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C. R. Salaroli, Y. Li, J. L. B. Ramos, D. Huang; Repeatability of LASIK Flap Measurement with Fourier-Domain Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2009;50(13):589.
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To evaluate the repeatability of LASIK flap thickness measurement using Fourier-domain optical coherence tomography.
A Fourier-domain OCT system (RTVue, Optovue Inc., Fremont, CA) with a corneal adaptor module (CAM) was used to image the cornea. It operated at 0.8 µm wavelength and had a scan rate of 26,000 axial-scan/second. The axial resolution was 5 µm in tissue. LASIK flaps were created using a femtosecond laser (Pulsion; IntraLase Corp., Irvine, CA) with a 110-µm setting. Horizontal scans (6mm long, 1024 axial scan per frame) centered at the corneal vertex were obtained 1 week after the surgery. Sixteen consecutive frames were acquired for each scan and automatically registered and averaged to increase the signal to noise ratio. Two repeated scans were obtained for each eye. RTVue CAM software also automatically identified the anterior and posterior corneal boundaries. A manual flap computer caliper tool was used to measure the LASIK flap thickness at the center (0mm), ±0.5mm and ±1.0mm away from the center. The repeatability of the flap measurements was evaluated by pooled standard deviation (SD) of repeated measurements.
Seventeen eyes of 10 patients were scanned 1 week postoperatively. The flap thicknesses were 122.53 + 8.48 µm (0 mm), 120.53 + 9.07 µm (-0.5mm), 120.62 + 8.76 µm (+0.5mm), 119.29 + 6.62 µm (-1.0mm) and 120.35 + 8.27 µm (+1.0mm). The repeatability of flap measurement was 2.25 to 3.87 µm inside 2-mm diameter.
RTVue CAM Fourier-domain OCT was a noncontact, rapid, and repeatable system to measure LASIK flap thickness.
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