Posters

Tecnis Symfony IOL in eyes with prior laser refractive surgery: accuracy of IOL power estimation

Poster Details

First Author: A.Reddy UK

Co Author(s):    G. Macintosh   R. Fyfe   M. Wevill              

Abstract Details

Purpose:

Intraocular lens (IOL) Implants such as Tecnis Symphony are becoming increasingly popular choice due to the extended range of vision (EROV) they provide. Corneal power estimation in eyes with previous laser refractive surgery is fraught with difficulty and is major source of error in estimation of power of the IOL. Post-operative refractive surprise is often more challenging to treat in eyes that had previous laser refractive surgery. This study aims to assess the accuracy of estimation of power of Tecnis Symphony IOL in eyes with previous laser refractive surgery using the currently available formulae

Setting:

Private practice setting involving 3 surgeons in Aberdeen, Scotland practising at Kirkwood Fyfe Clinic and BMI Albyn Hospital

Methods:

Eyes with previous laser refractive surgery that underwent cataract surgery with implantation of Tecnis Symphony IOL were included in this prospective study. IOL Master biometry (IOL Master 500) was performed on all eyes. The built-in Haigis L formula on the IOL Master, the online ASCRS and Hill-RBF calculators were used to estimate the power of the Tecnis Symphony IOL for emmetropia. The surgeon customized A constant of 119.3 was used in all the calculations. Post-operative refractive outcome in the form of spherical equivalent (SE) at 6 weeks was compared with the predicted spherical equivalent to give the prediction error.

Results:

Eyes with pre-operative corneal astigmatism of more than 1 dioptre needing a toric Symphony IOL were excluded. Fourteen eyes had corneal laser refractive surgery for hyperopia and eight eyes for myopia. The mean and median absolute error (MAE), 95% confidence interval of MAE, mean and median prediction error and the standard deviation of the prediction error was calculation for each of the IOL calculation formulae used. Percentage of refractions within +/-0.5 dioptre and +/-1 dioptre of predicted spherical equivalent was assessed. A wide variation was noted in the predicted IOL power for emmetropia across the formulae used.

Conclusions:

A wide variation was noted in the predicted IOL power for emmetropia with the formulae used. Patients with previous laser refractive surgery should be counselled about the risk of refractive surprise when implanting the Tecnis Symphony IOL.

Financial Disclosure:

None