What eye examinations have to do with the Nobel Prize

What is at issue

In the early 1990s, there was a spirit of optimism in ultra-short pulse laser physics. Scientists succeeded in generating ever shorter laser pulses, initially in the femtosecond range (10^-15s). It soon became clear that ever shorter pulses would enable the observation of ever faster processes, such as elementary processes in chemical reactions, for which Ahmed Zewail received the 1999 Nobel Prize in Chemistry.

Ultimately, the quest for increasingly shorter laser flashes led to the unimaginably short attosecond range (10^-18s): The groundbreaking experiment was carried out in 2001 at the Vienna University of Technology by Ferenc Krausz, winner of the 2023 Nobel Prize in Physics. These lasers can be used to observe exactly what happens when one or more electrons are ionized from an atom.

OCT: Femtolasers and their potential in Medicine

In the 1990s, Ferenc Krausz just dreamed of attosecond lasers. He and his research group ultimately solved key problems in laser technology using special mirrors (chirped mirrors) and titanium sapphire lasers. Eventually, they achieved 12 femtoseconds. Wolfgang Drexler, head of the CD Laboratory for CD Laser Development and their Application in Medicine, recognised the opportunities these lasers offered for Medicine. The shorter the laser pulse, the broader the range of wavelengths the laser beam contains. And the greater this wavelength bandwidth, the greater the resolution of a device that can now be found in almost every ophthalmologist's practice: optical coherence tomography (OCT), which is used for the early detection and treatment of retinal diseases. An OCT device works in a similar way to ultrasound, except that it uses light instead of sound. This allows for a completely contactless examination. The light can penetrate 2–3 mm less deeply than sound, but – depending on the bandwidth – it provides greater resolution. The advantage of OCT is its high resolution in the micrometre range, while its disadvantage is its low penetration depth. The eye is particularly suitable for this purpose because it is both transparent and small. Among other things, the CD Laboratory focused on examining the retina, which can be completely imaged with OCT due to its thinness (250–300 micrometres). 

Cooperation in the CD Laboratory

The CD Laboratory's commercial partner was a spin-off company founded by scientists at TU Wien, including Ferenc Krausz: FEMTOLASERS Produktions GmbH. The company was founded in 1994 and produced laser systems based on the results of Krausz's research. However, a powerful femtolaser alone is not enough to make an OCT device. The task of the CD Laboratory was therefore to make the new technology usable for medicine: mirrors, light sources, variability of the wavelengths used, more compact design and repeated tests to ensure reliability. The CD Laboratory was able to demonstrate that the device works and produces images that are needed in medical practice. Since then, these devices have been further developed and have become significantly more cost-effective. The successors to the original prototypes are now used to assist in the diagnosis and treatment of retinal diseases.

And today?

Four other CD Laboratories at MedUni Vienna have previously focused on various aspects of OCT. In the CD Laboratory for Ocular and Dermatological effects of Thiomers, which was active until 2021, the focus was already on the application of OCT, in particular for the detailed examination of the tear film on the eye. Work on the light source was no longer carried out in this laboratory. Instead, the focus was on adapting of the detector unit, optics and optomechanics (mirrors and lenses) as well as on applying machine learning for the temporal optimisation of data analysis.