Investigation of the Efficacy of the Cone Location and Magnitude Index in the Diagnosis of Keratoconus.
OBJECTIVE
The aim of this study was to investigate the sensitivity, specificity, and accuracy of The Cone Location and Magnitude Index (CLMI) in keratoconus diagnosis.


METHODS
301 eyes of 159 keratoconus patients and 394 eyes of 265 refractive surgery candidates as a control group were enrolled in this retrospective clinical study. CLMI was compared with keratometric corneal topography parameters, wavefront aberrations, and pachymetry data derived from optical coherence tomography using independent sample t-tests and ROC curves. Logistic regression analysis was applied to determine the most accurate parameter in keratoconus diagnosis. Pearson's correlation analysis was used to determine the correlation between CLMI and the other measurements.


RESULTS
Average axial CLMI (aCLMI) was 8.19 ± 6.15 D in the keratoconus group and 0.83 ± 0.62 D in the control group (p = 0.001). aCLMI had the greatest sensitivity (89%), specificity (94%), and accuracy (92%) for the keratoconus diagnosis at the best cut-off point of 1.82 according to the ROC curve. Logistic regression analysis selected aCLMI as the most accurate measurement among the other parameters (accuracy 92.8%). aCLMI showed strongest correlations with coma-like aberrations (r = 0.881), total high-order aberrations (r = 0.858), and vertical coma (r = -0.814), respectively.


CONCLUSIONS
CLMI is a robust index for screening keratoconus with high sensitivity, specificity, and accuracy.
a Ophthalmology Department , Ardahan State Hospital , Ardahan , Turkey .
Sücattin İlker
Sİ
Kocamış
b Ophthalmology Department , Yıldırım Beyazıt University School of Medicine , Ankara , Turkey , and.
Hasan Basri
HB
Çakmak
b Ophthalmology Department , Yıldırım Beyazıt University School of Medicine , Ankara , Turkey , and.
Nurullah
N
Çağıl
c Ankara Atatürk Training and Research Hospital Ophthalmology Department , Ankara , Turkey.
Yasin
Y
Toklu
D000328:Adult; D003315:Cornea / Q000473:pathology*; D063171:Corneal Pachymetry; D019781:Corneal Topography; D057108:Corneal Wavefront Aberration / Q000175:diagnosis; D004108:Dilatation, Pathologic / Q000175:diagnosis; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis*; D008297:Male; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D041623:Tomography, Optical Coherence; D055815:Young Adult
CLMI; corneal topography; keratoconus; keratometry; wavefront