High prediction errors for pediatric secondary IOLs

This retrospective study showed good overall refractive outcomes but significant prediction errors for secondary IOL implantation in children with aphakia following congenital cataract surgery.

The study’s authors analyzed the charts of 104 children (174 eyes) younger than 16 years of age who underwent secondary IOL implantation for aphakia. All of the children had previously undergone congenital cataract surgery. IOL power calculations were performed using the Sanders–Retzlaff–Kraff (SRK) II formula.

At three months, mean prediction error (PE) was 1.65 ± 2.46 D and mean absolute PE was 2.15 ± 1.68 D. Absolute PE was significantly less in eyes that underwent IOL power calculation with the IOL Master compared with eyes in which axial length measurements were performed under general anesthesia with the applanation method. Also, there was a significant inverse relationship between age at secondary IOL implantation and the mean absolute value of PE.

They note that although the goal of the surgery was to place the IOL in the capsular bag, in almost all eyes (172/174) they failed to open the capsular bag and clear the Soemmering's ring and the IOL was placed in the sulcus. This was attributed to nonstandardization of primary cataract surgery and a lack of planning regarding the desired size of the anterior and posterior capsular opening to facilitate reopening the capsular bag and in-the-bag IOL placement.

They offer the following recommendations for secondary IOL implantation:

• Perform the power calculation using the IOLMaster whenever possible;
• Compare axial length with aphakic refraction and also perform biometry of both eyes even in patients undergoing unilateral secondary IOL implantation;
• When implanting the IOL in the sulcus, ensure additional underpowering to counter the change in refraction due to change in IOL position;
• Place the secondary IOL in the bag by opening the bag and clearing the Soemmering's ring whenever possible.