Evaluation of mild, moderate, and advanced keratoconus using ultrasound pachometry and the eyesys videokeratoscope

WATTERS, GRANT A.; Owens, H.

Abstract

Background. The absolute accuracy of videokeratoscope (VKS) mapping of keratoconus is still in question, with contact lens-induced corneal warpage and chalazion having been shown to resemble this condition closely. Corneal thinning is investigated as a further aid to the diagnosis and description of keratoconus. Methods. The diagnosis of keratoconus in 41 individuals was verified by measuring the corneal thickness difference (I-S difference) between two disparate corneal locations, one inferior to (I) and one superior to (S) the corneal apex, using a Humphrey model 870 ultrasound pachometer. Corresponding measures of I-S radii were made using radius values obtained from the EyeSys VKS. Results. A comparison between I-S pachometry and I-S radius demonstrated a marginally increased sensitivity for the latter measurement. Using 95 % confidence levels from normative pachometric data, classification of severity of keratoconus is proposed as follows: (1) keratoconus suspect/early keratoconus: I-S pachometry 75 to 100 μm; (2) moderate keratoconus: 100 to 125 μm; and (3) advanced keratoconus: > 125 μm. Conclusion. I-S pachometry can be used as a descriptor of keratoconus.

• Journal Article Type: Article
• Acceptance Date: Sep 1, 1998
• Publication Date: Sep 1, 1998
• Journal: Optometry and Vision Science
• Print ISSN: 1040-5488
• Electronic ISSN: 1538-9235
• Publisher: Lippincott, Williams & Wilkins
• Peer Reviewed: Peer Reviewed
• Volume: 75
• Issue: 9
• Pages: 640-646
• DOI: https://doi.org/10.1097/00006324-199809000-00018
• Keywords: videokeratoscope mapping, VKS mapping, corneal thinning, corneal thickness difference
• Public URL: https://uwe-repository.worktribe.com/output/1099385
• Publisher URL: http://dx.doi.org/10.1097/00006324-199809000-00018