Impact of pulsed stimulation on objective and subjective visual acuity measurements in nystagmus

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Quanz, Khaldoon O. Al-Nosairy, Francie H Stolle, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7205585/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 04 Nov, 2025 Read the published version in Documenta Ophthalmologica → Version 1 posted 9 You are reading this latest preprint version Abstract Purpose Quanz et al. (2024) reported that participants with nystagmus had higher objective visual evoked potential visual acuity estimates (VA VEP ) by 0.12 logMAR relative compared to standard psychophysical VA (VA Psych_Stat ). The cause of this modest, but significant VA VEP overestimation remains unclear. Here we investigated its association with the pattern-pulse stimulation mode applied for steady state VEP recording for VA VEP estimation. Specifically, we tested whether psychophysical visual acuity to pulsed optotypes (VA Psych_Pulsed ) also exceeds standard optotype VA Psych_Stat . Methods Twelve participants with nystagmus were included in this analysis. VA VEP was determined for pattern-pulse steady-state VEP stimulation (Quanz et al., 2024) using EP2000, psychophysical VA was determined to stationary (VA Psych_Stat ) and to pulsed (VA Psych_Pulsed ) Landolt-C optotypes employing a modified version of the Freiburg vision Test (FrACT). Pulsed stimulus timing was identical for VEP and VA (40 ms on and 93 ms off, i.e at 7.5 Hz). In a separate measurement, fixation stability within the central 4° was determined using microperimetry (Nidek MP-1), and the eye with the stronger fixation instability was selected for the analysis (12 eyes). LogMAR differences were assessed with a paired t-test and the correlation of fixation stability and VA differences (DVA Psych = VA Psych_Pulsed – VA Psych_Stat ) was tested. Results VA Psych_Stat (0.43 ± 0.06 logMAR) and VA Psych_Pulsed did not differ from each other (0.45 ± 0.06 logMAR, P = 0.15), but from VA VEP (0.26 ± 0.08 logMAR, P = 0.02 and P = 0.01, respectively). There was no correlation of DVA Psych with fixation instability (r 2 = 0.002, P = 0.89). Conclusion Pulsed stimulation appears not to be the reason for the VA VEP overestimation. Further research should address whether differences in the spatial stimulus properties might be of relevance, as VA Psych is tested with optotypes, VA VEP with extended patterns. VEP nystagmus visual acuity fixation instability Figures Figure 1 Figure 2 Figure 3 Introduction Objective estimation of visual acuity (VA) is of paramount importance in ophthalmology particularly when standard psychophysical VA (VA Psych ) might be unfeasible or unreliable. Visual evoked potential based-assessment of visual acuity (VA VEP ) is regarded to provide a relevant option to obtain objective VA estimates [ 1 , 2 ]. Still, VEP-based VA estimation is facing challenges in certain conditions e.g., amblyopia [ 3 , 4 ]. Recently, Quanz et al. [ 5 ] reported a small but significant VA VEP overestimation in nystagmus, by on average 0.12 logMAR compared to VA Psych , that depended on the degree of fixation instability. In that study VA VEP was estimated with pattern-pulse stimulation, while VA Psych with static optotypes. In fact, VEP responses to pulsed stimuli are less reduced by nystagmus-like stimulus movements than those to non-pulsed (pattern-reversal) stimuli [ 6 ]. This prompts the question whether the VA VEP overestimation in nystagmus is due to the pulsed stimulation mode. For psychophysical grating acuity, pulsed and non-pulsed conditions have been compared and no difference has been found [ 7 ]. Critically, for optotype acuity, this has not yet been investigated. We aimed to fill this gap and tested the hypothesis whether pulsed optotypes yield better VA-values (VA Psych_Pulsed ) than static (VA Psych_Stat ), i.e., that the stimulation mode accounts for the mismatch of VA VEP and the routinely acquired VA Psych_Stat . Methods This study included participants from Quanz et al.s' study [ 5 ], where a detailed record on the procedures is given. It followed the guidelines of the Declaration of Helsinki, and was approved by the Ethics Committee of the Faculty of Medicine, Otto-von-Guericke University, Magdeburg (153/18). All participants gave written informed consent. Participants For this study, we included data from 12 participants (mean and range of age: 39, 20–63y; only the individual's eye with stronger fixation instability was included) with nystagmus from the Quanz et al. cohort [ 5 ], for whom also VA Psych_Pulsed data were available. For patient characteristics see Table 1 . Causes of nystagmus were idiopathic infantile nystagmus syndrome (INS; n = 5), albinism (AL; n = 5), achiasma (ACH; n = 1) or acquired nystagmus (AN; n = 1). Epilepsy, dizziness, and any eye diseases affecting visual function, e.g., diabetic retinopathy, were exclusion criteria. Table 1 Participant characteristics. ID Group Sex Age [years] Nystagmus Type Stereopsis* BCVA [logMAR] Eye† Fixation ± 2° [%] 1 INS f 21 J/H No 0.54 OD 42 2 INS f 42 J/H No 0.41 OD 86 3 INS m 29 P/H No 0.32 OS 37 4 INS f 56 J/H No 0.32 OS 99 5 INS m 51 J/H Yes 0.28 OS 74 6 AN f 42 J/H Yes -0.07 OD 99 7 AL f 23 J/H No 0.47 OD 74 8 AL m 51 J/H No 0.73 OS 91 9 AL m 63 J/H No 0.69 OS 99 10 AL f 20 J/H No 0.61 OS 36 11 ACH m 22 J/H No 0.27 OS 88 12 AL m 40 J/H No 0.57 OD 43 INS: idiopathic infantile syndrome (excluding albinism and achiasma); AN: acquired nystagmus (cause: hydrocephalus shunt surgery); AL: albinism; ACH: achiasma; f: female; m: male; J: jerk, P: pendular, H: horizontal; *Stereopsis test using Lang test; BCVA [logMAR]: best corrected visual