Exposed hydroxyapatite orbital implants. Report of six cases.

Six patients with complications of primary or secondary hydroxyapatite implants were studied. Complications included socket infection and/or conjunctival dehiscence. Complications were detected during regular follow-up examinations, and various treatment approaches were used. The hydroxyapatite implant exposure occurred 4 to 6 weeks (mean, 4.5 weeks) after implantation. Three of the six implants were wrapped in preserved donor sclera before implantation. One of the implants showed wide exposure and chronic infection and was removed. In two cases, scleral patch grafts with a conjunctival pedicle graft were performed, resulting in successful coverage of the implant without further conjunctival dehiscence. In one of the patients, a Tenon's conjunctival flap was advanced to cover the defect, and was unsuccessful with the spicules of the hydroxyapatite eroding through the vascular flap after 1 month. Three of the patients demonstrate a persistent conjunctival epithelial defect. These three patients with chronically exposed hydroxyapatite have remained stable with follow-up intervals ranging from 8 to 12 months. Early exposure of hydroxyapatite orbital implants is a potential problem despite meticulous technique. Implant coverage is difficult, although chronic exposure seems to be tolerated often in the hydroxyapatite orbital implant without migration or extrusion.