Changes in anterior and posterior corneal curvatures in keratoconus
Section snippets
Subjects and methods
Clinical records of 46 eyes of 31 patients, ranging in age from 10 to 42 years (24.0 ± 6.9 years, mean ± standard deviation) with bilateral or unilateral keratoconus were retrospectively evaluated. The patients were previously diagnosed as having keratoconus in both eyes or in one eye on the basis of the clinical features, slit-lamp findings, and/or videokeratographic signs obtained with placido disk videokeratography (TMS-2, Computed Anatomy Inc., New York, NY). In 31 patients, 15 were tested
Results
For the anterior surface, significant differences were found among the three groups in spherical power (P < 0.0001, Kruskal Wallis test), regular astigmatism (P < 0.0001), and asymmetry (P < 0.0001), but not in higher order irregularity (P = 0.2046) (Table 1). Spherical power, regular astigmatism, and asymmetry in the clinically apparent keratoconus eyes were significantly larger than those of normal controls (P < 0.0001, respectively, Mann-Whitney U test). Spherical power, regular astigmatism,
Discussion
For the anterior surface, keratoconus eyes exhibited a significantly greater amount of spherical powers regular astigmatism, and asymmetry than the normal controls. Similarly, the anterior surface of the keratoconus suspect eyes had significantly greater spherical power and asymmetry than the normal controls. In general, the most specific topographic changes in the anterior corneal curvature of keratoconus are central steepening and protrusion of the cornea usually inferior to the visual axis.15
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The authors have no commercial or proprietary interest in the product or company described in the current article.