Glaucoma is the most common cause of blindness worldwide and, with a prevalence of 2-4% of people over 65 in Germany, is responsible for 1000 new cases of blindness each year. These not only have a negative impact on those affected, but also cause economic damage to the healthcare system. In high-technology nations such as Germany, where society is increasingly aging, the number of people affected by glaucoma will continue to rise. 
In the disease, neuronal ganglion cells in the optic nerve degenerate due to an undersupply of nutrients, which eventually leads to blindness of the affected person. Elevated intraocular pressure (IOP) is a major risk factor and lowering it describes the only medical approach to treatment, although lost vision cannot be restored.  For optimal diagnosis and treatment planning of glaucoma, the acquisition of a daily pressure curve is necessary. For this purpose, the measurement principle must be very gentle for the patients, since measurements are performed very frequently. Therefore, the measurement principle is best contactless and ideally can be used by the patient independently in the home environment. Since there are no cures for the disease so far, but only delaying therapies, early diagnosis and continuous monitoring is the most cost-effective and promising way for patients and payers.
Elevated intraocular pressure fluctuates widely throughout the day, which is why the pressure must be monitored continuously. Several technologies are available for this purpose, but so far they are only used in the doctor’s office and/or mechanically deform the eye with a stamp to measure the current pressure. These measurement procedures cannot be performed by the patient himself and are medically harmful to the eye, as they are not contactless and require anesthesia of the cornea. As a result, these measurement procedures are not suitable for frequent measurements to record diurnal pressure fluctuations.
In order to protect the users, a concept was developed at BIMAQ, in which the IOP is determined contactless from the vibration characteristics of the eye. The principle is implemented as a self-tonometer. Since the measurement is indirect and depends on the handling of the device, the results are to be validated by additional sensor technology and by machine learning (ML). This represents the core of this research work.
The aim of the research project is to specify and validate the contactless measurement method of the self-tonometer. To this end, the previously indirect measurement method, in which the reaction of the corneal movement resulting from the excitation signal on the air column and on the microphone is recorded, is now being extended to include direct optical recording of the corneal movement. With the more precise sensor data, it is possible to improve the signal evaluation and additionally identify failed attempts to provide the user with immediate feedback on the measurement performed. For this, the positioning and miniaturization of the sensors must be considered and a basic set of data must be generated to serve as a basis for ML. This work aims at measurement uncertainties of maximum ±5 mmHg (k=2) for hand-held self-measurements in order to be able to fulfill the requirements for a successful medical approval procedure with this gentle measurement method.
Benefits and economic significance for SMEs
Around 50 million people worldwide suffer from glaucoma. For therapy, approximately 76,800 stents are used annually in Europe to reduce intraocular pressure, representing a market volume of 38.4 million euros. The costs of these interventions can be reduced by continuous monitoring with appropriate medication at an early stage. This results in the market potential for the non-contact self-tonometer. Self-tonometers on the market that measure pressure via an impinging probe are sold in a price segment of around 3,000 euros. Assuming that half of surgically treated patients can delay or even avoid surgery with a self-tonometer, this results in a Europe-wide market potential of around 115 million euros. The potential for improving the care situation is also evident in the SALUS project at Münster University Hospital. Due to the advancing digitalization in the field of medical technology, the market potential is expected to increase further in the coming years.
The added value for the SMEs involved comes from the different characteristics of the participants and their networking, from which both suppliers and companies bringing software and hardware into circulation benefit. In addition, some companies can be enabled to enter the strictly controlled market of medical technology, which significantly increases the competitiveness of participating SMEs. By using ML, incorrect applications and a resulting invalid measurement can already be detected during the measurement and reported back to the user. This opens up new quality standards for intraocular pressure measurement, which have the potential to replace the current gold standard. In addition, it is conceivable that the optical analysis of the oscillatory response of the cornea will provide the basis for further diagnoses, allowing the technology to be extended to other clinical pictures in ophthalmology.
An example scenario is the subsequent market access of the measurement device by distributing companies such as Tomey, which benefit from the expansion of their own product portfolio. Hardware components such as housings, sensors and electronics are sourced from Weiß Umformtechnik, MicroEpsilon and/or Sasse, which means they are directly involved in the value chain. Finally, the results of the project enable SMEs to tap into new, future-oriented markets such as communication technologies for Industry 4.0 and IoT as well as components for medical technology, which form a central component for digitalization in this area.
For further contact details, please contact the office. See contact details
- Friedrich-Alexander-Universität Erlangen-Nürnberg
Lehrstuhl für Fertigungsautomatisierung und Produktionssystematik (FAPS)
- Universität Bremen
Bremer Institut für Messtechnik, Automatisierung und Qualitätswissenschaft (BIMAQ)
Project Accompanying Companies
The Research Association 3-D MID is still looking for companies to accompany the project. If you are interested, please contact the office. See contact details