Predictability of intraocular lens calculation and early refractive status: The infant aphakia treatment study

Objective: To report the accuracy of intraocular lens (IOL) power calculations and the early refractive status in pseudophakic eyes of infants in the Infant Aphakia Treatment Study. Methods: Eyes randomized to receive primary IOL implantation were targeted for a postoperative refraction of +8.0 diopters (D) for infants 28 to 48 days old at surgery and +6.0 D for those 49 days or older to younger than 7 months at surgery using the Holladay 1 formula. Refraction 1 month after surgery was converted to spherical equivalent, and prediction error (PE; defined as the calculated refraction minus the actual refraction) and absolute PE were calculated. Baseline eye and surgery characteristics and A-scan quality were analyzed to compare their effect on PE. Main Outcome Measures: Prediction error. Results: Fifty-six eyes underwent primary IOL implantation; 7 were excluded for lack of postoperative refraction (n=5) or incorrect technique in refraction (n=1) or biometry (n=1). Overall mean (SD) absolute PE was 1.8 (1.3) D and mean (SD) PE was +1.0(2.0) D. Absolute PE was less than 1 D in 41% of eyes but greater than 2 D in 41%of eyes. Mean IOL power implanted was 29.9D(range, 11.5-40.0 D); most eyes (88%) implanted with an IOL of 30.0 D or greater had less postoperative hyperopia than planned. Multivariate analysis revealed that only short axial length (<18 mm) was significant for higher PE. Conclusions: Short axial length correlates with higher PE after IOL placement in infants. Less hyperopia than anticipated occurs with axial lengths of less than 18mm or high-power IOLs. Application to Clinical Practice: Quality A-scans are essential and higher PE is common, with a tendency for less hyperopia than expected. Trial Registration: clinicaltrials.gov Identifier: NCT00212134