Abstract
Abstract: :
Purpose: There have been no detailed clinical studies of refractive changes with silicone oil instillation in pseudophakic eyes. We examined the refractive changes in pseudophakic eyes of patients with idiopathic macular hole treated with silicone oil injection. Methods: Retrospective observational case series. Twenty consecutive eyes of 19 macular hole patients who had undergone successful pars plana vitrectomy using silicone oil (1000 centistokes) tamponade from July 2001 through June 2003 were studied retrospectively. Lensectomy with intraocular lens (IOL) implantation was performed in each patient prior to vitreous surgery. Five biconvex type IOL models (i.e., CANONSTAAR AQ–110NV; AMO SI55NB, AMO SI40NB, AMO AR40e; and Alcon MA60BM) were used. After pars plana vitrectomy and fluid–air exchange, silicone oil was injected to replace the air completely. Macular hole closure was confirmed by optical coherence tomography, and silicone oil removal was performed. Manifest refractions before silicone oil filling, with silicone oil filling, and after silicone oil removal were performed by best spectacle correction based on retinoscopy. None of the eyes had visual acuity worse than 20/200 at any time. Results: In all of the eyes, silicone oil instillation produced a shift towards hyperopia There was a mean shift in spherical equivalents of +5.69 diopters (range +2.88D to +8.38D with a standard deviation of ±1.71D) in the 20 eyes, and this change in refraction was significant (p<0.0001, paired t–test). In contrast, silicone oil removal produced a shift towards myopia. There was a mean shift in spherical equivalents of –5.63 diopters (range –3.00D to –7.50D with a standard deviation of ±1.33D) after silicone oil removal (p<0.0001, paired t–test). The absolute value of the refractive shift showed a strong correlation with the posterior radius of the IOL (r2=0.699, p<0.0001). Conclusions: IOL models with steeper posterior convex curvature result in larger refractive deviations in patients scheduled for silicone oil instillation.
Keywords: vitreous • refraction • vitreoretinal surgery