Post laser vision correction (LVC) ectasia: a study enrolled by the Egyptian Society of Keratoconus and Corneal Transplants (ESKC&CT)

Session Details

Session Title: Keratoconus & Secondary Ectasia

Session Date/Time: Sunday 15/09/2019 | 08:00-10:00

Paper Time: 09:09

Venue: Free Paper Forum: Podium 2

First Author: : M.Fakhry Khattab EGYPT

Co Author(s): :    S. Eissa   K. AbdelAziz   T. El-Naggar   O. Said   A. Abdelatiff   M. Anis              

Abstract Details

Purpose:

Identify risk factors of corneal ectasia following LVC.

Setting:

A multicenter study; 8 centers across Egypt

Methods:

Retrospective cohort study involving 24 eyes with corneal ectasia occurrence between 2012 and 2017. 20 eyes after laser in situ keratomileusis (LASIK), 2 after photorefractive keratectomy (PRK), and 2 after femto small incision lenticule extraction (SMILE). All eyes were reviewed preoperatively and on ectasia diagnosis for Best Corrected Distant Visual acuity (BCDVA), manifest refraction, and Pentacam parameters including keratometric measurements, sagittal map patterns, corneal front and back surface elevations, point of thinnest corneal pachymetry, Belin/Ambrosio Deviation Display (BAD_D), and Ambrósio relational thickness maximum (ART max). Interval between surgery and ectasia diagnosis was reported for all eyes.

Results:

Preoperative means for sphere and cylinder were -4.1 Diopter(D), and -1.5 D respectively while after ectasia were -3.4 and -3.6 D respectively. Preoperative sagittal map patterns: 9 eyes Asymmetric Bowtie, 7 Symmetric Bowtie, 4 Crab claw, and 4 normal. For ectasia: 10 eyes central cone, 10 inferior steepening, and 4 crap claw. Treatment included corneal collagen cross linking (CXL) 16 eyes, CXL and intracorneal rings 3 eyes, and Deep anterior lamellar keratoplasty 5 eyes. Comparing interval till ectasia to age and thinnest pachymetry showed statistically significant negative correlation (r -0.432, p 0.035 and r -0.702, p<0.005 respectively).

Conclusions:

Sagittal map patterns, corneal thickness, BAD_D and ART max are important factors for ectasia prevention which has higher incidence following LASIK than PRK and femto SMILE. In our study, age affected the interval to ectasia .for LASIK, further analysis of percentage of tissue altered is needed by measuring stromal thickness before and after flap creation and following Excimer laser ablation.

Financial Disclosure:

None