acuity in logarithmic minimal angle of resolution; Eye†: eye with stronger fixation instability; OD: right eye; OS: left eye VA VEP estimation VEP check-size dependence (size range: 0.048-0.8°) was determined for pattern-pulse steady-state VEP stimulation (40 ms on / 93 ms off, 7.5 Hz; 50 cd/m 2 mean luminance and 40% contrast) at a viewing distance of 114 cm as described in Quanz et al. [ 5 ] using EP2000 [ 8 ]. Participants wore appropriate refractive correction, procedures followed ISCEV recommendations [ 1 ]. The VA VEP estimation followed Bach et al. [ 9 ]. Briefly, steady-state VEP amplitudes and significance-levels at the stimulation frequency were determined with a Fourier-analysis based approach [ 10 – 12 ] and subjected to a heuristic algorithm to determine the spatial frequency limit for VA VEP estimation with an acuity independent conversion factor [ 9 ]. VA Psych estimation Both best-corrected VA Psych_Stat and VA Psych_Pulsed were determined twice for testing at 114 cm using the Freiburg Vision Test (FrACT) with Landolt C optotypes [ 13 ]. Pulsed stimulus timing for VA Psych_Pulsed was identical with the VEP pulsed mode (40 ms on / 93 ms off, 7.5 Hz; 102 cd/m 2 mean luminance and 96% contrast). Microperimetry – Fixation stability The fixation stability within the central 4° was quantified using a fundus-controlled microperimeter (MP-1 microperimeter, Nidek, Padova, Italy). The fundus-motion was tracked at 25 Hz for an epoch of 30 s, where participants were asked to fixate a central target. Analysis and statistics Normality was confirmed with the Shapiro-Wilk test and consequently parametric statistical testing was applied. One-sided paired t-tests were employed to determine whether VA Psych_Pulsed exceeded VA Psych_Stat and VA VEP exceeded VA Psych estimates. Pearson correlation (r 2 ) explored how DVA Psych (VA Psych_Pulsed – VA Psych_Stat ) depended on fixation instability within the central 4°. Results An overview of the mean VAs, VA Psych_Stat , VA Psych_Pulsed , and VA VEP is given in Fig. 1 . We observed a significant overestimation of VA VEP (0.26 ± 0.08 logMAR) compared to both VA Psych_Stat (0.43 ± 0.06 logMAR, P = 0.02) and VA Psych_Pulsed (0.45 ± 0.06 logMAR, P = 0.01). Notably, VA Psych_Pulsed and VA Psych_Stat did not differ significantly from each other (P = 0.15) and were highly correlated with each other (r 2 = 0.859, P < 0.001, Fig. 2 ). Finally, the difference between VA Psych_Pulsed and VA Psych_Stat did not correlate with the degree of fixation instability (DVA Psych , r 2 = 0.002, P = 0.89, Fig. 3 ). Discussion We found similar VA Psych for static and pulsed optotypes in nystagmus patients, and no dependence on the degree of fixation instability. It is concluded that the previously observed mismatch of VA VEP and VA Psych in nystagmus is not related to the difference in stimulation mode between standard psychophysical VA estimation ('static') and VEP based estimation ('pulsed'). While we are, to our knowledge, the first to compare psychophysical VA for static vs pulsed optotypes stimulation in nystagmus patients, there is a previous investigation of this issue for psychophysical grating acuity [ 7 ]. Dunn et al. report similar findings to the present study; they compared psychophysical static grating VA to tachistoscopically flashed (0.76 ms) patterns and failed to find a difference in nystagmus and healthy controls. Taken together, it appears that pulsed stimulation does not affect psychophysical VA estimates in nystagmus. In conclusion, the stimulation time course does not appear to be an explanation of the VA VEP overestimation in nystagmus. In search of an alternative explanation, it should be noted that VEP stimulation employs extended patterns, namely checkerboards, as opposed to optotype stimulation in VA Psych measurements. Taken together, our report indicates the need for further research into the mechanisms contributing to the slight, but significant VA VEP overestimation in nystagmus given the absence of an effect of pulsed stimulation. Declarations Conflict of interest. All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or nonfinancial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript. Ethical approval. All procedures performed were in accordance with the ethical standards of the institutional and/or national research committee (Otto-von-Guericke University Hospital/ OVGU ethical committee) and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Informed consent. Informed consent was obtained from all individual participants included in the study. Statement on the welfare of animals. This article does not contain any procedures with animals. Statement of human rights. All procedures performed in this study were approved by the ethical committee of Otto-von-Guericke University and were in accordance with tenets of Helsinki Declaration. Funding We gratefully acknowledge support by the Deutsche Forschungsgemeinschaft (Project #435838478, grants HO 2002/22–1 & HE 3504/9–1). Open Access funding enabled and organized by Projekt DEAL. Author Contribution E.V.Q., M.B.H., K.A-N, M.B.: Study concept and design. E.V.Q., J.K., F.HS.: Investigation. E.V.Q., M.B.H., K.A-N: Data analysis. E.V.Q., M.B.H, K.A-N: Original manuscript draft. E.V.Q.; M.B.H.; KA-N; M.B.; S.H.; F.H.S.; J.K.: Interpretation of results, revision of the manuscript for important intellectual content, and approval of the manuscript. Acknowledgement We thank the study participants and the German nystagmus network (Nystagmus Netzwerk e.V.) for their support. Data Availability Data is available upon request to the corresponding author. References Hamilton R, Bach M, Heinrich SP, et al. ISCEV extended protocol for VEP methods of estimation of visual acuity. Doc Ophthalmol . 