The cone can assume various shapes and sizes, and the apex can be at various locations in relation to the central cornea. Locating this ring initially may be made easier by using a cobalt filter and carefully focusing on the superior half of the cornea's epithelium. Once located, the ring should be viewed in white light to assess its extent. Lines of Vogt Lines of Vogt are small and brushlike lines, generally vertical but they can be oblique. Lines of Vogt are more easily viewed when they reappear after this pressure is removed.
Rigid lens wear sometimes accentuates the lines.
In advanced cases of keratoconus, posterior corneal folds may also be present. Additionally, as the disease progresses, the cone is often displaced inferiorly. Apical thinning described is believed to represent an actual reduction in the number of stromal lamellae rather than an overall thinning process. Deep opacity of the cornea are not uncommon in keratoconus. It has also been reported that flat-fitting contact lenses may produce or accelerate corneal scarring.