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Bringing state of the art intraocular-pressure measurements to Central Europe

Fluid build-up in the eye can cause ocular hypertension, which usually does not have any symptoms but can lead to glaucoma, one of the main causes of permanent blindness.

Early diagnosis and treatment of ocular hypertension is usually highly successful in preventing glaucoma and saving vision. Screening and monitoring of disease progression is performed using non-invasive intraocular-pressure (IOP) instruments called eye-tonometers. The correct performance of these devices is essential to ensure the correct diagnosis and treatment.

However, at the start of 2017, PTB, Germany’s National Metrology Institute, was the only measurement institute in Europe with state-of-the-art capabilities in IOP metrology. This included the calibrations required to ensure traceability for standard tonometers as well as the research experience needed to adapt to the demands of new technological developments.

The now completed EMPIR project Developing research capabilities for traceable intraocular pressure measurements (16RPT03, InTense) helped change this situation.

InTense was a research potential project, which is a special type of EURAMET project specifically designed to help transfer metrological expertise and knowledge throughout Europe – especially in research areas considered to be of national and regional priority.

During the project PTB worked with CMI, the NMI of Czechia to establish a new centre of excellence for IOP in the Czech Republic. This centre is now operational and provides calibration and verification services in the field of IOP metrology, to international customers as well as training opportunities for European NMIs.

By focusing this expertise and knowledge at one site, the project has ensured that the existing (technical) state-of-the-art in IOP metrology is accessible to a broad range of countries through an efficient use of resources.

In addition to developing the new facility the project’s other achievements include:

• Publication of good practice guidelines for traceable IOP metrology – detailing such things as the requirements for instruments and facilities.
• Published a White Paper on the smart specialisation concept developed to ensure a coordinated and optimised Central European approach towards Intra Ocular Pressure (IOP) metrology.
• Produced a report on measurement uncertainty of non-contact eye tonometers.
• A second report was generated focusing on the most influential factors (new and existing ophthalmological measurands) that affect IOP measurements made by specific devices.
• Clinical studies were performed that focused on the influence of hypoxia, cornea and body position on IOP values.
• Development of an ‘artificial’ eye by the Slovak University of Technology and the Slovak Institute of Metrology (SMU) for the calibration of eye tonometers. The new transfer standard was then validated by comparison with standard silicon eyes in an international metrological comparison.
• Preparing the draft of a new OIML international recommendation on “Ophthalmic instruments – Non-contact tonometers”. Once approved this will complement the existing OIML R 145 “Ophthalmic instruments – Impression and applanation tonometers.”
• Supporting a “Strategic plan for a pan-European centre on medical device metrology”; with the main aim of ensuring a coordinated approach to ‘Medical Devices with a Measurement Function’ (MDFM) metrology which will play both a provider and a guidance role for interested NMIs and stakeholders.
• CMI, who coordinated the highly successful project have also started the process towards becoming a Notified Body under the European Medical Device Regulation (MDR) by the end of 2022.

The extended measurements for intra-ocular pressure will allow faster, more accurate, treatment for intra-ocular pressure and help save the vision of European citizens.

Dominik Prazak who coordinated the project said about the work performed:

"The fruitful cooperation of the European NMIs helped to establish the calibration, training and research capabilities for the intra-ocular pressure metrology and to maintain and develop them in the future".

Work continues in the small collaborative project Development of eye-tonometry in CEFTA countries (CEFTON, 20SCP02) which will engage with stakeholders to ascertain existing and planned intraocular-pressure metrology calibration services within the CEFTA countries. This will include responsible state authorities, calibration service providers and other governmental or non-governmental offices.

This EMPIR project is co-funded by the European Union's Horizon 2020 research and innovation programme and the EMPIR Participating States.

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