Background: For intraocular surgery, most authors recommend general anesthesia including intubation and neuromuscular blockade to avoid complications by patient movements. However, anesthesia using a laryngeal mask and avoidance of muscle relaxants is common clinical practice. Purpose of this prospective observational study was to compare the incidence of eye movement and deviation of the eye axis during general anesthesia adjusted to minimal alveolar concentration (MAC) for pars plana-vitrectomy (PPV) using a laryngeal mask without neuromuscular blockade (LM) versus endotracheal intubation and neuromuscular blockade (INT).
Methods: The patients (N.=148) who underwent PPV for vitreoretinal disorders received MAC adjusted general anesthesia by volatile anesthetics. Seventy-four patients were subjected to LM and 74 to INT. In both groups the patient's lungs were mechanically ventilated without allowing spontaneous ventilation. Eye movements and upward deviations were judged and documented during surgery. Postoperatively quality of immobilization was assessed by a standardized questionnaire.
Results: Intraoperative movements were not observed in either group. Upward eye deviation was observed in nine (12%) patients in the LM group, but not in patients in the INT group (0%; P=0.003). The standardized questionnaire revealed no clinically relevant difference in quality of immobilization between groups, especially eye deviations did not lead to any relevant surgical complications or difficulties.
Conclusions: For PPV, MAC adjusted balanced anesthesia using a laryngeal mask without neuromuscular blockade was associated with more, but clinically irrelevant upward eye deviations and may be an alternative to intubation with neuromuscular blockade. However, adequate depth of anesthesia must be assured to avoid unwanted injuries during surgery.