Background/aims To present a case series of patients with facial nerve palsy (FNP) undergoing lower eyelid surgery where inadequate horizontal tarsal length was encountered and managed with a periosteal flap.

Methods A two-centre retrospective, non-comparative case series of all patients with FNP who underwent lower eyelid periosteal flap procedures. Theatre records identified all such procedures performed by, or under the supervision of, one of two surgeons (RM, BCP) between November 2018 and November 2020. Outcome measures, including the Cornea, static Asymmetry, Dynamic function, Synkinesis grading score, were measured preoperatively and postoperatively.

Results All 17 patients had undergone medial canthal tendon (MCT) plication. Six had previously undergone MCT plication then were listed for further lower eyelid surgery. In 11 cases, horizontal deficiency was encountered intraoperatively, immediately following MCT plication. Four patients were surgery-naïve. 94% were within the ‘contraction phase’ of FNP (ie, greater than 1-year duration); eight (45%) had previously undergone lower eyelid shortening procedures (such as lateral tarsal strip procedure, LTS). All patients had improved lower eyelid position postoperatively, although at 1-year postoperation, four patients require redo lower eyelid surgery.

Conclusions MCT plication and stabilisation appear to be closely linked to the need for lower eyelid lengthening procedures, particularly in patients who have also undergone LTS and/or those within the ‘contraction phase’ of FNP. Unnecessary loss of horizontal tarsal length (particularly during LTS procedures) must be avoided in patients with FNP. Surgeons managing such patients should take care to identify inadvertent eyelid shortening early and be prepared to perform a lateral periosteal flap when required.