Long-term results of the compatibility of a coralline hydroxyapatite implant as eye replacement

Coralline hydroxyapatite has been used since 1983 as volume replacement. Through 2001, a total of 200 hydroxyapatite implants were used in our department. This prospective study was undertaken to measure the subjective and objective long-term tolerance of this implant. In 2012, a total of 20 patients were examined, who were enucleated or eviscerated between 1993 and 2001 (average follow-up 16.2 years) and had an hydroxyapatite implant placed with a scleral sheath. We evaluated the subjective tolerance and measured the motility, the prominence of the globe, lid positions, changes of the conjunctiva and postoperative complications. The subjective long-term tolerance was reported to be good. All patients had a ptosis; an ectropion was found in 50% of patients. In 40% of the patients additional surgery was performed. The motility was better in primary than in secondary placed implants. Volume replacement was successful in 10 patients, 9 patients had a retraction and 1 patient a prominent prosthesis. Hydroxyapatite implants with sclera sheathing were well tolerated and showed good motility on long-term follow-up over more than 16 years. Lid malpositions such as ptosis or ectropion are common but might be due to mechanical stress through the prosthesis and atrophy of the orbital fat.