Comparison of artificial eye amplitudes with acrylic and hydroxyapatite spherical enucleation implants

Purpose: To compare artificial eye amplitudes in patients who randomly rece ived either a hydroxyapatite or an acrylic, scleral-covered spherical impla nt after enucleation. Design: Randomized, controlled trial. Participants: Thirty-four consecutive patients who underwent enucleation be cause of an intraocular melanoma and 21 healthy control participants from t he hospital staff. Methods: Eligible patients randomly received a hydroxyapatite or an acrylic , scleral-covered spherical orbital implant. Fourteen patients were fitted with a hydroxyapatite implant, and 16 were fitted with an acrylic implant. We measured horizontal and vertical saccadic amplitudes of both the artific ial eye and the healthy eye. Measurements were performed with the magnetic search coils technique. Saccadic amplitudes of the artificial eye were comp ared with the healthy eye of the patient. The amplitudes of the healthy eye s were compared with saccadic amplitudes of control participants. The inter val from surgery to measurements was at least 3 months in all patients. Sac cadic gain (artificial eye and eye amplitude divided by target amplitude) a nd saccadic symmetry (artificial eye amplitude divided by healthy eye ampli tude) were calculated. Main Outcome Measures: Saccadic gain and saccadic symmetry. Results: The gain in the healthy eyes of the patients was comparable with t he gain of the control eyes. Saccadic symmetry was 1.0 in control participa nts. In patients, it was 0.334 in horizontal saccades and 0.577 in vertical saccades. However, saccadic symmetry did not differ significantly between the acrylic group and the hydroxyapatite group (P > 0.1 for any saccadic di rection). Equivalence was detectable with a power more than 90% for horizon tal saccades and more than 80% for vertical saccades. Curvilinearity was re jected for both patient groups and for all saccadic directions (P > 0.5). Conclusions: When no motility peg is placed, acrylic and hydroxyapatite sph erical implants yield comparable saccadic amplitudes of the artificial eye. Artificial eye amplitudes were markedly more restricted horizontally than vertically. In all saccadic directions, the relation between target amplitu de and artificial eye amplitude was linear. Ophthalmology 2000;107:1889-189 4 (C) 2000 by the American Academy of Ophthalmology.