Objective: To evaluate the corneal topography and pachymetry in keratoconus.
Methods: Thirty-five patients (47 eyes) with keratoconus were evaluated by Orbscan corneal topography system. The location, anterior and posterior surface elevation, curvature and pachymetry were analyzed with special reference to the central point of cornea, the apex, the highest point of posterior surface, the point with greatest curvature and the thinnest point. The correlation between the point of greatest curvature and the apex was also analyzed.
Results: The mean elevation of the apex was (0.102 +/- 0.044) mm, the mean distance between the apex and the central point of cornea was (0.686 +/- 0.376) mm. Most of the apexes, the points with the highest posterior surface, the points with the greatest curvature were located in the inferior temporal quadrant, followed by inferior nasal, superior temporal and superior nasal quadrant. The SimK of keratocunus was (60.9 +/- 10.4/53.4 +/- 8.7) D and the mean powers within 3 mm and 5 mm were (57.1 +/- 8.0) D and (50.7 +/- 5.4) D respectively. High correlation between apex elevation and the apex curvature was found (r = 0.697, P < 0.01), and there was also negative relationship between apex elevation and corneal thickness (r = -0.563, P < 0.01).
Conclusions: The Orbscan system can provide accurate and subtle information about the shape and thickness of keratoconus, which can help us to learn this disorder deeply, especially in the early diagnosis of this disease.