Abstract
Purpose :
Although accuracy of different formulas for intraocular lens (IOL) power calculation has been extensively studied before, there are limited data on whether type of IOL has any effect on this accuracy. Thus, in this study we compared the accuracy of IOL power formulas for two different monofocal aspheric lenses (AcrySof SN60WF, Alcon and Tecnis ZCB00, Abbott Medical Optics).
Methods :
A retrospective study was performed on 373 eyes implanted with SN60WF lens and 184 eyes implanted with ZCB00 lens during uncomplicated cataract surgery. Only one eye of each patient was included. Patients with previous corneal injuries or surgeries, including refractive surgery, were excluded. The predicted results of 5 different formulas (Barrett Universal II, Holladay 2, SRK/T, Hoffer-Q, and Haigis) were compared to patients’ refraction at 1-3 months postoperatively. Accuracy of these formulas was compared between SN60WF and ZCB00 lenses for different axial lengths: <22.5mm (short), 22.5-25.5mm (medium), and >25.5mm (long). The percentage of eyes within 0.5 D from the predicted refraction (%±0.5 D) was compared between the two IOL’s.
Results :
In patients with medium axial length, there were no significant differences in %±0.5 D between SN60WF and ZCB00 lenses for different formulas. However, in patients with short or long axial lengths, the %±0.5 D was significantly lower in the ZCB00 group compared with the SN60WF group (all P<0.05). Although in the SN60WF group there were no statistically significant differences in %±0.5 D among different axial lengths for each formula, for ZCB00 lenses %±0.5 D was significantly lower for those with short or long axial lengths compared with medium axial length. For both lenses, Barrett Universal II formula had significantly higher %±0.5 D compared with other formulas for all axial lengths (Table 1).
Conclusions :
Type of IOL can affect the accuracy of IOL power formulas for eyes with short or long axial lengths. In such eyes, these formulas are more accurate for SN60WF lens compared with ZCB00 lens.
This is a 2020 ARVO Annual Meeting abstract.