2021;142:17–24. doi: 10.1007/s10633-020-09780-1 Hamilton R, Bach M, Heinrich SP, et al. VEP estimation of visual acuity: a systematic review. Doc Ophthalmol . 2021;142:25–74. doi: 10.1007/s10633-020-09770-3 Gopiswaminathan AV, Haldina J, Al-Nosairy KO, et al. Objective Visual Acuity Estimates in Amblyopia Are More Accurate With Optotype-Based P300 Than With VEP Measurements. Transl Vis Sci Technol . 2024;13:30. doi: 10.1167/tvst.13.12.30 Wenner Y, Heinrich SP, Beisse C, et al. Visual evoked potential-based acuity assessment: overestimation in amblyopia. Doc Ophthalmol . 2014;128:191–200. doi: 10.1007/s10633-014-9432-3 Quanz EV, Kuske J, Stolle FH, et al. Effect of nystagmus on VEP-based objective visual acuity estimates. Sci Rep . 2024;14:16797. doi: 10.1038/s41598-024-66819-y Hoffmann MB, Seufert PS, Bach M. Simulated nystagmus suppresses pattern-reversal but not pattern-onset visual evoked potentials. Clin Neurophysiol . 2004;115:2659–65. doi: 10.1016/j.clinph.2004.06.003 Dunn MJ, Margrain TH, Woodhouse JM, et al. Grating Visual Acuity in Infantile Nystagmus in the Absence of Image Motion. Investigative Ophthalmology & Visual Science . 2014;55:2682–6. doi: 10.1167/iovs.13-13455 Bach M. Visual Evoked Potentials “EP2000” – Computer system by Michael Bach. 2007. https://michaelbach.de/sci/stim/ep2000/ (accessed 8 January 2025) Bach M, Maurer JP, Wolf ME. Visual evoked potential-based acuity assessment in normal vision, artificially degraded vision, and in patients. British Journal of Ophthalmology . 2008;92:396–403. doi: 10.1136/bjo.2007.130245 Norcia AM, Clarke M, Tyler CW. Digital Filtering and Robust Regression Techniques for Estimating Sensory Thresholds from the Evoked Potential. IEEE Eng Med Biol Mag . 1985;4:26–32. doi: 10.1109/MEMB.1985.5006224 Norcia AM, Tyler CW, Hamer RD, et al. Measurement of spatial contrast sensitivity with the swept contrast VEP. Vision Research . 1989;29:627–37. doi: 10.1016/0042-6989(89)90048-5 Meigen T, Bach M. On the statistical significance of electrophysiological steady-state responses. Documenta Ophthalmologica . 1999;98:207–32. doi: 10.1023/A:1002097208337 Bach M. The Freiburg Visual Acuity Test - Automatic Measurement of Visual Acuity: Optometry and Vision Science . 1996;73:49–53. doi: 10.1097/00006324-199601000-00008 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 04 Nov, 2025 Read the published version in Documenta Ophthalmologica → Version 1 posted Editorial decision: Revision requested 28 Aug, 2025 Reviews received at journal 26 Aug, 2025 Reviews received at journal 21 Aug, 2025 Reviewers agreed at journal 04 Aug, 2025 Reviewers agreed at journal 30 Jul, 2025 Reviewers invited by journal 28 Jul, 2025 Editor assigned by journal 26 Jul, 2025 Submission checks completed at journal 26 Jul, 2025 First submitted to journal 24 Jul, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7205585","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":493226183,"identity":"a83cf093-c128-463d-af9f-2e147d113570","order_by":0,"name":"Elisabeth V. 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Al-Nosairy","email":"","orcid":"","institution":"Otto-von-Guericke University Magdeburg","correspondingAuthor":false,"prefix":"","firstName":"Khaldoon","middleName":"O.","lastName":"Al-Nosairy","suffix":""},{"id":493226187,"identity":"a6263eb5-97c5-48da-a1e3-ccf6b009ee2c","order_by":2,"name":"Francie H Stolle","email":"","orcid":"","institution":"Otto-von-Guericke University Magdeburg","correspondingAuthor":false,"prefix":"","firstName":"Francie","middleName":"H","lastName":"Stolle","suffix":""},{"id":493226188,"identity":"20378728-ca35-41fc-a421-b0ed3a1cbf86","order_by":3,"name":"Juliane Kuske","email":"","orcid":"","institution":"Otto-von-Guericke University Magdeburg","correspondingAuthor":false,"prefix":"","firstName":"Juliane","middleName":"","lastName":"Kuske","suffix":""},{"id":493226189,"identity":"99f9d859-ad81-4351-8df1-2fdcf1beeb11","order_by":4,"name":"Sven P. Heinrich","email":"","orcid":"","institution":"University of Freiburg","correspondingAuthor":false,"prefix":"","firstName":"Sven","middleName":"P.","lastName":"Heinrich","suffix":""},{"id":493226190,"identity":"14376d94-4b00-4221-96c6-d8739f3f46e8","order_by":5,"name":"Michael Bach","email":"","orcid":"","institution":"University of Freiburg","correspondingAuthor":false,"prefix":"","firstName":"Michael","middleName":"","lastName":"Bach","suffix":""},{"id":493226195,"identity":"75bafd23-2b07-4ca4-89c7-193bbcd17cc6","order_by":6,"name":"Michael B. Hoffmann","email":"data:image/png;base64,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","orcid":"","institution":"Otto-von-Guericke University Magdeburg","correspondingAuthor":true,"prefix":"","firstName":"Michael","middleName":"B.","lastName":"Hoffmann","suffix":""}],"badges":[],"createdAt":"2025-07-24 12:23:24","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7205585/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7205585/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10633-025-10060-z","type":"published","date":"2025-11-04T15:57:18+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":88035290,"identity":"add91f1f-acee-4275-ba3e-7d1af8d93cdf","added_by":"auto","created_at":"2025-07-31 16:12:05","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":100774,"visible":true,"origin":"","legend":"\u003cp\u003eOverview of VAs. (INS: idiopathic infantile syndrome); AN: acquired nystagmus (cause: hydrocephalus shunt surgery); AL: albinism; ACH: achiasma; note inverted y-axis such that better VAs are at top. The average VA (μ) is also shown for each stimulus type.