• Cataract/Anterior Segment, Pediatric Ophth/Strabismus

    Review of: Accuracy of a universal theoretical formula for power calculation in pediatric intraocular lens implantation

    Eppley S, Arnold B, Tadros D, et al. Journal of Cataract and Refractive Surgery, May 2021

    Predictive errors after pediatric IOL implantation remain highly variable. This retrospective case series study of patients seen at a US academic medical center compared the accuracy of the Barrett Universal II formula with the Holladay 2, Hoffer Q, and SRK/T in predicting postoperative refraction for pediatric IOL implantation.

    Study design

    The study included 64 children aged ≤16 years (64 eyes; mean 5.9 years) who underwent cataract extraction and IOL implantation during an 8-year period and had refraction assessed at 3–16 weeks following surgery. Prediction error (PE) was defined as the postoperative mean spherical equivalent minus the target refraction. Performance across covariables (e.g., keratometry, axial length) was assessed. The differences in absolute median PE were compared between the Barrett Universal II formula and each other formula.


    Of the formulas assessed, the Barrett Universal II formula had the lowest mean PE (−0.22 D) and median absolute PE (0.79 D), while the SRK/T formula had the greatest mean PE (−0.50 D). The Barrett Universal II formula predictions were stable across all variables, and the Holladay 2 formula performed similarly.


    The limitations of this study include a small sample size (as pediatric cataracts are rare), the retrospective chart review study design, and the potential lack of standardization of biometry measurements or refractive methods, given that 89% of the procedures were performed by a single surgeon. Some postoperative refractions might have been limited by patient age and/or cooperation level. Finally, outcomes were examined only in the postoperative period; longer-term myopic shifts and refractive errors were beyond the scope of the study.

    Clinical significance

    The Barrett Universal II formula had similar or superior performance to other cataract surgery formulas. Although PEs can be highly variable in pediatric populations, this study supports the Barrett Universal II formula as an option for lens power calculation in children, including patients with extreme biometric measurements.