Influence of pupil dilation on the Barrett Universal II (new generation), Haigis (4th generation), and SRK/T (3rd generation) intraocular lens calculation formulas: a retrospective study

Abstract

Background: We investigated the effect of pupil dilation on predicted postoperative refraction (PPR) and recommended intraocular lens (IOL) power calculated using three different generations of IOL power calculation formulas: Barrett Universal II (Barrett) (new generation), Haigis (4th generation), and SRK/T (3rd generation). Methods: This retrospective study included 150 eyes. All variables were measured and calculated using a ZEISS IOL Master 700. The following variables were measured before and after dilation: anterior chamber depth (ACD), lens thickness (LT), white-to-white (WTW). PPR and recommended IOL power were calculated by Barrett, Haigis, and SRK/T IOL calculation formulas. The change in each variable before and after dilation, and correlations between all changes were analyzed using the Wilcoxon signed-rank test and the Spearman’s rank-order correlation test, respectively. The influence of pupil dilation on recommended IOL power calculated by each formula was also analyzed. Results: The mean absolute change (MAC) in PPR before and after dilation was highest in Barrett, followed by Haigis and SRK/T. Significant differences were found among each MACs (P < 0.0001). Significant changes were observed before and after dilation in ACD and LT (P < 0.0001) but not in WTW. In Barrett and Haigis, there was a significant positive correlation between change in PPR and change in ACD (P < 0.0001) and a negative correlation between change in PPR and change in LT (P < 0.0001). Correlations were strongest in Barret followed by Haigis, especially in LT. Change in PPR in Barrett also demonstrated a significant positive correlation with change in WTW (P = 0.022). The recommended IOL power using Barrett and Haigis changed before and after dilation in 23.3% and 19.3% cases; SRK/T showed no change. Conclusions: In PPR and recommended IOL power, pupil dilation influenced Barrett most strongly, followed by Haigis and SRK/T. Given the stronger correlation between the change in PPR in Barrett and the change in ACD, LT, and WTW, the change of ACD, LT, and WTW is more important to the influence of dilation on Barrett. The influence of dilation on each formula and variable, including ACD, LT, and WTW, is key to improving IOL calculation.

Influence of Pilocarpine Eyedrops on the Ocular Biometric Parameters and Intraocular Lens Power Calculation

“…Te accuracy of those formulas under diferent clinical settings is diferent [41][42][43][44][45][46]. Te infuence of mydriatics on IOL power calculation has been reported elsewhere [47,48]. In the present study, we observed that the overall mean change in the IOL power calculation after the use of pilocarpine eyedrops was rather insignifcant both in PACG patients and normal subjects, with a relatively small portion of revealed an IOL power changes exceeding 0.25 D (see Table 4) which may have potential clinical relevance.…”