Physics of Fixational Eye Movements (PhysFEM)
This project - under the call "Physics of Life: Building Collaboration at the Life Sciences Interface", funded by UKRI and the Wellcome Trust - addresses the challenge of ever-present involuntary movements of our eyes by combining ideas, methods and people from theoretical physics of random motion, and from the life sciences of visual neuroscience and psychology.
Project Summary
How should a sensory system, such as vision or hearing, optimally sample the world? Too much detail takes too long, and too much resource to acquire and process; too little risks failing to capture the vital information on what is going on around us. Human vision is a fascinating example - for even when the gaze is 'fixed' onto a target object or performing a specific task such as deciding which of two objects is higher, the eyes are in constant, apparently-random, motion that we do not understand. One might assume that such involuntary movements of the eye could only 'blur' vision, but there are reasons to believe that they might actually enhance it. One reason for suspecting this is that we know that many aspects of vision have evolved towards the best performance possible.
This project - the Physics of Fixational Eye Movements (PhysFEM) - addresses the challenge of these ever-present involuntary movements of our eyes by combining ideas, methods and people from theoretical physics of random motion, and from the life sciences of visual neuroscience and psychology. The combination is new and potentially powerful: there is almost no realm of physics that does not think about finding paths of trajectories that optimise something. Examples arise in complex classical mechanics, quantum mechanics, and the thermal physics of random processes. These ideas from physics provide a natural but fresh way of thinking about the possibility that fixational eye movements optimise some aspects of vision. More than that, they bring new calculation methods to find such paths, leading to empirically testable predictions about how the eyes might move to maximise the information available given particular task-demands. The objective measurement of human visual performance under controlled conditions - the domain of 'psychophysics' - completes the iterative cycles of model predictions and testing.
Physics enters the experimental mode of this project also in terms of the equipment used in in the Oxford Perception Lab to measure eye movements. The team use 'adaptive optics' - first developed for large astronomical telescopes to correct the optical distortions of the atmosphere - to image the retina at the back of the eye whilst correcting for distortions in the eye's fluid-filled optical components. Such correction permits high-resolution imaging of individual cells in the human retina without any invasive procedure. The Adaptive Optics Scanning Laser Ophthalmoscope (AO-SLO) will perform three simultaneous tasks in PhysFEM: (i) projecting controlled images onto the retina; (ii) imaging the retina at the resolution of individual light-detecting ('photoreceptor') cells; (iii) measuring eye movements with unprecedented accuracy, under a series of specific visual tasks.
The findings of the project will be built into a growing, open-access computational tool for vision science and technology, ISETBio, through a collaboration with its originator and director at the University of Pennsylvania, USA. ISETBio is an open-source set of software tools that characterise the sensory processes of early vision, and provides a platform for realistic computational implementation and evaluation of models for how neural processing incorporates FEMs, and transferring this to the international community of researchers in biological- and computer-vision and medicine.
publications
Cui, J., Villamil, M., Schneider, A.C., Lawton, P.F., Young, L.K., Booth, M.J., & Smithson, H.E. (2024). Extended-period AOSLO imaging in the living human retina without pupil dilation: a feasibility study, Biomed. Opt. Express, 15, 4995-5008. https://opg.optica.org/boe/fulltext.cfm?uri=boe-15-9-4995&id=554268
Published Abstracts
Cui, J., Villamil, M., Ponting, S., Booth, M.J., & Smithson, H.E. (2024). Evaluating the Effect of Pupil Diameter Change on AOSLO Image Quality without Pupil Dilation, Optica Biophotonics Congress: Biomedical Optics 2024 (Translational, Microscopy, OCT, OTS, BRAIN), Technical Digest Series (Optica Publishing Group, 2024), paper TTu3B.7. https://opg.optica.org/abstract.cfm?uri=Translational-2024-TTu3B.7