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7205585/v1/67020e9203c2a96a82b18ae9.png"},{"id":88035295,"identity":"bd445d50-f4cf-4133-a78c-a9924f8add5e","added_by":"auto","created_at":"2025-07-31 16:12:05","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":121543,"visible":true,"origin":"","legend":"\u003cp\u003eCorrelation of VA\u003csub\u003ePsych_Pulsed\u003c/sub\u003e vs. VA\u003csub\u003ePsych_Stat\u003c/sub\u003e. Both VA measures were highly correlated. For abbreviations see Figure 1. Dotted line indicates the line of identity; note inverted axes such that better VAs are at top.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7205585/v1/523ba75f3d18f045bc98c90c.png"},{"id":88035832,"identity":"bd1c77ca-e555-4605-b547-ebabafb37440","added_by":"auto","created_at":"2025-07-31 16:20:05","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":60909,"visible":true,"origin":"","legend":"\u003cp\u003eCorrelation of fixation stability vs. ΔVA (ΔVA = VA\u003csub\u003ePsych_Pulsed\u003c/sub\u003e – VA\u003csub\u003ePsych_Stat\u003c/sub\u003e [logMAR]). No significant correlation was observed. For abbreviations see Figure 1.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7205585/v1/9e88c07bc52be3495959879c.png"},{"id":95564002,"identity":"6cf387b5-80a7-48b6-9a94-a7b660efb42d","added_by":"auto","created_at":"2025-11-10 16:06:20","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":796841,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7205585/v1/3780c517-b6ce-4413-90c0-7a1e5e870ec5.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Impact of pulsed stimulation on objective and subjective visual acuity measurements in nystagmus","fulltext":[{"header":"Introduction","content":"\u003cp\u003eObjective estimation of visual acuity (VA) is of paramount importance in ophthalmology particularly when standard psychophysical VA (VA\u003csub\u003ePsych\u003c/sub\u003e) might be unfeasible or unreliable. Visual evoked potential based-assessment of visual acuity (VA\u003csub\u003eVEP\u003c/sub\u003e) is regarded to provide a relevant option to obtain objective VA estimates [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Still, VEP-based VA estimation is facing challenges in certain conditions e.g., amblyopia [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Recently, Quanz et al. [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] reported a small but significant VA\u003csub\u003eVEP\u003c/sub\u003e overestimation in nystagmus, by on average 0.12 logMAR compared to VA\u003csub\u003ePsych\u003c/sub\u003e, that depended on the degree of fixation instability. In that study VA\u003csub\u003eVEP\u003c/sub\u003e was estimated with pattern-pulse stimulation, while VA\u003csub\u003ePsych\u003c/sub\u003e with static optotypes. In fact, VEP responses to pulsed stimuli are less reduced by nystagmus-like stimulus movements than those to non-pulsed (pattern-reversal) stimuli [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. This prompts the question whether the VA\u003csub\u003eVEP\u003c/sub\u003e overestimation in nystagmus is due to the pulsed stimulation mode. For psychophysical grating acuity, pulsed and non-pulsed conditions have been compared and no difference has been found [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Critically, for optotype acuity, this has not yet been investigated. We aimed to fill this gap and tested the hypothesis whether pulsed optotypes yield better VA-values (VA\u003csub\u003ePsych_Pulsed\u003c/sub\u003e) than static (VA\u003csub\u003ePsych_Stat\u003c/sub\u003e), i.e., that the stimulation mode accounts for the mismatch of VA\u003csub\u003eVEP\u003c/sub\u003e and the routinely acquired VA\u003csub\u003ePsych_Stat\u003c/sub\u003e.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eThis study included participants from Quanz et al.s' study [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], where a detailed record on the procedures is given. It followed the guidelines of the Declaration of Helsinki, and was approved by the Ethics Committee of the Faculty of Medicine, Otto-von-Guericke University, Magdeburg (153/18). All participants gave written informed consent.\u003c/p\u003e\u003cp\u003e\u003cb\u003eParticipants\u003c/b\u003e\u003c/p\u003e\u003cp\u003eFor this study, we included data from 12 participants (mean and range of age: 39, 20–63y; only the individual's eye with stronger fixation instability was included) with nystagmus from the Quanz et al. cohort [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], for whom also VA\u003csub\u003ePsych_Pulsed\u003c/sub\u003e data were available. For patient characteristics see Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Causes of nystagmus were idiopathic infantile nystagmus syndrome (INS; n = 5), albinism (AL; n = 5), achiasma (ACH; n = 1) or acquired nystagmus (AN; n = 1). Epilepsy, dizziness, and any eye diseases affecting visual function, e.g., diabetic retinopathy, were exclusion criteria.\u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eParticipant characteristics.