Official ESCRS | European Society of Cataract & Refractive Surgeons
Lisbon 2017 Delegate Registration Programme Exhibition Virtual Exhibition Satellites OneWorld Travel Discount
escrs app advert

EVO: a new intraocular lens formula

Search Title by author or title

Session Details

Session Title: Cataract Surgery Outcomes: IOL Power Calculations

Session Date/Time: Sunday 08/10/2017 | 14:30-16:00

Paper Time: 15:48

Venue: Meeting Center Room I

First Author: : T.Yeo SINGAPORE

Co Author(s): :                        

Abstract Details


To evaluate and validate a new intraocular lens (IOL) formula, the EVO (Emmetropia Verifying Optical) formula, by comparing to existing IOL formulae.


Department of Ophthalmology, Tan Tock Seng Hospital, Singapore


817 eyes that underwent cataract surgery at Tan Tock Seng Hospital, Singapore were retrospectively analyzed. There were 471 ZCB00s, 190 Z9000s and 156 AAB00s. The EVO formula was compared to the Barrett Universal II (BUII), RBF, Haigis, Holladay I, SRK/T and Hoffer Q formulae. Lens constant optimization was performed separately for each IOL for Haigis, Holladay I, SRK/T and Hoffer Q. EVO, BUII and RBF used ULIB or recommended lens constants where available. The predicted refraction for each formula was subtracted from the post-operative refraction to obtain the error in prediction.


EVO had the lowest median absolute error (0.239) and mean absolute error (0.298), followed by BUII (0.250 and 0.302) and RBF (0.250 and 0.309). Median absolute errors for Haigis ULIB, Haigis triple-optimized, Haigis single-optimized, Holladay I, SRK/T and Hoffer Q were 0.251, 0.262, 0.276, 0.290, 0.289 and 0.285 respectively. Only EVO, BUII and RBF achieved more than 80% of patients with absolute prediction error of 0.5 or less. There was no statistical difference between EVO and BUII (p = 0.253). However, there were statistically significant differences between EVO and RBF (p = 0.025), and the remaining formulae (p < 0.001).


The EVO is a promising new formula that is comparable to BUII, and performs better than other IOL formulae.

Financial Disclosure:


Back to previous