Pain assessment in intensive care patients is a constant challenge. Approximately 50% to 80% of patients report pain at rest or during medical or nursing interventions (for example endotracheal suctioning, mobilization and rehabilitation, presence and care of invasive inputs, etc.). Obstacles to pain assessment and management are most often due to interference with communication due to impaired consciousness, airway support and connection to artificial pulmonary ventilation, or the effect of administered medication. Patients in intensive care are prone to delirium. Delirium can compromise patients' ability to verbalise pain for a variety of reasons (e.g. due to impaired attention, memory, thinking and language barriers). Also, pain and inadequate analgesia are risk factors for delirium. Pupillary reflex changes and their identification by automated pupillometry have yielded positive results regarding nociception assessment in adult and pediatric patients and in perioperative and postoperative care. At the same time, the response of these patients to opioid administration was investigated. The aim was to improve their analgesia. The aim of this study is to find out whether, there is an association between automated pupillometry and selected objective pain measurement scales in The Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) positive patients after surgery.