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"9\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eID\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGroup\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eSex\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eAge [years]\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eNystagmus Type\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eStereopsis*\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eBCVA [logMAR]\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eEye†\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eFixation ± 2° [%]\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eINS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ef\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eJ/H\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.54\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eOD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e42\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eINS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ef\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eJ/H\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.41\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eOD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e86\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eINS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003em\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eP/H\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eOS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e37\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eINS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ef\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e56\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eJ/H\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eOS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e99\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eINS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003em\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e51\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eJ/H\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eOS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e74\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAN\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ef\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eJ/H\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eYes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e-0.07\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eOD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e99\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAL\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ef\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e23\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eJ/H\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.47\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eOD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e74\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAL\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003em\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e51\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eJ/H\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.73\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eOS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e91\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAL\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003em\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e63\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eJ/H\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.69\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eOS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e99\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAL\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003ef\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eJ/H\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.61\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eOS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e36\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eACH\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003em\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eJ/H\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.27\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eOS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e88\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAL\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003em\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003eJ/H\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003eNo\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.57\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003eOD\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e43\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"9\" nameend=\"c9\" namest=\"c1\"\u003e\u003cp\u003e\u003cem\u003eINS: idiopathic infantile syndrome (excluding albinism and achiasma); AN: acquired nystagmus (cause: hydrocephalus shunt surgery); AL: albinism; ACH: achiasma; f: female; m: male; J: jerk, P: pendular, H: horizontal; *Stereopsis test using Lang test; BCVA [logMAR]: best corrected visual acuity in logarithmic minimal angle of resolution; Eye†: eye with stronger fixation instability; OD: right eye; OS: left eye\u003c/em\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003e\u003cb\u003eVA\u003c/b\u003e\u003csub\u003e\u003cb\u003eVEP\u003c/b\u003e\u003c/sub\u003e \u003cb\u003eestimation\u003c/b\u003e\u003c/p\u003e\u003cp\u003eVEP check-size dependence (size range: 0.048-0.8°) was determined for pattern-pulse steady-state VEP stimulation (40 ms on / 93 ms off, 7.5 Hz; 50 cd/m\u003csup\u003e2\u003c/sup\u003e mean luminance and 40% contrast) at a viewing distance of 114 cm as described in Quanz et al. [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] using EP2000 [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Participants wore appropriate refractive correction, procedures followed ISCEV recommendations [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. The VA\u003csub\u003eVEP\u003c/sub\u003e estimation followed Bach et