Amyotrophic lateral sclerosis (ALS) is a rare neurodegenerative disease of the motor neuron system, characterised by progressive impairment of upper and lower motor neurons, while cognitive functions often remain intact. In advanced stages, patients may enter a Locked-In State (LIS), marked by near-total paralysis requiring assisted feeding, ventilation, and alternative communication systems based on residual movements, commonly eye motility. Still, as the patient transitions to the completely-locked-in state (CLIS), with total absence of skeletal muscle control, communication through conventional assistive devices, such as eye-trackers, becomes ineffective. Research has shown that the autonomic nervous system is largely spared in ALS, including the pupillary accommodative response (PAR), a physiological reflex that adjusts the pupil size according to changes in gaze depth.