Scientists from the International Centre for Translational Eye Research (ICTER) are developing a technique called flicker optoretinography (f-ORG), which may be applied in diagnosing certain visual disorders. It is the optical equivalent of flicker electroretinography (f-ERG), a valuable tool that has been used for decades to study the physiological functions of the retina.
Professor Maciej Wojtkowski's team focuses on the use of flickering light to stimulate the retina (f-ORG method). In 2022, in their previous publication on f-ORG, the ICTER team members showed that it was possible to perform f-ORG measurements in a large frequency range (up to 50 Hz). In their latest work, the ICTER research team proposed a new approach to f-ORG measurements allowing for quick determination of the frequency characteristics of photoreceptors. The results appeared in the journal Optics Letters.
'A flicker protocol with variable instantaneous frequency combined with appropriate light adaptation has two advantages. On the one hand, it enables rapid measurement of the frequency response characteristics of photoreceptors; on the other, it also makes it possible to shorten the time between measurements by avoiding several minutes of adaptation to darkness', says co-author of the paper, Dr. Sławomir Tomczewski.
Photoreceptors are the fundamental component of the entire vision process. These specialized cells that absorb light and trigger a specific physiological reaction in the body come in two varieties: cones (responsible for sharp colour vision) and rods (responsible for black-and-white vision in low light, e.g. after dark). To properly receive visual stimuli and perceive the world around us, we need both cones and rods in large quantities.
Many eye diseases have a complex structure-function relationship, and photoreceptor abnormalities often manifest themselves on various levels, including their appearance and function. The time interval between functional deficits and the perceived pathological changes in the eye is variable and difficult to determine, and psychophysical methods (e.g. microperimetry, tests of sensitivity to flickering light) and electrophysical methods (e.g. electroretinography) are used in ophthalmological practice.
In the standard approach, obtaining a full frequency response of the human eye photoreceptors to flicker requires a large number of measurements at separate stimulus frequencies and time-consuming data processing for each of these sets.
ICTER scientists have shown that there are no significant differences between results obtained using this new, fast approach and a separate frequency flicker ORG.
With this new method, in the future it will be possible to perform significantly fewer measurements and reduce the time required to conduct experiments and analyse data. Work is currently underway to explain the mechanism of the phenomenon used in ORG and its relationship with the vision process. Ultimately, the new tool developed at ICTER may deliver a new frequency response-based biomarker for early detection of retinal diseases and therapy monitoring.
Photoreceptors are the fundamental component of the entire vision process. These specialized cells that absorb light and trigger a specific physiological reaction in the body come in two varieties: cones (responsible for sharp colour vision) and rods (responsible for black-and-white vision in low light, e.g. after dark). To properly receive visual stimuli and perceive the world around us, we need both cones and rods in large quantities.
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