Here we report a case of unexplained sudden visual loss after removal of silicone oil for rhegmatogenous retinal detachment repair. A patient with visual loss in one eye after removal of silicone oil was investigated with best-corrected Snellen visual acuity assessment, fundus biomicroscopy, optical coherence tomography, color fundus photograph, fluorescein angiography, electrophysiologic examination, automated perimetry, and visual evoked potentials. Best-corrected Snellen visual acuity was 20/30 while the silicone oil was in place. Visual acuity dropped dramatically to 20/200 after silicone oil removal. No other complications associated with oil removal were noted. The retina remained attached. Visual evoked potentials revealed decreased amplitude due to a damaged optic nerve, while the earliest central visual field defects disappeared unexpectedly almost 2 years after the last surgical procedure. No other abnormalities were demonstrated. Vision loss is a possible complication of silicone oil and removal. This case was distinguished by the permanent decrease of visual acuity despite the unexplained and quite complete recovery of the foveal threshold with no other relevant visual field defects.