title: Contribution of sVEP visual acuity testing in comparison with subjective visual acuity.
abstract: OBJECTIVE
  Visual acuity determination is an important task in ophthalmology and optometry practices. Visual acuity can be examined objectively or subjectively. The objective examination method, sVEP, allows for quick objective measurements of patient's visual acuity. Previous studies have not demonstrated the repeatability of this objective sVEP method. This study aims to evaluate the sVEP method and compare it to a subjective method.
  
  
  RESULTS
  The sample was divided into two groups. For the first group, visual acuity was measured with sVEP and Snellen methods on only one patient twelve times. In the second group, visual acuity was measured twice with sVEP followed twice with the Snellen method with Landolt's rings and logMAR modification on 32 non-pathological patients. Results showed significant differences between average values of visual acuity obtained with both methods (sVEP and Snellen) in both samples (T-test, P < 0.01; Wilcoxon test, P = 0.02 in second group). In the second group, significant correlations between repeated sVEP measurements (Spearman test, P < 0.05, r = 0.69) were found but no significant correlation between average sVEP measurement and average Snellen measurement (Spearman test, P > 0.05, r = 0.15) was found.
  
  
  CONCLUSIONS
  Objective measurement of visual acuity with sVEP is a valid and reliable method, but is recommended only when it is not possible to use a subjective method for measuring visual acuity, e.g. children, patients with mental retardation or simulating/dissimulating patients.
authors.affiliation: Department of Optometry and Orthoptics, Faculty of Medicine, Masaryk University, Brno and Department of Ophthalmology and Optometry, St. Anne's University Hospital in Brno, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Vesely
mesh_terms: D000328:Adult; D004566:Electrodes; D005074:Evoked Potentials, Visual / Q000502:physiology; D005260:Female; D006801:Humans; D008029:Lighting; D008297:Male; D014787:Vision Tests / Q000379:methods; D014792:Visual Acuity / Q000502:physiology*; D055815:Young Adult
keywords: ETDRS chart; Snellen chart; electrophysiological methods; visual acuity; visual evoked potentials