Abstract
Purpose :
To compare the agreement between the pachymetry measurements taken intra-operatively during LASIK from the excimer laser built in optical low-coherence reflectometry (OLCR) device and post-operatively with Fourier-domain OCT.
Methods :
LASIK flaps were created with the VisuMax 500 MHz femtosecond laser (Carl Zeiss Meditec AG, Germany). Flap configurations included thickness of 110µm, 90 degree side cuts, 8.1 flap diameter, 90 degree superior hinge, 50 degree hinge angle, and 3.04 mm hinge thickness. Intraoperative flap thickness was measured with Wavelight EX500 (Alcon Laboratories Inc, Texas) built-in OLCR. During the 14th day follow-up examination, patient corneas, flap size, and architecture were evaluated with the RTVue Fourier-domain OCT (Optovue Inc, California). Post-operative central corneal flap thickness was compared to intra-operative measurements.
Results :
Analysis was conducted on 26 eyes of 16 patients. Mean flap thickness measured by OCLR (122.04±11.6µm) was significantly lower compared to mean flap thickness measured by OCT [127.60±7.9µm, (p=0.04)]. Average difference between measurement devices was 5.54±12.7µm. Flap thickness measurements were poorly correlated between the two devices (r=0.20). The 95% limits of agreement between the devices was 49.66µm.
Conclusions :
Flap thickness measurements made by OCLR were significantly lower and had poor agreement and correlation with measurements made by OCT.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.