SSVEP-based visual acuity threshold estimation: linear extrapolation to noise level baseline with various noise...

Area of Science:

• Neuroscience
• Ophthalmology
• Biomedical Engineering

Background:

• Accurate visual acuity assessment is crucial for diagnosing and monitoring visual impairments.
• Steady-state visual evoked potentials (SSVEPs) offer an objective method for visual acuity testing.
• Optimizing the signal-to-noise ratio in SSVEP analysis is essential for reliable results.

Purpose of the Study:

• To investigate the impact of different noise definition criteria on the linear extrapolation technique for SSVEP-based visual acuity assessment.
• To identify the optimal noise definition criterion for improving the accuracy and reliability of objective visual acuity measurements.

Main Methods:

• Four distinct noise definition criteria were applied to calculate noise level baselines in the frequency domain.
• Electroencephalography (EEG) signals were recorded from subjects during resting state and visual stimulation.
• SSVEP visual acuity was estimated using a linear extrapolation technique, with performance evaluated against subjective visual acuity tests.

Main Results:

• Bland-Altman analysis revealed varying degrees of agreement between subjective and objective visual acuity measurements across the four noise criteria.
• Noise definition criterion 3, utilizing a broad frequency band excluding target and harmonic frequencies, showed the best performance with the smallest difference and tightest limits of agreement.
• This criterion yielded a difference of -0.0745 logMAR and a 95% limit of agreement of 0.2046 logMAR.

Conclusions:

• The choice of noise definition criterion significantly influences the accuracy of SSVEP-based visual acuity assessment.
• Noise definition criterion 3 is recommended for calculating the noise level baseline in linear extrapolation for SSVEP visual acuity estimation.
• This optimization can lead to more reliable and precise objective measurements of visual acuity.