Session: Free papers Session IV - Eye muscle surgery

Safety and efficacy of squint surgery under sub-tenon’s local anaesthetic in adult cohort 

Introduction

This study of a single tertiary referral adult strabismus service aimed to assess the safety, efficacy and patient satisfaction of strabismus surgery performed under sub-tenon's local anaesthetic.



Methods

This is a retrospective cohort study of consecutive patients who had strabismus surgery under local anaesthetic from June 2021 to November 2023. Those without follow up data were excluded. Electronic patient record is used to extract demographics, procedure details and outcomes. Oculocardiac reflex (OCR) episodes were measured as a decrease in pulse rate of 20% compared from baseline. A subset of patients were asked to complete a patient satisfaction questionnaire to assess patient experience throughout the procedure.



Results

116 patients were included. There were 57 males and 59 females. The mean age was 59 years (21-89). Most underwent single muscle procedures including recessions, resections, transpositions of horizontal and vertical recti, and inferior oblique myectomies. 10 cases were 2 muscle procedures.



52 patients had hyalase (hyaluronidase) used in their sub-tenon's injection and 2 patients had oral benzodiazepine sedation.



There were no anaesthetic complications, particularly no OCR, all patients had pupil dilation post anaesthesia. There were no surgical complications and the intended outcome was achieved in 98 out of 116 cases (84%). Of the 18 patients for whom the intended outcome was not achieved, 8 have subsequently undergone further procedures and 4 requiring prism correction.



Of the respondents to the questionnaire,  93% of patient were very satisfied with intra-operative pain control. Patient returned to normal daily activities within 2.6 days (range 0-7 days). 



Conclusions

Local anaesthesia is safe and effective in our cohort of patients. There were no cases of OCR. We postulate the presence of pupil dilation after administration of sub-tenons indicates anaesthesia of the ciliary ganglion with blockage of the afferent arc of this reflex.