Refractive shift of silicone oil tamponade in pseudophakic eye

BACKGROUND Refraction change of silicone oil (SO) tamponade in phakic and aphakic eye has been studied thoroughly; however, it is rarely studied in pseudophakic eye. In this paper we aimed to deduce a theoretical formula predicting refractive shift of silicone oil tamponade in pseudophakic eye and compared it with clinical findings. METHOD A theoretical formula was deduced through strict geometric optical principles under the Helmholtz Schematic eye model. Pre/postoperative refractive status of patients who previously underwent phacoemulsification, intraocular lens (IOL) implant, vitrectomy, SO tamponade and required SO extraction was studied. RESULTS Twenty-six patients (27 eyes, 13 males and 13 females) were studied. Refractive error of SO-off was -1.88 ± 2.73D, and of SO-in was 2.02 ± 3.90. Refractive shift of SO tamponade was -3.90 ± 1.74D. Refractive shift was significantly associated with refractive power of IOL (r = -0.7903, p < 0.0001, Pearson correlation test) and anterior chamber distance (ACD, r = 0.3840, p = 0.0480, Pearson correlation test). Theoretical refractive shift was -4.10 ± 1.51D, and there was no significant difference between the theoretical and the clinical refractive shift (p = 0.3329, Paired T test). CONCLUSIONS Refractive shift of SO tamponade in pseudophakic eye correlates with refractive power of implanted IOL and ACD, and strong correlation between theoretical formula and clinical findings was detected.