Abstract
Purpose:
Forme fruste keratoconus (FFK) is defined as a cornea which has no abnormal findings by slit-lamp examinations and Placido-based corneal topography, and is the fellow eye of a patient with clinical keratoconus. FFK has recently gained a lot of attention because it is the borderline condition between keratoconus suspect and normal cornea. The purpose of this study was to compare the corneal shape and ocular aberrations of eyes with FFK to that of normal corneas.
Methods:
We studied 38 eyes with FFK and 50 eyes with normal corneas. The corneal thickness and location of thinnest point, Belin-Ambrósio enhanced ectasia Display (BAD) parameters, Df, Db, Dp, Dt, Da, and D, and corneal coma aberrations (anterior, posterior and total cornea) for a 4 mm diameter were obtained with a rotating Scheimpflug camera (Pentacam HR, OCULUS Optikgeräte GmbH, Germany). The ocular spherical aberration (C4,0) and coma aberration (C3,1 and C3,-1) for a 4 mm diameter were obtained by an aberrometer (KR-1W, Topcon Corp., Japan). Multiple logistic regression analyses and the receiver operating characteristic (ROC) analyses were performed on these data to determine whether the two groups can be differentiated.
Results:
Multiple logistic regression analyses showed the BAD parameter D, the anterior corneal coma, and the total corneal coma were significant variables for differentiating FFK group from the normal group (P<0.001). The discriminant functions between FFK and normal cornea group reached an area under the ROC curve of 0.93. The sensitivity and the specificity were 82% and 92%, respectively.
Conclusions:
Most eyes of the FFK can be discriminated from the normal eyes by the indices generated from anterior and posterior surfaces and the thickness profile of the cornea.
Keywords: 479 cornea: clinical science •
574 keratoconus •
626 aberrations