Abstract
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. 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. 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.
Highlights
Visual acuity testing is one of the important tasks in ophthalmology and optometry practices
Average value from 12 measurements of visual acuity expressed with cpd using the sweep visual evoked potentials (sVEP) method in group 1 was 19.37+/-7.23 cpd
The current study showed a CI of +/-0.31 logarithm of minimal angle of resolution (logMAR) standard deviation (SD) of 0.16 in repeated measurements with sVEP in sample 2 and +/-0.11 logMAR in sample 1
Summary
Visual acuity testing is one of the important tasks in ophthalmology and optometry practices. In the case of preverbal or infantile children, it is better to use an objective method for visual acuity evaluation instead of a subjective method. In these cases, professionals can use an electrophysiological method with visual evoked potential modification for visual acuity determination. Today it is possible to measure two types of visual acuity with the sVEP method – distinguishing (stripes) and coincidence, Vernier visual acuity. Tyler et al.[2] showed that sVEP measurements are possible to compare with psychophysical examination of visual acuity, if it is used with proper distinguishing and luminance of testing display
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