PURPOSE: To report outcomes of secondary intraocular lens (IOL) implantation in the Infant Aphakia Treatment Study (IATS) SETTING:: Multicenter clinical practice DESIGN:: Secondary analysis of patients enrolled in a randomized clinical trial METHODS:: Details regarding all secondary IOL surgeries conducted in children enrolled in the IATS were compiled. We evaluated visual outcomes, refractive outcomes, and adverse events at age 10 ½ years. Comparisons were made to eyes that remained aphakic and to eyes randomized to primary IOL placement. RESULTS: 55/57 patients randomized to aphakia with contact lens correction were seen for the 10 ½ year study visit; 24/55 eyes (44%) had secondary IOL surgery. Median age at IOL surgery was 5.4 years (range 1.7 to 10.3 years). Mean absolute prediction error was 1.0 ± 0.7D. At age 10 ½ years, the median log MAR VA was 0.9 (range 0.2 to 1.7), similar to VA in the 31 eyes still aphakic (0.8, range 0.1 to 2.9); the number of eyes with stable or improved VA scores between the 4 ½ and 10 ½ year study visits was also similar (78% secondary IOL eyes, 84% aphakic eyes). For eyes undergoing IOL implantation after the 4.5 year study visit (n=22), the mean refraction at age 10 ½ years was -3.2 ±2.7D (range -9.9D to 1.1D), compared to -5.5 ±6.6 D (n=53, range -26.5 to 3.0D) in eyes with primary IOL (p=0.03). CONCLUSIONS: Delayed IOL implantation allows a more predictable refractive outcome at age 10 ½ years, though the range of refractive error is still large.