Comparison between two analysis systems of corneal topography

PURPOSE: To compare topographic features of patients with keratoconus between two systems: Orbscan IIz® (Bausch & Lomb, Rochester, New York, USA) and Wavetek Chroma®. METHODS: Twenty-nine patients that were diagnosed with keratoconus based on clinical and topographic characteristics were evaluated on their visit to Ophthalmology Hospital of Sorocaba in March 2010. Topographic variables, like maximum and minimum keratometric readings (Sim K) within 3 and 5 mm of central zone, and maximum keratometry, were analyzed by Orbscan IIz® and Wavetek Chroma®. RESULTS: A total of 58 eyes of 29 patients with keratoconus were enrolled in this study. Considering maximum keratometry, Orbscan IIz® registered 79.31% eyes whrereas Wavetek Chroma® 100%. Analysing maximum and minimum keratometric readings and average at 5mm of central zone occurred a statistically significant difference at the first parameter (95% confidence limits: -0.51 to -2.46, p=0.004), the keratometric reading by Orbscan IIz® was 46.91 (standard deviation: 2.92), whereas Wavetek Chroma® was 48,4 (standard deviation: 4.48). CONCLUSION: The new instrument Wavetek Chroma® could help to map topographically eyes with keratoconus which could not be measured using the Orbscan IIz® at maximum keratometry, minimum keratometric and average reading at 5 mm of central zone.

Cornea; Corneal diseases; Corneal topography; Keratoconus; Diagnostic techniques, ophthalmological

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