Effect of anterior chamber depth on the choice of intraocular lens calculation formula

Abstract

PurposeTo investigate the effect of anterior chamber depth (ACD) on the refractive outcomes of the SRK/T, Holladay 1, Hoffer Q and Haigis formulae in short, normal, long and extremely long eyes.MethodsThis retrospective study involved patients who had uncomplicated cataract surgery. Preoperative axial length (AL) was divided into four subgroups: short (< 22.00 mm), normal (22.00–24.49 mm), long (24.50–25.99 mm), extremely long (≥ 26.00 mm). Preoperative ACD was divided into three subgroups: < 2.5, 2.50–3.49, and ≥ 3.5 mm. Median absolute errors (MedAEs) predicted by the SRK/T, Holladay 1, Hoffer Q and Haigis formulae were compared with the Friedman test. Post-hoc analysis involved the Wilcoxon signed rank test with a Bonferroni adjustment. Correlations between ACD and the predictive refractive errors of the four formulas were analyzed.ResultsIn short eyes with an ACD < 2.5 mm, the Haigis formula revealed the highest MedAE. The difference in MedAE with the Hoffer Q formula (which had the lowest MedAE) was statistically significant (P = 0.002). In normal eyes, the Haigis formula significantly differed from the Holladay 1 (P = 0.002) and Hoffer Q (P = 0.005) formulae in the ACD < 2.5 mm group. In long eyes and extremely long eyes with an ACD ≥ 3.5 mm, the differences in MedAEs were statistically significant (P = 0.018, P = 0.001, respectively) and the Haigis formula had the lowest MedAEs in both subgroups (0.29 D, 0.30 D, respectively). In the total of 1,123 eyes, refractive errors predicted by the Haigis formula showed a significant negative correlation with the ACD (R2 = 0.002, P = 0.047).ConclusionsThe Hoffer Q formula is preferred over other formulae in short eyes with an ACD shallower than 2.5 mm. In short and normal eyes with an ACD < 2.5 mm the Haigis formula might underestimate ELP. The Haigis formula is the preferred choice in eyes with an AL ≥ 24.5 mm and an ACD ≥ 3.5 mm.

<p>Effect of anterior chamber depth on predictive accuracy of seven intraocular lens formulas in eyes with axial length less than 22 mm</p>

“…The mean RPE of all formulas was close to emmetropia except for Barrett Universal II which erred toward slight hyperopia. In the studies by Eom et al3 (ACD greater than 2.4 mm group) and Yang et al16 (ACD between 2.5 and 3.5 mm group), none of the formulas was statistically superior over the others. In our study, as the Haigis formula had the least MAE and MedAE and the highest percentage of eyes within RPE of ±0.50 D, we recommend it over other formulas in ACD Group 2.…”

“…The mean RPE of the Barrett Universal II and Haigis formulas was close to emmetropia, whereas that of the Hoffer Q, Holladay 1, Holladay 2, RBF Method, and SRK/T formulas erred toward slight overcorrection; that is, the outcome was slightly more myopic than what was intended. Eom et al3 in their study of 75 short eyes concluded that the Haigis formula was more accurate in the ACD less than 2.4 mm group, while Yang et al16 in their study of 90 short eyes found the Haigis formula performing worst in the ACD less than 2.5 mm group. In our study, as the Haigis formula had the highest MedAE and lowest percentage of eyes within RPE of ±0.25 D and ±0.50 D, we also do not recommend the Haigis formula in Group 1.…”

“…Preoperative ACD plays a pivotal role in determining the ELP. The predictive accuracy of different IOL power calculation formulas varies not only according to AL but also according to ACD 16. When preoperative ACD is considered in short eyes, then the margin of error in the predictive accuracy of different IOL formulas narrows down still further.…”

“…When preoperative ACD is considered in short eyes, then the margin of error in the predictive accuracy of different IOL formulas narrows down still further. Previous studies have reported the influence of ACD in short eyes considering various third and fourth-generation formulas 3,16. But none of them has utilized modern formulas like Barrett Universal II, Holladay 2, and the RBF Method.…”

Accuracy of intraocular lens power calculation formulas using a swept-source optical biometer

“…When cataract surgeons select the IOL power during cataract surgery, they mainly use the preferred formula such as the Hoffer Q or SRK/T because modern IOL formulas have similar accuracy in eyes with a normal range. [6,28] However, surgeons should cross-check different IOL formulas in eyes with an unusual range of ocular dimensions such as a short or long AL, flat or steep cornea, or a recently shallow ACD. A swept-source optical biometer, the IOLMaster 700, integrated the various IOL formulas including the latest-generation Barrett IOL power calculation formula, and we can automatically apply these formulas and compare the predicted results without using a separate program.…”