al. [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Briefly, steady-state VEP amplitudes and significance-levels at the stimulation frequency were determined with a Fourier-analysis based approach [\u003cspan additionalcitationids=\"CR11\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e–\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] and subjected to a heuristic algorithm to determine the spatial frequency limit for VA\u003csub\u003eVEP\u003c/sub\u003e estimation with an acuity independent conversion factor [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003cb\u003eVA\u003c/b\u003e\u003csub\u003e\u003cb\u003ePsych\u003c/b\u003e\u003c/sub\u003e \u003cb\u003eestimation\u003c/b\u003e\u003c/p\u003e\u003cp\u003eBoth best-corrected VA\u003csub\u003ePsych_Stat\u003c/sub\u003e and VA\u003csub\u003ePsych_Pulsed\u003c/sub\u003e were determined twice for testing at 114 cm using the Freiburg Vision Test (FrACT) with Landolt C optotypes [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Pulsed stimulus timing for VA\u003csub\u003ePsych_Pulsed\u003c/sub\u003e was identical with the VEP pulsed mode (40 ms on / 93 ms off, 7.5 Hz; 102 cd/m\u003csup\u003e2\u003c/sup\u003e mean luminance and 96% contrast).\u003c/p\u003e\u003cp\u003e\u003cb\u003eMicroperimetry – Fixation stability\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe fixation stability within the central 4° was quantified using a fundus-controlled microperimeter (MP-1 microperimeter, Nidek, Padova, Italy). The fundus-motion was tracked at 25 Hz for an epoch of 30 s, where participants were asked to fixate a central target.\u003c/p\u003e\u003cp\u003e\u003cb\u003eAnalysis and statistics\u003c/b\u003e\u003c/p\u003e\u003cp\u003eNormality was confirmed with the Shapiro-Wilk test and consequently parametric statistical testing was applied. One-sided paired t-tests were employed to determine whether VA\u003csub\u003ePsych_Pulsed\u003c/sub\u003e exceeded VA\u003csub\u003ePsych_Stat\u003c/sub\u003e and VA\u003csub\u003eVEP\u003c/sub\u003e exceeded VA\u003csub\u003ePsych\u003c/sub\u003e estimates. Pearson correlation (r\u003csup\u003e2\u003c/sup\u003e) explored how DVA\u003csub\u003ePsych\u003c/sub\u003e (VA\u003csub\u003ePsych_Pulsed\u003c/sub\u003e – VA\u003csub\u003ePsych_Stat\u003c/sub\u003e) depended on fixation instability within the central 4°.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eAn overview of the mean VAs, VA\u003csub\u003ePsych_Stat\u003c/sub\u003e, VA\u003csub\u003ePsych_Pulsed\u003c/sub\u003e, and VA\u003csub\u003eVEP\u003c/sub\u003e is given in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. We observed a significant overestimation of VA\u003csub\u003eVEP\u003c/sub\u003e (0.26\u0026thinsp;\u0026plusmn;\u0026thinsp;0.08 logMAR) compared to both VA\u003csub\u003ePsych_Stat\u003c/sub\u003e (0.43\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06 logMAR, P\u0026thinsp;=\u0026thinsp;0.02) and VA\u003csub\u003ePsych_Pulsed\u003c/sub\u003e (0.45\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06 logMAR, P\u0026thinsp;=\u0026thinsp;0.01). Notably, VA\u003csub\u003ePsych_Pulsed\u003c/sub\u003e and VA\u003csub\u003ePsych_Stat\u003c/sub\u003e did not differ significantly from each other (P\u0026thinsp;=\u0026thinsp;0.15) and were highly correlated with each other (r\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.859, P\u0026thinsp;\u0026lt;\u0026thinsp;0.001, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Finally, the difference between VA\u003csub\u003ePsych_Pulsed\u003c/sub\u003e and VA\u003csub\u003ePsych_Stat\u003c/sub\u003e did not correlate with the degree of fixation instability (DVA\u003csub\u003ePsych\u003c/sub\u003e, r\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.002, P\u0026thinsp;=\u0026thinsp;0.89, Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eWe found similar VA\u003csub\u003ePsych\u003c/sub\u003e for static and pulsed optotypes in nystagmus patients, and no dependence on the degree of fixation instability. It is concluded that the previously observed mismatch of VA\u003csub\u003eVEP\u003c/sub\u003e and VA\u003csub\u003ePsych\u003c/sub\u003e in nystagmus is not related to the difference in stimulation mode between standard psychophysical VA estimation ('static') and VEP based estimation ('pulsed').\u003c/p\u003e\u003cp\u003eWhile we are, to our knowledge, the first to compare psychophysical VA for static vs pulsed optotypes stimulation in nystagmus patients, there is a previous investigation of this issue for psychophysical grating acuity [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Dunn et al. report similar findings to the present study; they compared psychophysical static grating VA to tachistoscopically flashed (0.76 ms) patterns and failed to find a difference in nystagmus and healthy controls. Taken together, it appears that pulsed stimulation does not affect psychophysical VA estimates in nystagmus. In conclusion, the stimulation time course does not appear to be an explanation of the VA\u003csub\u003eVEP\u003c/sub\u003e overestimation in nystagmus. In search of an alternative explanation, it should be noted that VEP stimulation employs extended patterns, namely checkerboards, as opposed to optotype stimulation in VA\u003csub\u003ePsych\u003c/sub\u003e measurements.\u003c/p\u003e\u003cp\u003eTaken together, our report indicates the need for further research into the mechanisms contributing to the slight, but significant VA\u003csub\u003eVEP\u003c/sub\u003e overestimation in nystagmus given the absence of an effect of pulsed stimulation.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cb\u003eConflict of interest.