A 4-year-old boy with trisomy 21 and a congenital cataract underwent cataract extraction and implantation of an iris-supported intraocular lens (IOL). Four years later the implant dislocated anteriorly and had to be removed. Now, 11 years postoperatively, the eye is blind, painful and shrunken. IOL implantation in infants and children is theoretically justified to preserve vision, reduce amblyopia and preserve fusion. The use of modern posterior chamber IOLs, especially when implanted in the lens capsular bag (if technically feasible), could reduce the risk of complications. However, until further data are accumulated, a conservative approach is warranted.