Post-LASIK ectasia: analysis of cases and accuracy of three risk scoring systems in predicting its occurence

Session Details

Session Title: Investigations and Complications Management

Session Date/Time: Tuesday 13/09/2016 | 13:30-15:15

Paper Time: 14:10

Venue: Hall C3

First Author: : C.Chan SINGAPORE

Co Author(s): :    A. Saad   M. Dagher   M. Qazi   D. Gatinel           

Abstract Details

Purpose:

To analyze cases of post-LASIK ectasia and identify its risk factors by evaluating the accuracy of the SCORE Analyser (Bausch & Lomb TechnoLas, Germany), Percent Tissue Altered(PTA) and Randleman Ectasia Risk Score System (ERSS) in predicting its occurrence.

Setting:

Multicenter study: The results were analysed and work done primarily in two centres: the Singapore National Eye Centre, Singapore and the Rothschild Foundation, Paris, France

Methods:

Previously unpublished post-LASIK ectasia cases were identified and retrospectively analyzed. Pre-operative Orbscan IIz topographies and raw examination files were examined and SCORE number generated from the SCORE Analyzer. Patient demographics, treated manifest refraction spherical equivalent (MRSE), minimum cornea thickness (CT), intended flap thickness (FT) and ablation depth (AD) were obtained, and residual stromal bed thickness (RSBT) calculated. From these, PTA and ERSS values were generated. In unilateral ectasia, the non-ectatic eye was also evaluated.

Results:

Ectasia was seen in 31 eyes of 22 patients. Mean age at LASIK was 29.6±6.1. In ectatic eyes, standard interpretation of pre-operative Orbscan topographies showed minor or no abnormalities. Mean MRSE, CT, FT, AD and RSBT were -4.93±1.82D, 524.1±34.4μm, 123.8.4±24.9μm, 80.0±30.1μm and 319±46.3μm respectively. SCORE number was positive in 20 eyes(64.5%), mean 0.7±1.7, PTA ≥40 in 15(48.4%), mean 38.8±7.3. Twenty eyes (64.5%) were classified moderate to high risk by ERSS (mean 3.7±2.3). In 11 non-ectatic eyes, SCORE was negative in 10(90.9%), mean -0.9±1.2, PTA<40 in 5(45.5%), mean 40.5±6.6 and ERSS low risk in 7(63.6%), mean 2.5±2.3.

Conclusions:

Abnormal preoperative topography remains the most important risk factor for post-LASIK ectasia. The SCORE Analyzer’s addition of elevation, thickness variation and tomography data to the Orbscan IIz’s Placido and slit-scanning-based topography system improves its sensitivity in predicting ectasia risk. ERSS tends to over-predict the risk, while further studies are required to validate PTA as a screening metric for ectasia.

Financial Disclosure:

... receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented, ... travel has been funded, fully or partially, by a competing company, ... travel has been funded, fully or partially, by a company producing, developing or supplying the product or procedure presented, ... research is funded, fully or partially, by a company producing, developing or supplying the product or procedure presented, ... receives non-monetary benefits from a competing company., ... receives non-monetary benefits from a company producing, developing or supplying the product or procedure presented., ... receives consulting fees, retainer, or contract payments from a competing company