Prediction Error Lower With In-The-Bag Secondary IOL Than Ciliary Sulcus IOL

In pediatric eyes, secondary in-the-bag intraocular lens (IOL) implantation achieved better prediction accuracy of IOL power calculation than ciliary sulcus implantation, according to a study published in the American Journal of Ophthalmology. The study also shows the adjustment of IOL power for ciliary sulcus IOLs required to reduce prediction error (PE).

Researchers conducted a prospective, nonrandomized, interventional study to compare the effects of secondary in-the-bag versus ciliary sulcus IOL implantation on the accuracy of IOL power calculation in pediatric eyes.

The study included pediatric patients with aphakic eyes who underwent either in-the-bag or ciliary sulcus secondary IOL implantation. The outcome measures included mean PE, mean absolute error, and percentages of eyes with PE within ±0.25 diopter (D), ±0.50D, ± 0.75 D, and ± 1.00 D were calculated and compared using SRK/T formula.

A total of 298 eyes of 183 patients (mean age, 47.85±18.57 months; 65% boys, 35% girls) were included in the study, 114 received in-the-bag IOL implantation (capsular group) and 184 underwent ciliary sulcus IOL implantation (sulcus group). Bilateral and unilateral cataract was present in 94% and 6% of the capsular group, respectively, and 86% and 14% of the sulcus group.

The researchers found the capsular group had a significantly lower mean absolute error and higher percentage of eyes within ±0.50 D of means PE than the sulcus group (mean absolute error, 0.90 vs 1.56 D; P <.001; eyes with ±0.50 D, 40.40% vs 14.29%; P <.001). 

Using multivariate analysis, the team discovered eyes were prone to maintain hyperopia (PE>0) if they received in-the-bag IOL implantation (β, -1.060; 95 confidence interval [CI]; -1.415-0.705; P <.001), were unilateral (β, 0.647; 95 CI, 0.144-1.150; P =.012) or had deeper anterior chamber depth (β, 0.362; 95 CI, 0.068-0.656; P =.016). 

The researchers estimate that when the predicted capsular IOL power is between 11.50 and 30.00 D, the power of a sulcus implanted IOL should be reduced by 0.50 to 2.50 D.

“In this large, prospective longitudinal case series study, the four-year follow-up data demonstrated that compared to ciliary sulcus secondary IOL implantation, in-the-bag IOL implantation yielded smaller PE. An appropriate IOL power adjustment for ciliary sulcus secondary IOL implantation should be made to counter the change in PE,” the researchers explain.

The primary limitation of the study was adjustment of the IOL power calculated for in-the-bag implantation with a formula that does not require phakic anterior chamber depth and lens thickness.