Cui, J., Villamil, M., Hexley, A.C., Booth, M.J., & Smithson, H.E. (2024). Imaging reproducibility using an adaptive optics scanning laser ophthalmoscope without pupil dilation, ARVO Meeting Abstract, Invest. Ophthalmol. Vis. Sci, 65(7):5931. https://iovs.arvojournals.org/article.aspx?articleid=2799078
Young, L.K., Hexley, A.C., Read, J.C.A., Smithson, H.E., Tuten, W.S., & Roorda, A. (2023). Poster Session I: Does stimulus image quality affect fixational eye movement characteristics? Optica Fall Vision Meeting Abstract, Journal of Vision, 23(15):43. https://jov.arvojournals.org/article.aspx?articleid=2793161
Hexley, A.C., Young, L.K., Brainard, D.H., Roorda, A., Tuten, W.S., & Smithson, H.E. (2023). Contributed Session II: The relationship between temporal summation at detection threshold and fixational eye movements. Optica Fall Vision Meeting Abstract, Journal of Vision, 23(15):75. https://jov.arvojournals.org/article.aspx?articleid=2793129
Wang, M.,Hexley, A.C., Houston, A.J.H., Cui, J., Read, D., Smithson, H.E., & Brainard, D.H. (2023). Poster Session I: Vernier thresholds of a Poisson-noise-limited computational observer with and without fixational eye movements. Optica Fall Vision Meeting Abstract, Journal of Vision, 23(15):42. https://jov.arvojournals.org/article.aspx?articleid=2793162
Hexley, A.C., Young, L.K., McLeish, T.C.B., & Smithson, H.E. (2022). Measuring and modelling fixational eye movements, Vision Sciences Society Annual Meeting Abstract, Journal of Vision, 22(14):4304. https://jov.arvojournals.org/article.aspx?articleid=2785218
Conference Presentations
Hexley, A.C., Greene, M.J., Roorda, A., Tuten, W.S., & Smithson. H.E. Spatial and chromatic discrimination thresholds in small retinal patches that vary in local L:M cone ratio, International Colour Vision Symposium, Ljubljana, Slovenia, 5th-9th July, 2024.
Turner, D.J., Keesing, L., Gray, J., Morimoto, T., McClements, M.E., MacLaren, R.E., Hexley, A.C., Brainard, D.H., & Smithson, H.E. Testing the reliability and validity of Rayleigh matches and heterochromatic flicker photometry settings on an Arduino-based LED device. International Colour Vision Symposium, Ljubljana, Slovenia, 5th-9th July, 2024.
Cui J., A multi-functional adaptive optics retinal imaging platform for precision psychophysics and disease-related studies, The Oxford International Conference on Advanced Optics and Photonics 2024, Oxford UK, 1st-5th July, 2024. [Best Presentation Award selected by expert panelists]
Cui J., Villamil M., Hexley A.C., et al., Poster: Imaging Reproducibility Using an Adaptive Optics Scanning Laser Ophthalmoscope without Pupil Dilation, ARVO Annual Meeting, poster 5931, Seattle US, 5th-9th May, 2024.
Cui J., Villamil M., Ponting S., et al., Oral Presentation: Evaluating the Effect of Pupil Diameter Change on AOSLO Image Quality without Pupil Dilation, Optica Biophotonics Congress: Biomedical Optics, paper TTu3B.7, Fort Lauderdale US, 7th-10th April, 2024.
Wang, M. Talk: Simulations of Vernier thresholds unravel the role of fixational eye movements in visual sampling, Experimental Psychology Society London Meeting, University College London, 3rd-5th January, 2024.
Wang, M. Talk: Computational simulations of Vernier thresholds: role of fixational eye movements in visual sampling, Applied Vision Association Christmas Meeting, Royal Holloway, University of London, 18th December, 2023.
Wang, M. Poster: Vernier thresholds of a Poisson-noise-limited computational observer with and without fixational eye movements, Fall Vision Meeting, Seattle, 5th-8th October, 2023.
Smithson, H.E., Hexley, A.C., Regan, S.E., & Young, L.K. Fixational eye movements and L:M cone ratio, Colour Group of Great Britain, January Meeting, London, UK, 4th January, 2023.
Hexley, A.C., Regan, S.E., Young, L.K., & Smithson, H.E. Fixational eye movements and variation in the L:M cone mosaic, International Colour Vision Symposium, Heraklion, Crete, 1st-5th July, 2022.
FORTHCOMING
Villamil, M., Schneider, A.C., Cui, J., Young, L.K., & Smithson, H.E. (2024). Detecting and characterising microsaccades from AOSLO images of the photoreceptor mosaic using computer vision, Optica Fall Vision Meeting.
