Article
Early detection of keratokonus using the Orbscan Corneal Topography System
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Authors
Published: | September 22, 2004 |
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Outline
Text
Objective
To establish and test diagnostic criteria for early detection of keratokonus. Detection of keratokonus is important prior to refractive surgery.
Methods
This retrospective review comprised 116 eyes of 58 patients who were diagnosed with keratokonus in at least one eye. ORBSCAN II (Bausch & Lomb) corneal topography was evaluated for all 116 eyes. Keratokonus forme fruste was defined as eyes with a stable refraction and an unchanged visual acuity. For comparison we evaluated Orbscan corneal topography of 40 eyes of 20 healthy volunteers prospectively. We evaluated anterior and posterior elevation difference, the difference in keratometric power and the max. keratometric power within the central 7mm in all eyes.
Results
We found 18 keratokoni forme fruste within the keratokonus patients. Posterior difference in elevation within the central 7mm was found to be the best of all evaluated diagnostic criteria. 15 of 18 eyes with keratokonus forme fruste had a difference in elevation of ≥80mm. 35 of 40 healthy eyes had a difference in elevation of <80mm. This diagnostic criterium has a sensitivity of 83% and a specifity of 88%.
Conclusions
Early stages of keratokonus can be detected with good sensitivity and specifity using the Orbscan system.