To evaluate differences in central corneal thickness (CCT) before and after vitrectomy with injection of silicone oil as vitreous substitution material in order to determine whether silicone oil causes more frequent and/or pronounced corneal decompensation than other substitution materials.CCT was measured by ultrasonic pachometry in 42 eyes. 25 eyes received injection of silicone oil and 17 eyes C3F8, atmospheric air or saline. Measurements were performed 24 hours pre operatively, during anaesthesia pre operatively and 24 hours, 48 hours and five months post operatively.A progressive central corneal thickening could be demonstrated in both groups. Eyes which received silicone oil showed maximum CCT increase of 0.083 mm (14.1%) 48 hours post operatively. At follow-up CCT had decreased to baseline value in both groups. Silicone oil did not induce CCT changes that were significantly different from those induced by other substitution materials.Silicone oil injection in detachment surgery induces reversible corneal decompensation to the same degree as other substitution materials within the first five months post operatively.