5-year outcomes after primary intraocular lens implantation in children aged 2 years or younger with congenital or infantile cataract: findings from the IoLunder2 prospective inception cohort study

International initiatives to prevent childhood blindness have highlighted the importance of early, effective intervention for congenital and infantile cataract. In the UK, intraocular lens implantation has been widely adopted by surgeons to treat these conditions. However, evidence about the benefits and risks of this technique in different age groups is limited. The IoLunder2 study assessed outcomes following primary intraocular lens implantation in children aged 2 years and younger with congenital or infantile cataract.The IoLunder2 study was a prospective observational cohort study done at 31 sites in the UK and Ireland. Eligible children were aged 2 years or younger who had cataract surgery concurrently with intraocular lens implantation or conventional treatment (aphakic correction with contact lenses or glasses) after cataract surgery between Jan 1, 2009, and Dec 31, 2010. Children with significant ocular comorbidity precluding lens implantation, defined by the presence of complex persistent fetal vasculature, other ocular structural anomalies, severe microcornea (horizontal corneal diameter9·5 mm), or severe microphthalmos (axial length16 mm), were excluded from the analysis of the key outcomes. Postoperative visual rehabilitation was assessed at 1, 3, and 5 years after surgery with a 4m logarithm of the minimum angle of resolution (logMAR) notation test. Best corrected visual outcome (acuity) overall was assessed 5 years after surgery for children with bilateral and unilateral cataract. We also used multivariable logistic and linear regression to model the association between intraocular lens implantation and outcomes of interest (vision, glaucoma, and visual axis opacity).A total of 256 eligible children were recruited; two had incomplete data and were excluded. 158 of the 254 included children (102 [65%] with bilateral cataract and 56 [35%] with unilateral cataract) had no significant ocular morbidity and were analysed for the key outcomes. Primary intraocular lens implantation was done in 88 (56%) of 158 children (50 children with bilateral cataract and 38 children with unilateral cataract). 70 (44%) of 158 children had conventional treatment (52 with bilateral cataract and 18 with unilateral cataract). Overall median visual acuity at 5 years was 0·34 logMAR (IQR 0·20-0·54) for children with bilateral cataract and 0·70 logMAR (IQR 0·3-1·3) in the operated eye for children with unilateral cataract. Primary intraocular lens implantation was not associated with better visual outcome than conventional treatment in children with bilateral cataract (adjusted coefficient -0·1, 95% CI -0·5 to 0·3, p=0·48) or unilateral cataract (adjusted coefficient -0·3, -0·6 to 0·2, p=0·36), or reduced incidence of postoperative glaucoma in children with bilateral cataract (adjusted odds ratio [OR] 0·5, 0·10 to 1·80, p=0·28), but was associated with a five times higher risk of reoperation for visual axis opacity requiring general anaesthesia in children with bilateral cataract (adjusted OR 5·94, 95% CI 2·14-16·47, p=0·001) and a 20 times higher risk in children with unilateral cataract (20·15, 3·01-134·00, p=0·001).The findings of this cohort study indicate that intraocular lens implantation does not confer better vision or protection against postoperative glaucoma, and conversely increases the risk of requiring early reoperation in children younger than 2 years with bilateral or unilateral cataract. The routine use of intraocular lens implantation in this age group cannot be recommended.National Institute for Health Research, Ulverscroft Foundation, and the Academy of Medical Sciences.