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Abstract
Background/aims Recent work has called into question the ability of visual acuity (VA) to accurately represent changes in visual function in infantile nystagmus (IN). This systematic review investigated factors affecting visual performance in IN, to guide development of suitable alternatives to VA.
Methods Included studies used an experimental manipulation to assess changes in visual function in people with IN. Interventional studies, case series and case studies were excluded. Six databases were searched in August 2023. Selection, detection, attrition and measurement bias were assessed. Due to heterogeneous methodologies, narrative synthesis was undertaken.
Results Eighteen relevant papers were identified, 11 of which complied with the review criteria. Articles were grouped according to the factor manipulated to evoke within-participant changes in performance (motion blur, psychological state, gaze angle or visual crowding). Optotype, image, grating and moving stimuli have been employed under varying lighting conditions and exposure duration.
Conclusion Several factors affecting visual performance should be considered when assessing visual function in IN. While maximum VA is a useful metric, its measurement deliberately minimises nystagmus-specific factors such as changes in visual performance with gaze angle and the ‘slow to see’ phenomenon. Maximum VA can be measured using the null zone, providing unlimited viewing time, reducing stress/mental load and minimising visual crowding. Gaze-dependent functional vision space is a promising measure which quantifies the impact of the null zone but does not consider temporal vision. Although no complete measurement technique has yet been proven, this review provides insights to guide future work towards development of appropriate methods.
- diagnostic tests/investigation
- psychophysics
- vision
- visual perception
Data availability statement
Data sharing not applicable as no datasets generated and/or analysed for this study.
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Data availability statement
Data sharing not applicable as no datasets generated and/or analysed for this study.
Footnotes
Collaborators Nystagmus U.K. Eye Research Group (NUKE): Gemma Arblaster (School of Allied Health Professions, Nursing and Midwifery, University of Sheffield, UK. Orthoptist Department, Sheffield Teaching Hospitals NHS Foundation Trust, UK), Perry Carter, Fatima Shawkat (The Eye Unit, University Hospital Southampton NHS Foundation Trust, Southampton, UK), Jonathan T Erichsen, Lee McIlreavy, Katherine Ward, J Margaret Woodhouse (School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK), Helen Griffiths (Sheffield Children’s Hospital, Sheffield, UK), Christopher M Harris (Royal Eye Infirmary, Derriford Hospital, Plymouth, UK), Harshal Kubavat, Sue Ricketts (Nystagmus Network, UK), Helen Kuht, Rebecca McLean, Frank A Proudlock, Mervyn Thomas, (Faculty of Medicine and Biological Sciences, University of Leicester, Leicester, UK), Helena Lee, Jay E Self (Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK), Maria Theodorou (Paediatric Ophthalmology and Strabismus, Moorfields Eye Hospital, London, UK), Nikita Thomas (Vision and Hearing Sciences Research Centre, Anglia Ruskin University, Cambridge, UK).
Contributors Drafting the manuscript: BA; literature review: BA; manuscript revision: MJD, NUKE. MJD is guarantor.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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