The relationship between the cornea and the optic disc

Objective To evaluate the structural relationship between the cornea and the optic disc in normal subjects. Methods This hospital-based observational study included 205 eyes from 205 individuals who were diagnosed as normal at our glaucoma clinic. The subjects underwent an eye examination, optic disc imaging with optic disc photography, optical coherence tomography, IOL master, specular microscopy, and ultrasound corneal pachymetry. Results In univariate regression models (Pearson's correlation coefficient), the cup-to-disc (CD) ratio showed a negative correlation with corneal curvature (r=-0.315, Po0.001) and central corneal thickness (r=-0.206, P=0.005), and a positive correlation with white-to-white diameter (horizontal limbus to limbus distance, r=0.215, P=0.003). In multiple linear regression models with CD ratio as the dependant parameter, the CD ratio was still significantly associated with corneal curvature (β=-0.205, P=0.011) and white-to-white diameter (β=0.207, P=0.010). The central corneal thickness failed to show statistical significance, but did show a negative correlation with borderline significance (β=-0.133, P=0.075). Conclusions Eyes with a large CD ratio have large and flat corneas; this may suggest that there is a structural relationship between the cornea and the optic disc. These results can be helpful in analysing the anatomical relationship between the cornea and the optic disc.