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Purpose Nystagmus is a disorder characterized by uncontrolled, rhythmic oscillations of the eyes. It often causes reduced visual function beyond reduced visual acuity alone. There is a paucity of literature regarding the public understanding of nystagmus, and there are no published data on the impact of the COVID-19 pandemic on people living with the condition. This study explores the self-reported impact of the COVID-19 pandemic on those with nystagmus, and examines both public understanding of how nystagmus affects people who have it and the perceptions of public understanding by those with the condition and their carers. Methods A qualitative questionnaire was designed following a stakeholder engagement process. This questionnaire was advertised via social media platforms and charity websites to achieve widespread recruitment. Data were collected between November and December 2020. Participants were divided into two groups based on their response to the question: “Do you, or anyone you know well, have nystagmus?”. Questions were posed to participants in a purpose-built, branching survey. The resulting data were analyzed using descriptive and inferential statistical methods. Results One thousand six hundred forty-five respondents were recruited, of which 849 (51.6%) answered “Yes” to the initial filtering question. Analysis showed that, broadly, public understanding of nystagmus differs from the perception of it by those with nystagmus and their carers, that the COVID-19 pandemic has had a significant impact on those with nystagmus, and that respondents who have met someone with nystagmus, even briefly, tend to have a greater understanding of the impact of the condition. Conclusion This study highlights the lack of public awareness regarding nystagmus and suggests opportunities to increase the awareness of nystagmus without the need for extensive knowledge of the condition. The COVID-19 pandemic has posed additional difficulties for those living with nystagmus, which is likely to be comparable among those with similar ocular disorders.

Background/Aims Children with Down’s syndrome (DS) are known to have poorer visual acuity that neurotypical children. One report has shown that children with DS and nystagmus also have poor acuity when compared to typical children with nystagmus. What has not been established, is the extent of any acuity deficit due to nystagmus and whether nystagmus impacts on refractive error is within a population with DS.\ud \ud Methods Clinical records from The Cardiff University Down’s Syndrome Vision Research Unit were examined retrospectively. Binocular visual acuity and refraction data were available for 50 children who had DS and nystagmus (DSN) and 176 children who had DS but no nystagmus. Data were compared between the two groups, and with published data for neurotypical children with nystagmus.\ud \ud Results The study confirms the deficit in acuity in DS, compared to neurotypical children, of approximately 0.2 LogMAR and shows a further deficit attributable to nystagmus of a further 0.2 logMAR beyond the first year of life. Children with DS and no nystagmus appear to have acuity that mirrors that of typical children with nystagmus, while children with both DS and nystagmus have a significant additional impairment. Children with DS have a wide range of refractive errors, but nystagmus increases the likelihood of myopia. Prevalence and axis direction of astigmatism, on the other hand appears unaffected by nystagmus.\ud \ud Conclusion Nystagmus confers an additional visual impairment on children with Down’s syndrome and must be recognised as such by families and educators. Children with both DS and nystagmus clearly need targeted support.

Infantile nystagmus (IN) is a pathological condition of continuous, horizontal eye oscillations. Despite ongoing eye movements, those with IN do not experience oscillopsia, i.e. the illusory perception that the environment is moving to-and fro. The correct use of neural compensation for their eye movements, just as in typical individuals, is hypothesised to account for this lack of oscillopsia. This neural mechanism requires that an estimate of eye velocity (‘extra-retinal signal’) be compared to an estimate of the motion of the retinal image (‘retinal signal’), and any difference due to object motion. Despite this hypothesis, there have been no previous investigations on how accurately those with IN can estimate object motion. \ud Even in typical adults, eye movement compensation is not perfect, which underlies a number of pursuit-based illusions. One such illusion, the Filehne illusion can be used to investigate the relative mismatch between the extra-retinal and retinal signals as individuals judge their perception of stationarity while attempting to follow a moving target. This illusion was used to investigate, through comparison with typical individuals, whether those with IN correctly recover object motion.\ud Experiments were conducted to characterise the ability of those with IN to fixate as well as follow targets, using a novel two-dimensional eye movement measure. Under repeated testing, the fixation gaze angle at which the IN oscillation is minimum (a null zone) was not consistent. Moreover, those with IN were unable to accurately or precisely follow targets using their slow phase. Results from a comparison of fixation and pursuit performance in those with IN suggested no difference in either the accuracy or precision. Importantly, the psychophysical judgements of those with IN pursuit eye movements are prone to similar compensation errors as typical controls. However, the mechanisms by which this is achieved will require further exploration.