|- !align=right | Contributing Editors: |. |-. Keratoconus is a common corneal disorder where the central or paracentral cornea undergoes progressive thinning and steepening causing irregular astigmatism.arly signs of Keratoconus include: • Asymmetric refracive error with high or progressive astigmatism. • Keratometry showing high astigmatism and irreguality (axis that do not add to 180 degrees). • Scissoring of the red reflex on ophthalmoscopy or retinoscopy.