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Central Corneal Thickness Measurement by Ultrasound versus Orbscan II
1Ophthalmic Research Center, Labbafinejad Medical Center, Shahid Beheshti University MC, Tehran, Iran.
Purpose:
To compare Orbscan II and ultrasonic pachymetry for measurement of central corneal thickness (CCT) in eyes scheduled for keratorefractive surgery.
Methods:
CCT was measured using Orbscan II (Bausch & Lomb, USA) and then by ultrasonic pachymetry (Tomey SP-3000, Tomey Ltd, Japan) in 100 eyes of 100 patients with no history of ocular surgery scheduled for excimer laser refractive surgery.
Results:
Mean CCT was 544.7±35.5 (range 453-637) μm by ultrasonic pachymetry versus 546.9±41.6 (range 435-648) μm measured by Orbscan II applying an acoustic factor of 0.92 (P=0.14). The standard deviation of measurements was greater with Orbscan pachymetry but the difference was not statistically significant.
Conclusion:
CCT measurements by Orbscan II (applying an acoustic factor) and by ultrasonic pachymetry are not significantly different; however, when CCT readings by Orbscan II are in the lower range, it is advisable to recheck the measurements using ultrasonic pachymetry.
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