This is a condition where the centre of the cornea thins. The pressure of the aqueous humour behind the cornea causes it to become slightly conical in shape, and to bow forward much more than normal. This results in irregular astigmatism, which initially can be corrected with spectacles.As it progresses, visual acuity is inadequate with spectacles, and contact lenses are required. This restores stable visual acuity by replacing the irregular corneal surface with a smooth refractive surface. Depending on the progression of the condition specialist contact lenses might be required.In some cases referral to an ophthalmologist may be required as other treatment options may need to be considered.