(PhysicsWorld) Researchers at Aarhus University in Denmark have tested optically pumped magnetometers (quantum sensors that detect magnetic fields that are over one billion times smaller than the earth’s magnetic field) to replace the painful but standard clinical method for measuring the function of the human retina. The standard procedure typically uses either a contact lens electrode or a fibre electrode to record retinal activity, both of which require physical contact with the eye, and therefore cause discomfort for the patient.
Recent advances in quantum technology have enabled the design and commercial production of lightweight and flexible OPM sensors, such as those being incorporated into magnetoencephalography scanners.
While retinal response is typically detected via electrodes, which measure the electrical activity from the eye surface, the OPM sensors instead record the corresponding magnetic field induced by this electrical activity. The resulting magnetoretinograms circumvent the need for direct contact with the patient’s eye.
At Aarhus University, the researchers placed multiple OPMs close to a participant’s eye while performing routine retinal measurements, using a fibre electrode and a flashing light stimulation.
Interestingly, artefacts due to eye blinks were reduced without the fibre electrode, as the OPMs offered a more comfortable scanning environment. However, the OPMs still suffered from a lower signal-to-noise ratio than the fibre electrode, likely due to a noisy magnetic environment.
As the magnetic fields originating from the retina are much smaller than the residual environmental magnetic field, the researchers operated the OPMs in a magnetically shielded room, to screen out some of this magnetic noise. They note that additional cost-effective active magnetic shielding could reduce this interference, resulting in a comparable signal-to-noise ratio to the ERG.