Wang, M., Read, D., Brainard, D.H., & Smithson, H.E. (2024). Information integration in early visual processing revealed by Vernier thresholds, Optica Fall Vision Meeting.
Coupette, F., Brainard, D.H., Smithson, H.E., & Read, D.J. (2024). The role of fixational drift in the Vernier task, Optica Fall Vision Meeting.
Read, D.J., Houston, A.J.H., Smithson, H.E., Brainard, D.H., Hexley, A.C., & Wang, M. (2024). Fixational eye movements and retinal adaptation: optimizing drift to maximize information acquisition, Optica Fall Vision Meeting.
Bagheri, Z.M., Schneider, A.C., Wang, M., Brainard, D.H., & Smithson, H.E. (2024). The effect of fixational eye-movements on the temporal summation at detection threshold: A simulation study, Optica Fall Vision Meeting.
media
Smithson, H.E. (2024, March). Do we all see the same colour? BBC World Service, CrowdScience. https://www.bbc.co.uk/programmes/w3ct4y5h
Professional development and public engagement
Smithson, H.E. (September, 2024). Adventurous paths in sensory neuroscience: Refreshing visual input via fixational eye movements. Celebrating Tom McLeish. Durham, UK.
Cui, J. (September, 2024). Organised and moderated webinar session on Accommodation and visual function for Optica Vision and Color Summer Data Blast. https://www.optica.org/get_involved/technical_groups/bmo/vision_and_color_summer_data_blast/
Smithson, H.E. (July, 2024). Eye spy! High-resolution imaging of the retina provides a window on brain health. The Oxford International Conference on Advanced Optics and Photonics (OIC). Oxford, UK.
Cui, J. (July, 2024). Committee member and session moderator of Oxford International Conference on Advanced Optics and Photonics. https://oic.lightconference.cn/
Smithson, H.E. (June, 2024). Perceptual processes that underlie performance on visual tasks. Pembroke 400 Festival. Oxford, UK.
Cui, J (June, 2024). Appointed lead guest editor of Photonics Special Issue Novel Techniques and Applications of Ophthalmic Optics. https://www.mdpi.com/journal/photonics/special_issues/YJ037NHUW0
Cui, J (April, 2024). Appointed committee member of Optica Applications of Visual Science Technical Group. https://www.optica.org/get_involved/technical_groups/bmo/applications_of_visual_science/
Smithson, H.E. (July, 2024). Eye spy! High-resolution imaging of the retina provides a window on brain health. The Oxford International Conference on Advanced Optics and Photonics (OIC). Oxford, UK.
Smithson, H.E. (December, 2023). Eye spy! Using the eye as a window on active processes of neural function and control. PoLNET3 Winter School. Durham, UK. https://www.physicsoflife.org.uk/winter-school-challenges-and-opportunities-in-physics-of-life.html
Smithson, H.E. (January, 2023). Can soft matter science help understand active processes of neural function and control? Leeds SOFI2 Medical Applications of Soft Matter, Online.
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Mengxin Wang and Zahra Bagheri were involved with the UNIQ Summer School (June, 2024) - the University of Oxford's Access Programme for students attending schools that might typically be under-represented at University. Mengxin and Zahra delivered workshops on Colour Vision.
News
September 2024: Congratulations to Jiahe Cui whose 'career case study' has featured in the Department of Engineering Science researcher newsletter and on the Athena Swan profile page which highlights career development in interdisciplinary research. https://eng.ox.ac.uk/about/researchers/researcher-profiles/career-case-study-jiahe-cui/
August 2024: Congratulations to Allie Schneider who was awarded an MSD Internal Pump Priming Grant (£11,355) on Precision eye tracking to detect latent abnormalities in early-stage Parkinson's disease.
July 2024: Congratulations to Jiahe Cui who was awarded the Best Presentation Award at The Oxford International Conference on Advanced Optics and Photonics 2024, Oxford UK, 1st-5th July, 2024. In the photos above, Jiahe delivers her presentation (left) and is pictured with expert panelists and fellow awardees (right).
May 2024: Congratulations to Dr Jiahe Cui who presented at the annual ARVO meeting in Seattle. In the photos above Jiahe is pictured (A) with her poster at the start of the poster session; (B) presenting to fellow conference attendees; (C) sharing her poster with Professor Austin Roorda (Advisory Board Member: University of California, Berkeley); (D) sharing her poster with Dr Niamh Winn (University of Pennsylvania).
