Application of Orbscan corneal topography system in screening preclinical phase keratoconus

Objective To compare the clinical value of Orbscan corneal topography system and common computer-assisted corneal topography in screening preclinical phase keratoconus.Methods One thousand eight hundred and twenty-nine cases (3 652 eyes), who prepared to do excimer laser refractive surgery, were divided into two groups, experimental group and control group, according to different look up methods, and corneal contact lens were not allowed to wear for 2 weeks before the examination. Corneal topography was made by TomeⅢ corneal topography system at microcoria in control group, and was also detected by new branded Orbscan corneal topography system which was made by USA BAUSCH LOMB LIMITED at half dark surroundings in experimental group.Results Nineteen preclinical phase keratoconus were detected in experimental group(972 eyes),and the detectable rate was 1.95%; 18 preclinical phase keratoconus in control group(2 680 eyes), the detectable rate was 0.67%.There is significant difference between two groups’ detectable rate(P0.05).Conclusion Orbscan corneal topography system is an important look up method before excimer laser refractive surgery.