Introduction <p>In advanced amyotrophic lateral sclerosis (ALS), eye movements often represent the last channel for intentional communication. While oculomotor function has traditionally been considered relatively preserved, emerging evidence indicates progressive impairment in long-term survivors on tracheostomy-invasive ventilation (TIV). As a result, eye-based communication may become increasingly unreliable before complete loss, challenging clinical decision-making and advance care planning (ACP).</p> Methods <p>We conducted a case-based topical review integrating clinical observation and literature to examine the trajectory of oculomotor decline, its impact on communication, and implications for treatment decisions. Three patients with ALS receiving TIV in a home-care setting illustrate key clinical and ethical challenges.</p> Results <p>Across cases and literature, oculomotor decline followed a gradual trajectory from effective eye-tracking communication to a complete locked-in syndrome. We identify a transitional phase of <i>communicative ambiguity</i>, in which residual ocular signals persist but can no longer be reliably attributed to intentional, patient-controlled communication. This phase is characterized by increasing inconsistency of signals and a divergence between observable responses and their interpretive certainty, creating uncertainty in assessing patient preferences.</p> Implications <p>Communicative ambiguity represents a clinically underrecognized but critical threshold in advanced ALS, marking the transition from direct patient autonomy to interpretative and surrogate-based decision-making. Failure to recognize this phase risks misinterpretation of patient intent and may undermine goal-concordant care. Timely and iterative ACP, initiated before communication becomes unreliable, is essential. We further propose four clinical pathways for treatment goal conversations, highlighting their differing implications for timing, symptom burden, and ethical decision-making.</p>