Official ESCRS | European Society of Cataract & Refractive Surgeons
Copenhagen 2016 Registration Programme Exhibitor Information Virtual Exhibition Satellite Meetings Glaucoma Day 2016 Hotel Star Alliance

10 - 14 Sept. 2016, Bella Center, Copenhagen, Denmark

This Meeting has been awarded 27 CME credits


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Comparison of accuracy of online formulas for IOL power calculation after myopic excimer surgery

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Session Details

Session Title: IOL Power Calculations

Session Date/Time: Sunday 11/09/2016 | 16:00-18:00

Paper Time: 17:44

Venue: Hall C2

First Author: : R.Chaudhuri INDIA

Co Author(s): :    R. Dutta   N. Shroff                 

Abstract Details


To compare the accuracy of various formulas provided by the ASCRS Post Keratorefractive Online Calculator for IOL power calculation in eyes with previous myopic excimer laser surgery.


Cataract & IOL Service, Shroff Eye Centre, A-9 Kailash Colony, New Delhi, India.


A retrospective analysis of 81 eyes of 63 patients with history of previous myopic LASIK/PRK undergoing cataract surgery with IOL implantation was done at least 6 months post-operatively. Nine formulas provided by the ASCRS Post- Keratorefractive Online Calculator were used: Adjusted Atlas-9000, Adjusted Atlas Ring, Masket Formula, Modified Masket, Barrett True-K, Wang-Koch-Maloney, Shammas, Haigis-L and Barrett True-K No History. The optimum IOL power corresponding to the target refraction was back-calculated using the stable post IOL implantation refraction and implanted IOL power. The optimum IOL power was compared with the IOL power predicted by each formula.


The mean age was 48.96±10.7 years. 61 eyes (75.3%) achieved a post-operative spherical equivalent of within ±1.00D. The mean logMAR UCVA was 0.16±0.14. On comparing predicted IOL power with optimum IOL power, the differences were not significant with Shammas (p=.983), Haigis-L (p=.116), Barrett No-History (p=.106) and Adjusted Atlas Ring (p=.064) formulas. The differences were significant with other formulas (p<.05). The Shammas and Haigis-L formulas gave the least prediction errors (0.004±0.95D and -0.40±1.23D respectively). The prediction error difference between Shammas and Haigis-L was significant (p=.006). The Shammas formula produced the highest percentage (80% eyes) within ±1.00D of optimum IOL power.


The “No History” formulas provided by the ASCRS Online Calculator are more accurate than those which rely on pre refractive surgery data. In this study, the Shammas and Haigis-L formulas gave the least prediction errors. The most accurate and predictable IOL power formula for eyes undergoing cataract surgery with previous myopic excimer correction was the Shammas formula.

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