MORPHOLOGICAL VARIANTS IN KERATOCONUS - ANATOMICAL OBSERVATION OR ETIOLOGICALLY SIGNIFICANT

Purpose: 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 pros pective controlled study, keratoconic subjects from a suburban practic e (n = 89) underwent videokeratograph examination and completed a ques tionnaire detailing aetiological factors. Results: Comparison of 95% c onfidence limits (CL; bootstrap method) for apical power between the t wo cone morphology groups showed no statistical significance. Oval con es were located at a greater eccentricity than nipple cones, as their definitions suggest. Associations between aetiological factors examine d and the morphology of the cone were not significant (bootstrapped 95 % CL). Conclusion: Despite the suggestion of morphological variants in keratoconus, the results of the present study suggest a common cone a etiology.