\u003c/b\u003e All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers\u0026rsquo; bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or nonfinancial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript.\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eEthical approval.\u003c/strong\u003e\u003cp\u003e All procedures performed were in accordance with the ethical standards of the institutional and/or national research committee (Otto-von-Guericke University Hospital/ OVGU ethical committee) and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eInformed consent.\u003c/strong\u003e\u003cp\u003e Informed consent was obtained from all individual participants included in the study.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003ch2\u003eStatement on the welfare of animals.\u003c/h2\u003e\u003cp\u003e This article does not contain any procedures with animals.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eStatement of human rights.\u003c/strong\u003e\u003cp\u003e All procedures performed in this study were approved by the ethical committee of Otto-von-Guericke University and were in accordance with tenets of Helsinki Declaration.\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e\u003cp\u003eWe gratefully acknowledge support by the Deutsche Forschungsgemeinschaft (Project #435838478, grants HO 2002/22\u0026ndash;1 \u0026amp; HE 3504/9\u0026ndash;1).\u003c/p\u003e\u003cp\u003eOpen Access funding enabled and organized by Projekt DEAL.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eE.V.Q., M.B.H., K.A-N, M.B.: Study concept and design. E.V.Q., J.K., F.HS.: Investigation. E.V.Q., M.B.H., K.A-N: Data analysis. E.V.Q., M.B.H, K.A-N: Original manuscript draft. E.V.Q.; M.B.H.; KA-N; M.B.; S.H.; F.H.S.; J.K.: Interpretation of results, revision of the manuscript for important intellectual content, and approval of the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003e We thank the study participants and the German nystagmus network (Nystagmus Netzwerk e.V.) for their support.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eData is available upon request to the corresponding author.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eHamilton R, Bach M, Heinrich SP, \u003cem\u003eet al.\u003c/em\u003e ISCEV extended protocol for VEP methods of estimation of visual acuity. \u003cem\u003eDoc Ophthalmol\u003c/em\u003e. 2021;142:17\u0026ndash;24. doi: 10.1007/s10633-020-09780-1\u003c/li\u003e\n\u003cli\u003eHamilton R, Bach M, Heinrich SP, \u003cem\u003eet al.\u003c/em\u003e VEP estimation of visual acuity: a systematic review. \u003cem\u003eDoc Ophthalmol\u003c/em\u003e. 2021;142:25\u0026ndash;74. doi: 10.1007/s10633-020-09770-3\u003c/li\u003e\n\u003cli\u003eGopiswaminathan AV, Haldina J, Al-Nosairy KO, \u003cem\u003eet al.\u003c/em\u003e Objective Visual Acuity Estimates in Amblyopia Are More Accurate With Optotype-Based P300 Than With VEP Measurements. \u003cem\u003eTransl Vis Sci Technol\u003c/em\u003e. 2024;13:30. doi: 10.1167/tvst.13.12.30\u003c/li\u003e\n\u003cli\u003eWenner Y, Heinrich SP, Beisse C, \u003cem\u003eet al.\u003c/em\u003e Visual evoked potential-based acuity assessment: overestimation in amblyopia. \u003cem\u003eDoc Ophthalmol\u003c/em\u003e. 2014;128:191\u0026ndash;200. doi: 10.1007/s10633-014-9432-3\u003c/li\u003e\n\u003cli\u003eQuanz EV, Kuske J, Stolle FH, \u003cem\u003eet al.\u003c/em\u003e Effect of nystagmus on VEP-based objective visual acuity estimates. \u003cem\u003eSci Rep\u003c/em\u003e. 2024;14:16797. doi: 10.1038/s41598-024-66819-y\u003c/li\u003e\n\u003cli\u003eHoffmann MB, Seufert PS, Bach M. Simulated nystagmus suppresses pattern-reversal but not pattern-onset visual evoked potentials. \u003cem\u003eClin Neurophysiol\u003c/em\u003e. 2004;115:2659\u0026ndash;65. doi: 10.1016/j.clinph.2004.06.003\u003c/li\u003e\n\u003cli\u003eDunn MJ, Margrain TH, Woodhouse JM, \u003cem\u003eet al.\u003c/em\u003e Grating Visual Acuity in Infantile Nystagmus in the Absence of Image Motion. \u003cem\u003eInvestigative Ophthalmology \u0026amp; Visual Science\u003c/em\u003e. 2014;55:2682\u0026ndash;6. doi: 10.1167/iovs.13-13455\u003c/li\u003e\n\u003cli\u003eBach M. Visual Evoked Potentials \u0026ldquo;EP2000\u0026rdquo; \u0026ndash; Computer system by Michael Bach. 2007. https://michaelbach.de/sci/stim/ep2000/ (accessed 8 January 2025)\u003c/li\u003e\n\u003cli\u003eBach M, Maurer JP, Wolf ME. Visual evoked potential-based acuity assessment in normal vision, artificially degraded vision, and in patients. \u003cem\u003eBritish Journal of Ophthalmology\u003c/em\u003e. 2008;92:396\u0026ndash;403. doi: 10.1136/bjo.2007.130245\u003c/li\u003e\n\u003cli\u003eNorcia AM, Clarke M, Tyler CW. Digital Filtering and Robust Regression Techniques for Estimating Sensory Thresholds from the Evoked Potential. \u003cem\u003eIEEE Eng Med Biol Mag\u003c/em\u003e. 1985;4:26\u0026ndash;32. doi: 10.1109/MEMB.1985.5006224\u003c/li\u003e\n\u003cli\u003eNorcia AM, Tyler CW, Hamer RD, \u003cem\u003eet al.