Factors influencing visual evoked potentials: a scoping review

Objectives The aim of this scoping review is to map and describe available scientific evidence regarding biological and environmental factors influencing visual evoked potentials (VEP) in healthy individuals. The review seeks to identify the scope of existing research, methodological approaches, analyzed variables, and gaps in the current literature. Review Questions (PCC) Population: Healthy individuals without diagnosed neurological or ophthalmological disorders. Concept: Anthropometric and environmental factors influencing VEP, including age, sex, eye dominance, nutritional status, alcohol consumption, and caffeine intake. Context: Clinical and experimental studies employing visual evoked potentials (VEP). The main review questions are: 1. Which biological and environmental factors have been investigated in relation to VEP outcomes in healthy individuals? 2. What methodological approaches and VEP parameters were used in these studies? 3. What gaps exist in the current literature on factors influencing VEP? Eligibility Criteria Inclusion criteria: Original research articles, reviews, and case reports; studies involving healthy individuals; English-language publications; full-text availability; studies analyzing VEP in relation to at least one predefined factor. Exclusion criteria: Non-human studies; studies involving participants with diagnosed diseases; lack of full-text access; non-English publications; duplicate publications or studies reporting the same clinical data. Search Strategy A comprehensive literature search was conducted using the following databases: PubMed (MEDLINE), ScienceDirect, The Cochrane Library, Web of Science, and Google Scholar. The search covered publications from 1 January 2005 to 2 January 2026. An initial search was conducted in August 2025, followed by an updated search in January 2026. Both Medical Subject Headings (MeSH) and free-text terms were used. Example search strategies included: “visual evoked potentials AND age”, “visual evoked potentials AND sex”, “visual evoked potentials AND left eye AND right eye”, “visual evoked potentials AND alcohol consumption”, “visual evoked potentials AND caffeine intake”, and “visual evoked potentials AND nutrition”. Additionally, snowballing was performed by screening reference lists of relevant review articles. Study Selection The study selection process followed the PRISMA-ScR guidelines. After removal of duplicates, titles and abstracts were screened for relevance. Full texts of potentially eligible studies were subsequently assessed based on the predefined inclusion and exclusion criteria. Reasons for exclusion at the full-text stage were documented, and the selection process was illustrated using a PRISMA-ScR flow diagram. Data Charting The review employed a descriptive and qualitative approach. Data charted from included studies comprised population characteristics, analyzed factors (age, sex, eye dominance, nutrition, alcohol and caffeine intake), VEP methodology, and reported outcomes. The charting process was iterative and adapted as necessary to the nature of the available evidence. Data Synthesis and Presentation Results will be synthesized descriptively and presented using narrative summaries, tables, and evidence mapping. No meta-analysis or quantitative effect estimation is planned. Reporting The scoping review will be reported in accordance with the PRISMA Extension for Scoping Reviews (PRISMA-ScR).