To report a case of delayed orbital cellulitis with subperiosteal abscess after orbital floor fracture repair using an absorbable sheet implant (Macropore^®, Medtronic Inc., Minneapolis, MN, USA).

Case summary: A 16-year-old male visited the oculoplastic clinic for left eye pain, lower eyelid swelling and vertical diplopia for 1 day. The patient had a history of inferior orbital wall fracture repair surgery using Macropore^® 20 months prior. The orbital computed tomography scan showed a subperiosteal cystic mass with surrounding infiltration at the left orbital floor, and ethmoidal and maxillary sinusitis; however, sheet implant was not clearly observed. Despite systemic antibiotic treatment for 3 days, his clinical findings did not improve, thus we decided to drain the subperiosteal abscess through a transconjunctival approach. Intraoperatively, the Macropore^® sheet was almost dissolved, but small pieces remained. The culture of drained contents showed no microorganisms. Systemic antibiotics were continued for 18 days after surgery, and clinical symptoms completely improved.

Delayed orbital cellulitis should be considered in patients with extraocular muscle movement limitation and painful orbital swelling if the patient has a history of orbital wall fracture repair, even if a bioresorbable implant was used. Prompt imaging evaluation should be emphasized for early diagnosis and proper treatment.