Vertical D. A Novel Topographic Pattern in Some Keratoconus Suspects

Juan Carlos Abad, Roy S. Rubinfeld, Maria Del Valle, Michael W Belin, Joseph M. Kurstin

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

Purpose: To describe a novel topographic curvature pattern, vertical D, which was present in some keratoconus suspects. This pattern was detected retrospectively in 2 patients who developed post-LASIK ectasia and prospectively in 4 patients who had other corneal abnormalities suggestive of keratoconus. Design: Retrospective interventional case series and prospective cross-sectional study. Participants: After vertical D topographic curvature patterns were noted in 2 patients (3 eyes) who developed post-LASIK ectasia, 1168 consecutive potential refractive surgical candidates (2336 eyes) evaluated at a refractive center were screened to detect this vertical D pattern. Methods: Placido disc-based curvature topography, ultrasound pachymetry, and elevation-based Scheimpflug topography were performed on these patients. Main Outcome Measures: Corneal curvature topographic patterns, central keratometry, inferior-superior and nasal-temporal ratios, skewed radial axis value, Humphrey Atlas PathFinder corneal analysis, corneal thickness, and corneal anterior and posterior elevation. Results: Four additional patients (7 eyes) with vertical D patterns were found (prevalence, 0.34%). In addition to this vertical D pattern, these patients had central corneal thickness < 500 μm and/or posterior corneal protrusion > 20 μm or positive results on keratoconus detection analyses. The 10 eyes with the vertical D pattern had more horizontal (nasal-temporal ratio) than vertical (inferior-superior ratio) curvature asymmetry: 0.98±0.04 diopters versus 0.44±0.2 diopters (paired t test, P<0.001). Conclusions: We propose that vertical D is a novel corneal curvature pattern reflecting horizontal asymmetry that was present in keratoconus suspect patients even if standard keratoconus analyses' results were negative.

Original languageEnglish (US)
JournalOphthalmology
Volume114
Issue number5
DOIs
Publication statusPublished - May 2007
Externally publishedYes

    Fingerprint

ASJC Scopus subject areas

  • Ophthalmology

Cite this