Intraocular lenses are now a commonly accepted treatment for cataracts in older children and are used increasingly in younger children and infants. Intraocular lenses are superior to contact lenses in that they more closely replicate the optics of the crystalline lens, do not require daily ongoing care, and ensure at least a partial optical correction at all times. The simplicity and improved visual outcome of an intraocular lens correction may make caring for a child with a unilateral congenital cataract less stressful for parents. However, contact lenses remain the accepted treatment for children under 1 year of age due to concerns about the long-term safety of intraocular lenses and the potential for a large myopic shift developing in these eyes as they grow. Contact lenses provide excellent visual results in infants treated for bilateral congenital cataracts; however, two-thirds of infants treated with contact lenses for unilateral congenital cataracts remain legally blind in their aphakic eye. These poor visual outcomes are usually ascribed to competition from the sound eye and poor compliance with patching and contact lens wear regimens. Data from our pilot study and the literature suggest that superior visual results can be obtained if an intraocular lens is used to correct unilateral aphakia during infancy, but these eyes will experience more complications. Intraocular lenses will be increasingly implanted in infants regardless of whether or not we perform this trial. By performing this clinical trial, we can determine if the higher rate of complications with intraocular lenses is offset by improved visual outcome and decreased parenting stress.