Intraoperative Pain Sensation During Cataract Surgery: Why Does Timing Matter?

Purpose: To investigate whether timing influences pain perception during cataract surgery and to investigate the possible mechanisms.Methods: Patients scheduled for cataract surgery both in the morning and afternoon were consecutively enrolled. Questionnaires to evaluate anxiety, including the Simplified State–Trait Anxiety Inventory, Amsterdam Preoperative Anxiety and Information Scale, and a visual analogue scale (VAS) for anxiety, were completed preoperatively, whereas a VAS for pain and the Wong–Baker FACES® Pain Rating Scale questionnaire were completed after surgery. Preoperative blood pressure and heart rate were recorded. Blood samples were acquired before surgery, and plasma cortisol, adrenocorticotropic hormone, adrenalin, and noradrenalin were tested.Results: Fifty-five patients underwent uneverntful cataract surgery (28 in the morning and 27 in the afternoon) were included in the final analysis. Greater intraoperative pain perception during cataract surgery was reported in the afternoon than in the morning. Overall anxiety levels were significantly higher in the afternoon. Plasma adrenalin levels were significantly higher in the afternoon. Cortisol levels were higher in the afternoon. Preoperative anxiety levels were closely related to intraoperative pain perception. Both adrenalin and cortisol correlated positively with preoperative anxiety, but only adrenalin correlated significantly with the pain scores.Conclusions: Patients undergoing cataract surgery in the afternoon showed more preoperative anxiety, which may have increased their relevant stress hormones. Both the patient’s emotional state and hormone levels may together aggravate his/her perceived pain in the afternoon. Monitoring preoperative anxiety levels, blood pressure, and heart rate should help to identify patients at higher risk of perceived intraoperative pain.Clinical trial registration:Trial registration number: NCT02182921Registration site: clinicaltrials.gov