Lateral Canthal Position Following Lateral Orbitotomy and the Influence of Ocular Proptosis.

Purpose: Anecdotal evidence suggests that detachment of the lateral canthal tendon during lateral orbitotomy results in shortening of the horizontal palpebral aperture (HPA) and rounding of the lateral canthal angle (LCA). This study investigated the change in HPA and LCA following lateral orbitotomy and the effect of proptosis on the HPA. Methods: Retrospective, single surgeon, review of all cases undergoing lateral orbitotomy, comprising of a canthotomy and cantholysis and reconstruction of the lateral canthus using a single suture. The HPA and lateral canthal height (LCH) were measured on pre- and postoperative photographs using ImageJ software. Changes in the LCA and degree of proptosis were also investigated. Exclusion criteria included previous eyelid surgery, acute trauma, and less than 6 months' follow up. Results: There were 41 cases of lateral orbitotomy in 27 patients, 67% female, average age 51 years. Twenty patients had thyroid eye disease of which 14 underwent bilateral surgery; the other 7 patients had a variety of orbital pathologies. Thirteen patients underwent unilateral orbitotomy with the contralateral eye serving as a control. Average follow up was 23 months. Overall, the HPA and proptosis were reduced by 0.6 mm (p = 0.143) and 3.4 mm (p < 0.001), respectively. A 0.2-mm reduction in HPA was observed for every 1-mm reduction in proptosis. A difference in post-orbitotomy HPA was observed between cases and their matched controls (p = 0.016). No rounding of the LCA or significant change in LCH was observed following lateral orbitotomy. Conclusions: The described technique of lateral orbitotomy and simple reconstruction do not appear to cause lateral canthal drift or rounding. There was no significant change in HPA or LCH. The degree of change of proptosis does appear to influence the change of HPA.