Ocular motility: Hydroxyapatite vs. silicone ball implant, a direct comparison using identical surgical technique

Purpose: Many patients elect not to undergo a secondary peg procedure when hydroxyapatite (HA) orbital implants are utilized. This study attempts to objectively quantitate and compare any difference in ocular motility of a prosthesis in patients with hydroxyapatite and silicone (Si) ball baseball implants when identical surgical techniques are utilized as described by Frueh, Nunery, and Dutton, and when no secondary Peg procedures are performed. Methods: All enucleation patients's charts were reviewed between 1992 and 1996 yielding a study population of 84 patients who met inclusion criteria. All patients were contacted by phone or by letter. Twelve came to the office for photographs (7 HA, 5 silicone) in primary, up, down, left, and right gazes while wearing Kestenbaum spectacles. Photographic slides were then projected onto a screen, and using the projected grid of the Kestenbaum spectacles and the midpupil position as a reference, the motility of the prosthesis vs. the contralateral eye was expressed as a ratio for all four positions of gaze. Results: Results are as follows. Supraduction: HA=0.35±0.12, Si=0.20±0.05, p=0.02; Infraduction:HA=0.50±0.17, Si=0.34±0.22,p=0.22; Right gaze: HA=0.28±0.16, Si=0.20±0.12, p=0.70; Left gaze: HA=0.25±0.17, Si=0.36±0.09, p=0.97. Only upgaze showed any significant statistical difference between HA and Si implants, which may be due to the age difference (HA=46.9, Si=59.6) between the two groups. Conclusion: The anecdotal reports of superior ocular motility of hydroxyapatite implants over silicone ball implants are not supported in this study. Given the low number of patients in this study, further recruitment of patients is necessary to fully elucidate the ocular motility relationship between hydroxyapatite and silicone ball implants when secondary peg procedures are not utilized.