Official ESCRS | European Society of Cataract & Refractive Surgeons


Accuracy of the Haigis and Barrett True-K formulae for intraocular lens power prediction after radial keratotomy

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Session Details

Session Title: Toric IOLs & Lens Power Calculations

Session Date/Time: Sunday 15/09/2019 | 08:00-10:00

Paper Time: 09:20

Venue: Free Paper Forum: Podium 3

First Author: : R.Tavares BRAZIL

Co Author(s): :    G. Ferreira   E. Ghanem   D. Borges   L. Silveira   R. Ghanem                 

Abstract Details


To compare the accuracy of intraocular lens (IOL) power calculation in patients with previous radial keratotomy (RK) using the fourth generation formulas Haigis and Barrett True-K (BTK)


Sadalla Amin Ghanem, Eye Hospital, Joinville, Santa Catarina, Brazil


Patients with previous RK who had a minimum follow-up of 1 month after cataract surgery were retrospectively analyzed in a consecutive case series. Preoperative data from IOL-Master 500 or 700 and the IOL power implanted in the correspondent eye were used to calculate the predicted spherical equivalent (SE) target. The predicted SE for each formula was subtracted from the last follow-up visit SE, resulting in the refractive prediction error (RPE). Primary outcomes were the comparison of mean absolute and arithmetic RPE and the percentage of eyes within ±0.50 and ±1.00 with both formulas.


One hundred and eight eyes from 69 patients were evaluated with a mean follow-up of 6.8 months (SD 4.85; 1.7 to 18). The Haigis formula had a mean arithmetic RPE of -0.29 ± 1.00 D, statistically higher than the BTK, -0.03 ± 0.96 D (p<0.001). The mean absolute RPE was 0.80 ± 0.67 and 0.74 ± 0.60 and percentage of eyes with RPE within ±0.50 D was 43.5% and 42.6% and within ±1.00 D was 66% and 76% with Haigis and BTK, respectively (all p>.05).


BTK formula provided higher accuracy for IOL power calculation in post RK eyes undergoing cataract surgery than the Haigis formula.

Financial Disclosure:


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