Official ESCRS | European Society of Cataract & Refractive Surgeons


Assessment of repeatability for corneal epithelial thickness measurement with spectral-domain optical coherence tomography in eyes of anomalous refractive status

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Session Details

Session Title: LASIK & PRK II

Session Date/Time: Monday 16/09/2019 | 14:00-16:00

Paper Time: 14:30

Venue: Free Paper Forum: Podium 3

First Author: : D.Chen CHINA

Co Author(s): :    N. Lu   S. Chen   Q. Wang                       

Abstract Details


To assess the repeatability of corneal epithelium (ET) thickness measurements with spectral-domain optical coherence tomography (SD-OCT; RTVue-XR, Optovue, Inc., Fremont, CA) in myopic, keratoconic eyes and corneas after Transepithelial Photorefractive Keratectomy (TPRK), small-incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK).


Refractive Surgery Center, Eye Hospital of Wenzhou Medical University, China.


A total of 352 eyes of 352 patients (75 myopic, 68 post-TPRK, 61 post-SMILE, 75 post-FS-LASIK, 20 mild and 53 advanced keratoconic eyes) were included. Postoperative patients were recruited at the third month after surgery. The ET data were recorded from pachymetric map measured using SD-OCT in the following four zones: (1) central-2mm region, (2) eight paracentral regions within 2-5mm diameter, (3) eight midperipheral regions within 5-7mm diameter, (4) eight peripheral regions within 7-9mm diameter. Three successive scans were performed and the repeatability coefficient (CR) and coefficient of variation (CoV) were computed to evaluate the repeatability.


For all zones up to 9-mm diameter, the CR and CoV for ET measurements ranged from, respectively, 2.47 to 4.49 μm and 1.7% to 3.5% for myopic eyes, 3.74 to 7.48 μm and 2.6% to 6.2% for post-TPRK corneas, 3.49 to 6.01 μm and 2.3% to 4.7% for post-SMILE corneas, 6.48 to 8.14 μm and 4.0% to 6.3% for post-FS-LASIK corneas, 3.77 to 7.98 μm and 2.5% to 6.2% for mild keratoconic eyes, 5.32 to 11.11 μm and 3.5% to 8.0% for advanced keratoconic eyes.


RTVue-XR SD-OCT showed excellent repeatability when measuring ET in myopic eyes. Corneas that underwent keratorefractive surgery may interfere with the ET measurements using SD-OCT device. Among postoperative participants, the ET measurement for post-SMILE eyes showed the highest repeatability, followed by the post-TPRK eyes. For keratoconic corneas, the repeatability varied with the severity of disease. Here, we advise caution when using SD-OCT to measure ET for screening of the corneal ectasia at early stage after surgery, as well as for the monitoring of KC progression.

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