Clinical highlights – May 2025
neuroClues® has officially received its CE-marking as a Class IIa medical device, available for clinical use in Europe.
For this occasion, we have decided to highlight how neuroClues® can elevate your practice by focusing on the biomarkers it extracts and how proven research demonstrates their diagnostic value.
Previously, we’ve explored saccadic eye movements and their neural pathways, showing how abnormalities can offer valuable insights into brain health, particularly cognitive decline . In this blog, we take a closer look at the reliability of these oculomotor biomarkers and why that matters.
Enjoy the reading!
1. Reliability of Oculomotor Biomarkers
For a biomarker to be meaningful, it must be objective and consistent. Eye movement tasks, such as pro and anti-saccades, are increasingly recognized as sensitive indicators of brain function, with abnormalities linked to various neurological conditions.
To use these metrics in clinical or research settings, we first need to understand how they behave in healthy individuals: Are the values consistent within individuals over a period of time?
Knowing the normal range of variation allows us to determine whether a given result is truly atypical.
We have highlighted three key studies that address these questions. Together, they demonstrate that oculomotor parameters, measured with video-oculography, exhibit strong reliability within healthy populations, making them promising candidates for use as biomarkers.
Reliability over Time in Healthy Adults
Two large-scale studies have shown that oculomotor metrics (such as saccadic latency and error rate) can be measured with high precision and are remarkably consistent over time in healthy individuals. Let’s dive into them.
In this research, the team assessed the test–retest reliability of oculomotor tasks such as prosaccades and antisaccades. 21 participants (between 19 and 43 years old) were tested and then re-tested after after ~5 to 15 weeks to evaluate stability of oculomotor parameters and practice effects in healthy individuals.
The results were compelling:
🔹 Oculomotor performance remained stable over the period tested for most measures.
🔹 Antisaccade error rate, prosaccade latency, and antisaccade latency showed high test–retest reliability.
🔹 Within a single session, participants’ responses showed strong internal consistency.
These findings support the use of oculomotor tasks as reliable, non-invasive biomarkers. An important step in building their credibility in research and clinical settings [1].
1.Ettinger U, Kumari V, Crawford TJ, Davis RE, Sharma T, Corr PJ. Reliability of smooth pursuit, fixation, and saccadic eye movements. Psychophysiology [Internet]. 2003 Jul [cited 2025 Apr 15];40(4):620–8. Available from: https://onlinelibrary.wiley.com/doi/10.1111/1469-8986.00063
Complementing this, a large-scale study by Bargary et al. (2017) collected data from over 1,000 young adults to assess the reliability of various oculomotor measures. Participants performed tasks such as pro saccades and anti saccades, from which key parameters were derived, including latency and error rates.
To evaluate the stability of these traits, a randomly selected subset participants (~10%) was retested after a median interval of 18.8 days. This allowed the researchers to determine how consistent individual performance was across sessions.
Their analysis revealed that multiple measures, including latencies and error rates, demonstrated high test-retest reliability over several weeks within individual.
The findings:
🔹 Underscore the potential of oculomotor metrics for future use as biomarkers or endophenotypes
🔹 Open the door for research into associations with other traits such as sex, cognitive style, or personality [2]
2.Bargary G, Bosten JM, Goodbourn PT, Lawrance-Owen AJ, Hogg RE, Mollon JD. Individual differences in human eye movements: An oculomotor signature? Vision Res [Internet]. 2017 Dec [cited 2021 Dec 15];141:157–69. Available from: https://www.sciencedirect.com/science/article/pii/S0042698917300391
Together, these findings reinforce the robustness of saccadic parameters when collected with a standardized approach, supporting their potential use in longitudinal research and their role as reliable physiological measures.
Reliability over Time within Age Groups
Płomecka et al. (2020) investigated the reliability of latency and error rates in saccadic eye movement tasks using an internationally standardized antisaccade protocol. Their study included a large sample of both young and older adults who were tested twice, one week apart, to evaluate age-related stability of oculomotor measures.
They found that:
🔹In older adults, both reaction time and error rate across pro- and antisaccade tasks demonstrated good to excellent reliability.
🔹In younger adults, antisaccade reaction time and error rate were also highly reliable.
🔹However, prosaccade error rate showed lower reliability in younger adults, likely due to the very low number of errors typically made on this simpler task
The study reported some of the highest reliability values to date for these metrics in saccadic tasks. It demonstrates that oculomotor measures (especially when derived from a standardized protocol) are stable over a period of one week in healthy individuals, including older adults, and can reliably capture individual differences.
This has important implications:
🔹 Measures were especially reliable in older adults, suggesting the protocol’s suitability for aging populations and longitudinal studies
🔹 Supports the potential use of these oculomotor metrics as biomarkers for cognitive decline
🔹 Reinforces the need for standardized methodologies when assessing neurocognitive function across the lifespan
These results provide further evidence that oculomotor tasks can produce highly consistent markers over time, reinforcing their potential as biomarkers for cognitive function and decline.
3.Płomecka MB, Barańczuk-Turska Z, Pfeiffer C, Langer N. Aging Effects and Test–Retest Reliability of Inhibitory Control for Saccadic Eye Movements. eneuro [Internet]. 2020 Sep [cited 2023 Nov 29];7(5):ENEURO.0459-19.2020. Available from: https://www.eneuro.org/lookup/doi/10.1523/ENEURO.0459-19.2020
2. Clinical Implications with neuroClues
The literature examples discussed above indicate that oculomotor biomarkers are indeed highly reliable, demonstrating consistency across time and tasks in different populations. This reliability is a foundational requirement for any metric intended for clinical use, supporting their relevance as objective, quantifiable measures of brain function.
That is why our ongoing discussions with Constances, the mega-cohort of 220,000 healthy participants, are instrumental: they will help establish a solid reference for the normal range of oculomotor performance with neuroClues.
We have built our technology around this scientific foundation. With neuroClues®, these validated oculomotor biomarkers are now accessible in everyday clinical practice across Europe. Our CE marked device is designed to precisely capture these reliable metrics in a fast, reproducible, and standardized manner, providing a powerful and objective window into brain function.
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