Purpose: To describe the differences in treatment costs for infants randomized to contact lens correction versus primary intraocular lens (IOL) implantation after unilateral cataract surgery in The Infant Aphakia Treatment Study. Design: Retrospective cost analysis of a prospective, randomized clinical trial based on Georgia Medicaid data and the actual costs of supplies used. Participants: The Infant Aphakia Treatment Study (IATS) is a randomized, multicenter (n=12) clinical trial comparing treatment of aphakia with a primary IOL or contact lens in 114 infants with unilateral congenital cataract. Intervention: Infants underwent cataract surgery with or without placement of an IOL. Main Outcome Measures: The mean cost of cataract surgery, and all additional surgeries, examinations, and supplies used up to 12 months of age. Results: The mean cost of treatment for a unilateral congenital cataract with primary IOL implantation was $14,752 versus $10,726 with contact lens correction. The initial cataract surgery accounted for approximately 50% of the treatment costs for both groups. Contact lens costs accounted for 15% ($1,600/patient) in the aphakic group whereas glasses costs only represented 4% ($535/patient) in the IOL group. The increased costs in the IOL group were primarily due to the higher cost of cataract surgery in this group ($7,302 vs. $5,357) and the cost of additional operations. Conclusions: For IATS patients up to 12 months of age, cataract surgery coupled with IOL implantation and spectacle correction was 37.5% (about $4000) more expensive than cataract surgery coupled with contact lens correction.