Abstract
Purpose: :
To investigate the application of anterior corneal and ocular aberrations in detecting mildly ectatic corneas.
Methods: :
We retrospectively reviewed the data of 220 eyes separated into 3 groups by the Nidek Corneal Navigator System automated corneal classification software: normal (N) (n=123), Forme Fruste Keratoconus (N Topography with contralateral KC) (FFKC) (n=34) and KC (n=63). Anterior corneal and ocular aberrations were obtained with the OPD Scan and compared using a Kruskall Wallis test. Evaluation of these data to discriminate between the three groups was assessed using a Receiver-Operating Characteristic (ROC) curve analysis.
Results: :
Corneal and Ocular tilt, vertical coma and trefoil were significantly different in the FFKC as compared to the N group however their clinical relevance was small. The association of individual Zernike coefficients in a discriminant function differentiates between FFKC and normal corneas with a sensitivity of 91% and a specificity of 94%. The discriminant functions between the FFKC and the N group and between the KC and the N group reached an Area under the ROC curve of 0.98 and 0.96 respectively.
Conclusions: :
Indices generated from corneal and ocular wavefront can identify very mild forms of ectasia that may be undetected by a Placido-based neural network programs.
Keywords: refractive surgery: corneal topography • refractive surgery • refractive surgery: LASIK