A new approach to keratoconus detection based on corneal morphogeometric analysis

PURPOSE: To characterize corneal structural changes in keratoconus using a new morphogeometric approach and to evaluate its potential diagnostic ability. METHODS: Comparative study including 464 eyes of 464 patients (age, 16 and 72 years) divided into two groups: control group (143 healthy eyes) and keratoconus group (321 keratoconus eyes). Topographic information (Sirius, CSO, Italy) was processed with SolidWorks v2012 and a solid model representing the geometry of each cornea was generated. The following parameters were defined: anterior (A(ant)) and posterior (A(post)) corneal surface areas, area of the cornea within the sagittal plane passing through the Z axis and the apex (A(apexant), A(apexpost)) and minimum thickness points (A(mctant), A(mctpost)) of the anterior and posterior corneal surfaces, and average distance from the Z axis to the apex (D(apexant), D(apexpost)) and minimum thickness points (D(mctant), D(mctpost)) of both corneal surfaces. RESULTS: Significant differences among control and keratoconus group were found in A(apexant), A(apexpost), A(mctant), A(mctpost), D(apexant), D(apexpost) (all p<0.001), A(post) (p = 0.014), and D(mctpost) (p = 0.035). Significant correlations in keratoconus group were found between A(ant) and A(post) (r = 0.836), A(mctant) and A(mctpost) (r = 0.983), and D(mctant) and D(mctpost) (r = 0.954, all p<0.001). A logistic regression analysis revealed that the detection of keratoconus grade I (Amsler Krumeich) was related to A(post), A(tot), A(apexant), A(mctant), A(mctpost), D(apexpost), D(mctant) and D(mctpost) (Hosmer-Lemeshow: p>0.05, R(2) Nagelkerke: 0.926). The overall percentage of cases correctly classified by the model was 97.30%. CONCLUSIONS: Our morphogeometric approach based on the analysis of the cornea as a solid is useful for the characterization and detection of keratoconus.