Refractive Growth of the Crystalline Lens in the Infant Aphakia Treatment Study.

Objective: To compare the rate of refractive growth (RRG3) of the crystalline lens ("lens") versus the eye excluding the lens ("globe") for the fellow, noncataractous eyes of participants in the Infant Aphakia Treatment Study. Design: Retrospective cohort study. Subjects: A total of 114 children who had unilateral cataract surgery as infants were recruited. Biometric and refraction data were obtained from the normal eyes at surgery and at 1, 5, and 10 years. Subjects were included if complete data (axial length [AL], corneal power, and refraction) were available at surgery and at 10 years of age. Methods: At surgery and at 1, 5, and 10 years, AL, corneal power, and cycloplegic refraction were measured in the normal eyes. For each eye, the RRG3 was defined by linear regression of refraction at the intraocular lens (IOL) plane against log10 (age + 0.6 years). The RRG3 for the globe was based on IOL power for emmetropia; the RRG3 for the lens was based on IOL power calculated to give the observed refractions. Intraocular lens powers were calculated with the Holladay 1 formula. The means were compared with a paired 2-tailed t test, and linear regression was used to look for a correlation between RRG3 of the lens globe. Main Outcome Measures: The RRG3 of the lens and globe. Results: Complete data were available for 107 normal eyes. The mean RRG3 of the lenses was -12.0 ± 2.5 diopters (D) and the mean RRG3 of the globes was -14.1 ± 2.7 D (P < 0.001). The RRG3 of the lens correlated with the RRG3 of the globe (R 2  = 0.25, P < 0.001). Conclusions: The RRG3 was 2 D more negative in globes compared with lenses in normal eyes. Globes with a greater rate of growth tended to have lenses with a greater rate of growth.

The contribution of intraocular lens calculation accuracy to the refractive error predicted at 10 years in the Infant Aphakia Treatment Study.

PURPOSE: To determine the relative contribution of intraocular lens (IOL) calculation accuracy and ocular growth variability to the long-term refractive error predicted following pediatric cataract surgery. METHODS: Pseudophakic eyes of children enrolled in the Infant Aphakia Treatment Study (IATS) were included in this study. Initial absolute prediction error (APE) and 10-year APE were calculated using the initial biometry, IOL parameters, postoperative refractions, and mean rate of refractive growth. The cohort was divided into children with a low-initial APE (≤1.0 D) and a high-initial APE ( >1.0 D). The 10-year APE was compared between the two groups using the Mann-Whitney U test. Linear regression was used to estimate the variability in prediction error explained by the initial IOL calculation accuracy. RESULTS: Forty-two children with IOL placement in infancy were included. Seventeen eyes had a low initial APE, and 25 eyes had a high initial APE. There was no significant difference in APE 10 years following surgery between individuals with a low initial APE (median, 2.67 D; IQR, 1.61-4.12 D) and a high initial APE (median, 3.45 D; IQR, 1.64-5.10 D) (P = 0.7). Initial prediction error could explain 12% of the variability in the prediction error 10 years following surgery. CONCLUSIONS: IOL calculation accuracy contributed minimally to the refractive error predicted 10 years after cataract surgery in the setting of high variability in the rate of refractive growth.

Effective lens position and pseudophakic refraction prediction error at 10½ years of age in the Infant Aphakia Treatment Study.

BACKGROUND: The refraction prediction error (PE) for infants with intraocular lens (IOL) implantation is large, possibly related to an effective lens position (ELP) that is different than in adult eyes. If these eyes still have nonadult ELPs as they age, this could result in persistently large PE. We aimed to determine whether ELP or biometry at age 10½ years correlated with PE in children enrolled in the Infant Aphakia Treatment Study (IATS). METHODS: We compared the measured refraction of eyes randomized to primary IOL implantation to the "predicted refraction" calculated by the Holladay 1 formula, based on biometry at age 10½ years. Eyes with incomplete data or IOL exchange were excluded. The PE (predicted - measured refraction) and absolute PE were calculated. Measured anterior chamber depth (ACD) was used to assess the effect of ELP on PE. Multiple regression analysis was performed on absolute PE versus axial length, corneal power, rate of refractive growth, refractive error, and best-corrected visual acuity. RESULTS: Forty-three eyes were included. The PE was 0.63 ± 1.68 D; median absolute PE, 0.85 D (IQR, 1.83 D). The median absolute PE was greater when the measured ACD was used to calculate predicted refraction instead of the standard A-constant (1.88 D [IQR, 1.72] D vs 0.85 D [IQR, 1.83], resp. [P = 0.03]). Absolute PE was not significantly correlated with any other parameter. CONCLUSIONS: Variations in ELP did not contribute significantly to PE 10 years after infant cataract surgery.

Refractive growth variability in the Infant Aphakia Treatment Study.

PURPOSE: Prediction of refraction after cataract surgery in children is limited by the variance in rate of refractive growth (RRG3). This study compared RRG3 in aphakic and pseudophakic eyes with their fellow, normal eyes in the Infant Aphakia Treatment Study. SETTING: Twelve clinical sites in the United States. DESIGN: Randomized clinical trial. METHODS: Infants randomized to unilateral cataract extraction had RRG3 calculated based on biometric data (axial length and keratometry) at cataract surgery and at 10 years of age, for both the normal and cataract eyes. Subjects were included if complete biometric data from both eyes were available both at surgery and at 10 years. Variance in RRG3 was compared between the groups with Pitman test for equality of variance between correlated samples. RESULTS: Longitudinal biometric data were available for 103 of the 114 patients enrolled. RRG3 was -15.00 diopters (D) (3.00 D) for normal eyes (reported as mean [SD]), -17.70 D (6.20 D) for aphakic eyes, and -16.70 D (6.20 D) for pseudophakic eyes (P < .0001 for comparison of variances in RRG3 between normal and all operated eyes). Further analysis found differences in the variance in axial length growth (P < .0001) between operated and normal eyes; the variance in keratometry measurement change did not reach significance. CONCLUSIONS: The standard deviation in the RRG3 of normal eyes in our study was half of that found in eyes that underwent cataract surgery.