*6.3.2.1 The critical flicker frequency (CFF)*

CFF test is a psychophysiological tool that studies the frequency at which a fused light (presented from 60 Hz downward) appears to be flickering to the observer. Similarly, the general arousal of the patient is measured. Earlier studies have shown a reduction in its performance with worsening cognition and improvement after therapy. The CFF test needs numerous trials, intact binocular vision, absence of red-green blindness, and specialized equipment [15]. CFF predicts the first episode of OHE in cirrhotic patients who had never experienced OHE, and predicts mortality risk [88]. CFF test has many advantages, for example, easy administration, application by a non-specialist personal, and results that are independent of numeracy, literacy, and age [89].
