Impact of extreme (flat and steep) keratometry on the safety and efficacy of small-incision lenticule extraction: a matched comparative study

Session Details

Session Title: Advanced Tools for Outcome Assessment

Session Date/Time: Tuesday 17/09/2019 | 08:30-10:30

Paper Time: 09:50

Venue: Free Paper Forum: Podium 4

First Author: : M.Dirisamer GERMANY

Co Author(s): :    F. Reinking   J. Siedlecki   N. Luft   S. Priglinger                    

Abstract Details

Purpose:

To determine the influence of extreme (flat and steep) baseline corneal keratometry on the safety and efficacy of small-incision lenticule extraction (SMILE).

Setting:

Department of Ophthalmology, Ludwig Maximilians-University Munich; SMILE Eyes Clinic Linz, Austria

Methods:

The databases were screened for eyes that had undergone myopic SMILE with markedly flat (39–41.9 D) or steep (47–49.9 D) preoperative corneal keratometry values. Both groups were matched to a cohort of eyes with regular keratometry (42–46.9 D) by preoperative mean refractive spherical equivalent, sphere, astigmatism, age, corrected distance visual acuity and surgical SMILE parameters (optical zone, cap thickness). Main outcome measures included target accuracy, safety and stability as well as corrected and uncorrected visual acuity. Postoperative changes in higher order aberrations (RMS HOA, spherical aberration, coma, and trefoil) were evaluated on Scheimpflug imaging.

Results:

A total of 63 eyes (21 each) were followed up for 9±6 months. Mean baseline keratometry was 41.3±0.7 (flat), 45.5±1.0 (regular) and 47.7±0.6 (steep) diopters (D; p<0.0001). Compared to the regular group, the flat and the steep cornea group resulted in a non-inferior percentage of eyes within 0.50 D of target (p=0.35), final uncorrected distance visual acuity (UDVA; p=0.95) and CDVA (0.24). Flat corneas however experienced a stronger induction of spherical aberration (p=0.001), while steep corneas showed higher coma postoperatively (p=0.03).

Conclusions:

Compared to eyes with regular corneal curvature, non-inferior outcomes of SMILE concerning predictability, safety, and efficacy can also be expected in eyes with steep (>47 D) or flat (<42 D) preoperative keratometry. SMILE however induces more spherical aberrations in eyes with flat, and more coma in eyes with steep corneas.

Financial Disclosure:

travel has been funded, fully or partially, by a company producing, developing or supplying the product or procedure presented