Morphological variants in keratoconus: anatomical observation or aetiologically significant?
OBJECTIVE
Two morphological cone variants are identified in keratoconus; nipple and oval. The present study was designed to assess the impact of aetiological factors on cone morphology.


METHODS
As part of a prospective controlled study, keratoconic subjects from a suburban practice (n = 89) underwent videokeratograph examination and completed a questionnaire detailing aetiological factors.


RESULTS
Comparison of 95% confidence limits (CL; bootstrap method) for apical power between the two cone morphology groups showed no statistical significance. Oval cones were located at a greater eccentricity than nipple cones, as their definitions suggest. Associations between aetiological factors examined and the morphology of the cone were not significant (bootstrapped 95% CL).


CONCLUSIONS
Despite the suggestion of morphological variants in keratoconus, the results of the present study suggest a common cone aetiology.
Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia. j.armitage@optometry.unimelb.edu.au
J A
JA
Armitage
A S
AS
Bruce
A J
AJ
Phillips
R G
RG
Lindsay
D017668:Age of Onset; D003315:Cornea / Q000473:pathology* / Q000601:surgery; D019781:Corneal Topography; D006801:Humans; D007640:Keratoconus / Q000209:etiology / Q000473:pathology* / Q000601:surgery; D015948:Keratoplasty, Penetrating; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires