In patients affected by Complete Locked-In Syndrome (CLIS), all forms of voluntary communication are impaired due to total motor paralysis, despite preserved consciousness and cognitive abilities. In this context, conventional communication methods prove ineffective, highlighting the need for assistive devices that rely on residual physiological signals that can still be voluntarily modulated. The pupil accommodative response (PAR), which regulates pupil diameter based on the distance of the visual focal point, is typically preserved even in individuals with CLIS. This makes it a promising communication channel, as it can be voluntarily triggered by focusing gaze on visual targets positioned at different depths.