Using electroencephalogram spectral components to assess visual fatigue caused by sustained prism-induced diplopia

When the eyes were given maximum disparity, a good relationship was found between visual fatigue and the static or dynamic parameters of vergence and accommodation, as well as physiological signals and subjective evaluation value. The common experimental paradigm of asthenopia is to give the dynamic and repetitive stimulus. Therefore, the current research was proposed to devise a static and sustained stimulus of prism-induced diplopia and projected an experiment to induce visual fatigue by diplopia. Subjects put on the based-out prism whose degree could be adjusted by two pulleys on top of it, they wear their correctional glasses and adjusted slowly the degree of prism until the eyes were diplopia. This state should last for ten minutes in total, of which two minutes as a trial and had an intermediate rested for 30 seconds. The electroencephalogram (EEG) data and critical fusion frequency of 13 subjects were recorded for closed eyes before and after fatigue. In brain occipital, parietal, temporal and frontal lobe, ratio algorithms (α+θ)/β were significantly increased, while gravity frequency (GF) and power spectral entropy (PSE) were significantly reduced, and decline in the critical fusion frequency (CFF) also exists a significant difference. CFF also had a significant difference in the Spearman correlation with PSE, so EEG has a strong correlation with visual fatigue and EEG power spectral components might be a useful method to evaluate the degree of ocular fatigue.