Poor vision that cannot be corrected fully with glasses may indicate a condition known as conical cornea or keratoconus. A rare condition, keratoconus primarily affects people in their early 20’s.
With keratoconus, the cornea, the “clear window” at the front of the eye, may become thin and bow outwards. It is this irregular distortion of the cornea that makes vision correction with glasses less than optimal. For this reason other means of correcting vision are often necessary.