What we have learned from the Infant Aphakia Treatment Study: The 49th Annual Frank D. Costenbader Lecture.

Unilateral congenital cataracts lead to deprivation amblyopia, which can be severe. Until the 1970s, they were believed to be always associated with poor visual outcomes. However, advances in our understanding of the plasticity of the infant brain and the development of better surgical techniques allowed good visual outcomes to be obtained in a few of these patients. The Infant Aphakia Treatment Study (IATS) was conducted to provide empirical evidence regarding the best type of optical correction to be used following surgical extraction of the cataract. Specifically, infants were randomly assigned to either be left aphakic and to wear contact lenses or an intraocular lens (IOL) was implanted and the residual refractive error was corrected with spectacles. The study found that good visual acuity and stereopsis could be achieved in some patients in both treatment groups. Early cataract surgery, consistent optical correction and part-time patching of the fellow eye are important elements needed to achieve good visual outcomes. However, excess patching of the fellow eye may interfere with the development of stereopsis. More adverse events occurred after IOL implantation, particularly visual axis opacification, compared with the infants who were left aphakic. Glaucoma-related adverse events occurred in 40% of eyes after a 10-year follow-up and were not associated with IOL implantation. Further research is needed to increase the percentage of children with unilateral congenital cataracts who achieve good visual outcomes.