Patients frequently complain of visual changes after intraocular silicone oil injection. The degree of these changes as well as refractive changes were analyzed in 11 aphacic eyes that had a postoperative visual acuity of at least 0.1. Visual acuity and refraction were obtained with the patients in a supine position. Then multiple visual acuity tests were done and refraktion was measured up to 12 times a day with the patient sitting erect. All tests were done with a constant pupillary diameter. Mean differences of 3 D between the objective and subjective refraction were noted. In most eyes there was a shift of spherical equivalents towards hypermetropia after a change in posture from supine to erect. The mean shift was 3.4 D (range 0.75-6.25 D). Seven out of 11 patients showed an increase in visual acuity of up to 4 optotypelines within the first 4 h after changing to an erect position. Total eye examination and testing of best-corrected visual acuity were performed again between 4 weeks and 15 months after silicone oil removal (mean 9.6 months). On examination, all eyes had a totally attached retina; none developed secondary glaucoma. Ten out of 11 eyes did not attain a final visual acuity that was better than the best corrected visual acuity before silicone oil removal.