December 2023: Congratulations to Dr Mengxin Wang (PDRA) who was awarded the Honourable Talk Prize for her presentation: Computational simulations of Vernier thresholds: role of fixational eye movements in visual sampling, Applied Vision Association Christmas Meeting, Royal Holloway, University of London, 18th Dec, 2023.
October 2023: Allie Schneider visited Dr Ramkumar Sabesan's Lab and was cone-typed, which will allow for experiments on visual sampling, relying on knowledge of the underlying cone mosaic in the retina.
March-April 2023: Allie Schneider visited Prof Will Tuten and Prof Austin Roorda's labs as a Visiting Scholar. They collaborated on AOSLO psychophysics experiments, which were presented at FVM (2023) and ICVS (2024).
Our Team
Professor Hannah Smithson (Co-PI) - University of Oxford
Professor Daniel Read (Co-PI) - University of Leeds
Professor Martin Booth (Co-I) - University of Oxford
Professor David Brainard (Collaborator) - University of Pennsylvania
Dr Allie Schneider (Research Co-I) - University of Oxford
Dr Mengxin Wang (PDRA) - University of Oxford
Dr Zahra Bagheri (PDRA) - University of Oxford
Dr Fabian Coupette (PDRA) - University of Leeds
Dr Jiahe Cui (PDRA) - University of Oxford
Dr Rebekah White (Administrative PDRA) - University of Oxford
Former Team Members
We are indebted to our friend and colleague, Professor Tom McLeish. Tom was one of the original co-PI's on this project and the insights, questions, ideas, warmth and passion that he brought to the project are a source of inspiration to the current team.
We are also very grateful to Dr Alex Houston who was a PDRA on this project and maintains collaborative links with the current team.
Advisory Board
Professor William Bialek - Princeton University
Dr Jenny Bosten - University of Sussex
Professor Philip Nelson - University of Pennsylvania
Professor Austin Roorda - University of California, Berkeley
Fixational Eye Movements
When you are fixating on a stimulus such as the Landolt C (left image), your eyes do not stay perfectly still, but rather they make constant, rapid motions to translate the stimulus across the retina. Such fixational eye movements are crucial to your perception; without them, the area of your retina that you are using to view the stimulus would adapt to the stimulus and your percept would fade. Note the Landolt C stimulus energy distributed on the retina as shown in green (middle and right images) is blurred due to optical aberrations and eye motion. There are various ways in which the eye can translate the stimulus over your retina, and here in magenta we show a couple of example eye movement paths during a 500 ms period of fixation. The green is the photon distribution that would occur after not only the aberrations but also the eye movement trace in the magenta.
Forthcoming Events
No forthcoming events.
Past Events
Advisory Board Meeting: October 2nd-3rd, 2024; Pembroke College, University of Oxford.
Project Team Meeting: July 2nd-3rd, 2024; Pembroke College and Department of Experimental Psychology, University of Oxford.
Project Team Meeting: April 18th-19th, 2024; Pembroke College and Department of Experimental Psychology, University of Oxford.
Advisory Board Meeting: December 14th-15th, 2022; Pembroke College, University of Oxford.
Gallery
October 2024: Advisory Board Meeting, Pembroke College, University of Oxford
July 2024: Jiahe Cui helping conference attendees at the registration desk for the Oxford International Conference on Advanced Optics and Photonics (OIC).
July 2024: Jiahe Cui moderating an oral session for early career researchers and presenting a conference gift to Dr Yuqi Tang from Southeast University.
June 2024: Colour Vision Lab at the UNIQ Summer School.
May 2024: Jiahe Cui visiting Dr. Ramkumar Sabesan's lab at the University of Washington with fellow ARVO conference attendees.
April 2024: PhysFEM project team members came together for an in-person Project Team Meeting. The team met in the Department of Experimental Psychology and Pembroke College, University of Oxford. During the meeting, team members presented up-to-date results and short experiments were carried out on the Oxford AOSLO to demonstrate current imaging capabilities. It was a wonderful opportunity to welcome our newer PDRAs (Fabian and Zahra).