Accuracy of refractive prediction using a modified Pentacam-axial length (PAL) algorithm in patients undergoing cataract surgery with history of previous laser refractive surgery

Session Details

Session Title: IOL Power Calculations

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

Paper Time: 16:18

Venue: Hall C2

First Author: : C.MacGregor UK

Co Author(s): :    V. Mas Tur   J. Chovancova   F. Jazayeri   R. Jayaswal           

Abstract Details

Purpose:

Accurate IOL power calculation in patients undergoing phacoemulsification after previous laser refractive surgery (LRS) is becoming increasingly important as the number of patients we encounter having had LRS is growing. These patients often have high expectations of cataract surgery but pre-LRS refraction is often not available. In our department we developed an algorithm to facilitate IOL power calculation in this patient group. We present a 6-year retrospective analysis to determine the accuracy of our PAL algorithm.

Setting:

Ophthalmology Department, Queen Alexandra Hospital, Portsmouth, PO6 3LY, United Kingdom

Methods:

6-year retrospective analysis of all patients under our care who underwent cataract surgery with a previous history of LRS. Our PAL algorithm calculated each predicted IOL power with SRK/T formula using Pentacam equivalent K-reading (EKR) combined with an axial length-approximate amount of LRS correction nomogram adjustment. The main outcome measure was to compare the predicted refractive outcome using our PAL algorithm versus the achieved actual refractive outcome. We considered our calculation to be “on target” if within +/- 0.5D. Where possible, we compared our IOL power prediction to the predicted value using the ASCRS post keratorefractive IOL power calculator.

Results:

Forty five eyes were identified as having had phacoemulsification following previous LRS. Eighty three percent of cases using the PAL algorithm had spherical equivalent (SE) within 0.5D of predicted value. Ninety seven percent of cases had SE within 1.00D of predicted value. Unaided visual acuity was better than 6/6 in 50% of cases, better than 6/9 in 70% of cases and 6/12 or worse in 30% of cases.

Conclusions:

The PAL algorithm compares favorably to the ASCRS calculator. It facilitates the IOL power calculation in cases where the refraction pre-LRS is not available. The PAL algorithm is effective and versatile for predicting IOL power calculation following LRS.

Financial Disclosure:

NONE