Subjective visual perceptions during vitreoretinal surgery under local anaesthesia

To evaluate the visual experiences of patients during vitreoretinal surgery under local anaesthesia (LA).

Prospective questionnaire survey of 80 patients within 30 min of completion of vitreoretinal surgery under LA. Preoperative visual acuity, surgical procedure and its duration, efficacy of the local block, as well as intraoperative perceptions of flashes, colours, movements, and seeing instruments were documented.

A sub-Tenon's block was performed in 62/80 (77.5%) and a peribulbar block in the remainder. Overall, 72 (90%) of patients perceived light at some stage during their surgery. Of these, 51 (70.83%) observed movements, 45 (62.5%) saw colours, 38 (52.77%) saw instruments, and 24 (33.33%) saw flashes. The commonest observations were colourful swirls, black pipes, and the colour red. Most patients found these experiences pleasant or bearable; two found them frightening, and four would like to have been warned preoperatively about them. Preoperative visual acuity, diagnosis, gender of the patient, degree of akinesia, and the duration of surgery did not associate with visual perceptions. Logistic regression analysis showed that younger people were more likely to experience flashing lights (P=0.03) and to see instruments (P=0.04), patients having a sub-Tenon's block to perceive light (P=0.005), and those who did not receive awake sedation were more likely to see instruments (P=0.04).

Visual experiences are common during vitreoretinal surgery undertaken under LA. Where appropriate, patients should be forewarned about these experiences and reassured that they are not normally frightening.