against their lower eyelid and, using a torch, you shine light through their closed eyes. The light is nevertheless perceived by the eye and the pupil reacts. It’s as simple as any other ultrasound scan. The pupil is measured when at rest, as well as under the influence of direct and indirect light. We measure the pupil’s diameter and how fast the pupil contracts under the influence of light. To begin with, we successfully tried it out on healthy patients and published norm values. In the case of patients with RAPD, these values are pathologically altered. Our study is the first ever to examine pupillary function using ultrasound, and also the first study to examine that of MS patients with an RAPD. At the moment, it’s still only patients from the Charité, but in future we hope to be able to include patients from outside the Charité in the study.

Is it possible to measure pupil function in other ways too? What are the advantages of your ultrasound method?

Yes, there are other methods of measuring it. The gold standard is measurement with a special camera, the pupillometer. This is a special examination and, in the field of practice-based medicine, it’s predominantly only ophthalmologists who have such devices. However, pupil function is also simply estimated visually. The ultrasound method has a number of advantages. It’s more precise, because you can measure the millimeters precisely. This makes the method more objectifiable. You can also save the results and document the process. So, it’s not just a method for improving diagnosis, but can also be used for assessing the effects of therapy. In addition, ultrasound devices are much more common than pupillometers. So, our method is more easily accessible and applicable in the broader clinical field. It’s even conceivable that it could have further areas of application too. The fact that the eye doesn’t have to be open for the examination, but is closed, offers many possibilities – e.g. in examining coma patients or patients with traumatic brain injuries whose eyes are swollen closed.