Can VEP-based acuity estimates in one eye be improved by applying knowledge from the other eye?
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It is desirable to make VEP-based acuity estimates match standard subjective acuity numerically, as the latter is familiar to ophthalmologists and optometrists. This is achieved by applying an empirical conversion factor, and previous studies found the resulting values to be within ±1 octave of subjective acuity. This leaves room for improvement. In the present study, we tested for the case of a monocular acuity deficit whether the known difference between subjective and objective acuity in the trusted fellow eye can be used to get a more precise objective estimate in the eye of which the acuity is to be estimated. In other words, we tested whether it would make sense to determine a patient-specific conversion factor.
In 19 subjects, we obtained monocular objective and subjective acuity estimates with both eyes. Normal vision and artificially degraded vision were tested. Subjective acuity was taken as the veridical value. We computed the differences between objective and subjective acuity and reasoned that if these were correlated between eyes and acuity levels, the valid information from the trusted healthy eye could be used to improve the precision of the acuity estimate in the other, potentially impaired, eye.
The difference between objective and subjective acuity values was neither correlated significantly between eyes, nor was it correlated significantly between acuity levels.
Knowledge about the discrepancy between objective and subjective acuity values in one eye does not help improving the accuracy of acuity estimates in the other eye. The lack of a significant correlation between eyes even at the same acuity level suggests that a major part of the discrepancies between subjective acuity and VEP-based acuity is not the result of factors that would equally apply to both eyes, such as cortical morphology.
KeywordsVisual evoked potential Objective visual acuity Subjective visual acuity Contralateral eye Inter-ocular correlation Stimulus calibration
We are grateful to the study participants for their support.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Statement of human rights
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
Statement on the welfare of animals
This article does not contain any studies with animals performed by any of the authors.
Informed consent was obtained from all individual participants included in the study.
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