Vertical D: a novel topographic pattern in some keratoconus suspects.
Ophthalmology
; 114(5): 1020-6, 2007 May.
Article
in En
| MEDLINE
| ID: mdl-17292474
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 OUTCOMEMEASURES:
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 microm and/or posterior corneal protrusion > 20 microm 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.
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Database:
MEDLINE
Main subject:
Cornea
/
Corneal Topography
/
Keratoconus
Type of study:
Etiology_studies
/
Observational_studies
/
Prevalence_studies
/
Risk_factors_studies
Limits:
Adult
/
Female
/
Humans
/
Male
/
Middle aged
Language:
En
Journal:
Ophthalmology
Year:
2007
Type:
Article
Affiliation country:
United States