Comparison of Aphakic Refraction and Biometry-Based Formulae for Secondary In-The-Bag and Sulcus-Implanted Intraocular Lens Power Estimation in Children

Abstract

Purpose: To compare the accuracy of refractive outcomes in children undergoing secondary in-the-bag or cilliary sulcus IOL implantation, using aphakic refraction (AR)-based formulae and biometry-based formulae. Methods: In this retrospective study, 39 eyes of the in-the-bag IOL group and the other 26 eyes of the sulcus-implanted IOL group. Holladay 1, Hoffer Q, SRK/T and SRK II formulae were employed depending on the biometric data, while Hug and Khan formulae were used based on preoperative aphakic refraction. The prediction error (PE) and the absolute value of predicted error (APE) were compared between the two groups and formulae. Results: In the in-the-bag IOL group, non-significant differences of APE were found among the 6 formulae, while the Holladay 1, Hoffer Q, SRK/T and SRK II all demonstrated a significant hyperopic shift of median PE value compared to the Hug formula and Holladay 1 and SRK II also showed a significant hyperopic shift of PE compared to the Khan . Higher percentages of eyes with PE less than 1 D were found using Hoffer Q and SRK/T. In the sulcus-implanted group, the Holladay 1, Hoffer Q and SRK/T had a significantly smaller median value of APE than the Hug and Khan formulae, and the SRK II had a significantly smaller median value of APE than the Hug formula, while Holladay 1 had the lowest value of APE. Higher percentages of eyes within PE less than 1 D were found using Holladay 1, Hoffer Q and SRK/T, while the highest was SRK/T. Significantly larger hyperopic shifts of median PE value using all the 6 formulae were found in eyes with sulcus-implanted IOL than with in-the-bag implanted IOL . In in-the-bag implanted IOL group, the Hug and Khan formulae had significantly smaller APE values when compared with the sulcus-implanted IOL group. Conclusions: whether IOL was in the bag or sulcus implantation, almost all the formulae showed hyperopic shift, SRK/T showed the best accuracy. Biometry-based formulae were superior to AR-based formulae in accuracy of IOL power calculation, especially when IOL was implanted in the sulcus. In-the-bag IOL implantation should always be with higher priorities, especially when using AR-based formulae in IOL power calculation.

Intraocular lens calculation using the ESCRS online calculator in pediatric eyes undergoing lens extraction

“…Others report lower predictability using the SRK/T formula as well, with a higher myopic shift, especially in young children, or short and normal eyes and lower amount of eyes within ±0.5 D from target refraction. [16][17][18][19][20][21][22] Others report a hyperopic shift for all of their tested formulas using second and third generation formulas, which is contrary to our results. 22 In previous studies, it was shown that in pediatric cataract surgery, the implantation of an IOL with posterior optic capture is the best alternative to prevent posterior capsule opacification.…”

“…[16][17][18][19][20][21][22] Others report a hyperopic shift for all of their tested formulas using second and third generation formulas, which is contrary to our results. 22 In previous studies, it was shown that in pediatric cataract surgery, the implantation of an IOL with posterior optic capture is the best alternative to prevent posterior capsule opacification. 23 However, this procedure could result in a change of the effective lens position, especially when the IOL is not implanted in-the-bag but in the sulcus.…”

“…Others report lower predictability using the SRK/T formula as well, with a higher myopic shift, especially in young children, or short and normal eyes and lower amount of eyes within ±0.5 D from target refraction. 16–22 Others report a hyperopic shift for all of their tested formulas using second and third generation formulas, which is contrary to our results. 22…”

“…16–22 Others report a hyperopic shift for all of their tested formulas using second and third generation formulas, which is contrary to our results. 22…”

“…23 However, this procedure could result in a change of the effective lens position, especially when the IOL is not implanted in-the-bag but in the sulcus. 21,22 In our study group, there was a large proportion of eyes with posterior optic capture (n = 41) with in-the-bag implantation. We could show that in eyes with intraoperative, posterior optic capture, the MedAE is lower in comparison with the nonoptic capture group, lowest in BU-II (0.53 D) followed by SRK/T (0.54 D) and EVO 2.0 (0.55 D, Table 2).…”