Abstract
Purpose :
Lens thickness (LT) is a biometric variable used in IOL power calculations. Our group previously elucidated an age-independent relationship between HgbA1C and LT. The aim of this study was to evaluate whether these blood glucose mediated LT changes have an impact on IOL power calculation accuracy among diabetics.
Methods :
A retrospective consecutive case series was assembled, containing 178 eyes of 178 patients that underwent cataract surgery with a monofocal / monofocal toric [enVista MX60E(T)] IOL. Refractions were performed 21-180 days after surgery. Diabetics had a HgbA1c reported within 3 months of preoperative biometry measurements. Lens constants for the Barrett Universal II (BU2) and Hill-RBF v3.0 were optimized such that the mean prediction error (MPE) was 0.00 D for the entire dataset, when LT was entered. The predicted post-operative spherical equivalent was calculated for each formula, with and without entering LT. Prediction errors were then compared for non-diabetic and diabetic groups.
Results :
Amongst non-diabetics (N = 136), the MPE was not impacted by omission or inclusion of LT with BU2 (paired difference = 0.008 +/- 0.07 D; p = .21) or Hill-RBF (paired difference = 0.001 +/- 0.04 D; p = .81). However, among diabetics (N = 42), MPE was impacted with BU2 (paired difference = 0.028 +/- 0.08 D; p = .02) but not Hill-RBF (paired difference = 0.001 +/- 0.06 D; p = .89). This finding was further accentuated in diabetics with HgbA1C > 7 (N = 21). The MPE with BU2 (without LT: 0.08 +/- 0.37 D; with LT: 0.12 +/- 0.35 D) and Hill-RBF (without LT: 0.11 +/- 0.39 D; with LT: 0.12 +/- 0.37 D) trended toward hyperopia when HgbA1C > 7, but this observation was not statistically significant.
Conclusions :
Amongst diabetics, blood glucose mediated changes in LT may have a small impact on the performance of both the BU2 and Hill-RBF v3.0 IOL power calculation formulas. Future work with larger sample sizes are needed to confirm these findings.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.