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C. Nguyen, R. Davis; Evaluation of Abnormal Orbscan Corneal Topography . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2558.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To evaluate corneal topographic parameters in patients who were declined refractive surgery using the Orbscan corneal topography system. Methods: 46 eyes of 23 patients who were declined laser in situ keratomileusis (LASIK) surgery (group 1) and 40 eyes of 20 normal patients as controls (group 2) were evaluated. Quantitative topographic parameters of the two groups were analyzed. Evaluation included astigmatism, thinnest pachymetry, max K, min K, and inferior apical displacement. Statistical analysis of the results was performed using Student’s t test. Results: 14 of 23 patients (60.9%) with abnormal corneal topography were contact lens wearers. In group 1, 6 of 23 patients (26.1%) were males and 17 of 23 patients (73.9%) were females. Abnormal topography results were repeated. The mean astigmatism was 0.79 (SD 0.36) D for group 1 and 1.28 (0.80) D for group 2. The thinnest point on the cornea had an average thickness of 518.68 (40.31) micrometers in group 1 and 531.70 (41.80) micrometers in group 2. The average max K was 44.80 (1.44) D for group 1 and 44.49 (1.86) D for group 2. The average min K was 44.00 (1.30) D in group 1 and 43.25 (1.72) D in group 2. The average inferior apical displacement was 6.55 (4.21) mm for group 1 and 2.00 (2.00) mm for group 2. Conclusions: The Orbscan corneal topography system is a useful tool to evaluate patients for refractive surgery. Quantitative topography parameters obtained from abnormal topography can provide a reference for comparisons between normal and abnormal topography. The observed difference in thinnest pachymetry and inferior apical displacement represents a trend, though not statistically significant. Larger sample size may be required in future studies to support the findings of this study.
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