\u003c/em\u003e Measurement of spatial contrast sensitivity with the swept contrast VEP. \u003cem\u003eVision Research\u003c/em\u003e. 1989;29:627\u0026ndash;37. doi: 10.1016/0042-6989(89)90048-5\u003c/li\u003e\n\u003cli\u003eMeigen T, Bach M. On the statistical significance of electrophysiological steady-state responses. \u003cem\u003eDocumenta Ophthalmologica\u003c/em\u003e. 1999;98:207\u0026ndash;32. doi: 10.1023/A:1002097208337\u003c/li\u003e\n\u003cli\u003eBach M. The Freiburg Visual Acuity Test - Automatic Measurement of Visual Acuity: \u003cem\u003eOptometry and Vision Science\u003c/em\u003e. 1996;73:49\u0026ndash;53. doi: 10.1097/00006324-199601000-00008\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"documenta-ophthalmologica","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"doop","sideBox":"Learn more about [Documenta Ophthalmologica](http://link.springer.com/journal/10633)","snPcode":"10633","submissionUrl":"https://submission.nature.com/new-submission/10633/3","title":"Documenta Ophthalmologica","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"VEP, nystagmus, visual acuity, fixation instability","lastPublishedDoi":"10.21203/rs.3.rs-7205585/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7205585/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e\u003cp\u003eQuanz et al. (2024) reported that participants with nystagmus had higher objective visual evoked potential visual acuity estimates (VA\u003csub\u003eVEP\u003c/sub\u003e) by 0.12 logMAR relative compared to standard psychophysical VA (VA\u003csub\u003ePsych_Stat\u003c/sub\u003e). The cause of this modest, but significant VA\u003csub\u003eVEP\u003c/sub\u003e overestimation remains unclear. Here we investigated its association with the pattern-pulse stimulation mode applied for steady state VEP recording for VA\u003csub\u003eVEP\u003c/sub\u003e estimation. Specifically, we tested whether psychophysical visual acuity to pulsed optotypes (VA\u003csub\u003ePsych_Pulsed\u003c/sub\u003e) also exceeds standard optotype VA\u003csub\u003ePsych_Stat\u003c/sub\u003e.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eTwelve participants with nystagmus were included in this analysis. VA\u003csub\u003eVEP\u003c/sub\u003e was determined for pattern-pulse steady-state VEP stimulation (Quanz et al., 2024) using EP2000, psychophysical VA was determined to stationary (VA\u003csub\u003ePsych_Stat\u003c/sub\u003e) and to pulsed (VA\u003csub\u003ePsych_Pulsed\u003c/sub\u003e) Landolt-C optotypes employing a modified version of the Freiburg vision Test (FrACT). Pulsed stimulus timing was identical for VEP and VA (40 ms on and 93 ms off, i.e at 7.5 Hz). In a separate measurement, fixation stability within the central 4\u0026deg; was determined using microperimetry (Nidek MP-1), and the eye with the stronger fixation instability was selected for the analysis (12 eyes). LogMAR differences were assessed with a paired t-test and the correlation of fixation stability and VA differences (DVA\u003csub\u003ePsych\u003c/sub\u003e = VA\u003csub\u003ePsych_Pulsed\u003c/sub\u003e \u0026ndash; VA\u003csub\u003ePsych_Stat\u003c/sub\u003e) was tested.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eVA\u003csub\u003ePsych_Stat\u003c/sub\u003e (0.43\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06 logMAR) and VA\u003csub\u003ePsych_Pulsed\u003c/sub\u003e did not differ from each other (0.45\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06 logMAR, P\u0026thinsp;=\u0026thinsp;0.15), but from VA\u003csub\u003eVEP\u003c/sub\u003e (0.26\u0026thinsp;\u0026plusmn;\u0026thinsp;0.08 logMAR, P\u0026thinsp;=\u0026thinsp;0.02 and P\u0026thinsp;=\u0026thinsp;0.01, respectively). There was no correlation of DVA\u003csub\u003ePsych\u003c/sub\u003e with fixation instability (r\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.002, P\u0026thinsp;=\u0026thinsp;0.89).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003ePulsed stimulation appears not to be the reason for the VA\u003csub\u003eVEP\u003c/sub\u003e overestimation. Further research should address whether differences in the spatial stimulus properties might be of relevance, as VA\u003csub\u003ePsych\u003c/sub\u003e is tested with optotypes, VA\u003csub\u003eVEP\u003c/sub\u003e with extended patterns.\u003c/p\u003e","manuscriptTitle":"Impact of pulsed stimulation on objective and subjective visual acuity measurements in nystagmus","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-31 16:12:01","doi":"10.21203/rs.3.rs-7205585/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-08-28T21:52:24+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-08-26T11:42:42+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-08-21T19:29:24+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"54665499579945161619487879865489913735","date":"2025-08-04T13:35:18+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"131950822376837235670485371854268555534","date":"2025-07-31T02:44:59+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-07-28T09:45:18+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-07-26T12:23:48+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-07-26T12:23:13+00:00","index":"","fulltext":""},{"type":"submitted","content":"Documenta Ophthalmologica","date":"2025-07-24T12:13:05+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"documenta-ophthalmologica","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"doop","sideBox":"Learn more about [Documenta Ophthalmologica](http://link.springer.com/journal/10633)","snPcode":"10633","submissionUrl":"https://submission.nature.com/new-submission/10633/3","title":"Documenta Ophthalmologica","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"073ba3c5-3af6-4eb4-a067-6f463befd61b","owner":[],"postedDate":"July 31st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-11-10T16:00:12+00:00","versionOfRecord":{"articleIdentity":"rs-7205585","link":"https://doi.org/10.1007/s10633-025-10060-z","journal":{"identity":"documenta-ophthalmologica","isVorOnly":false,"title":"Documenta Ophthalmologica"},"publishedOn":"2025-11-04 15:57:18","publishedOnDateReadable":"November 4th, 2025"},"versionCreatedAt":"2025-07-31 16:12:01","video":"","vorDoi":"10.1007/s10633-025-10060-z","vorDoiUrl":"https://doi.org/10.1007/s10633-025-10060-z","workflowStages":[]},"version":"v1","identity":"rs-7205585","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7205585","identity":"rs-7205585","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}