This is an abnormal curvature of the cornea (the clear window that makes up the front of the eye).  Normally, the cornea is spherical with a surface shape like a basketball.  People with astigmatism have a cornea that is shaped like an American football. These shapes are easy to “fix” with glasses. Keratoconus is a whole different game.  With this condition, the cornea weakens over time and takes on an irregular shape … like that of a “beer belly” or a “pointy cone.”  This irregular surface creates optical aberrations that are impossible to correct using glasses.  Hard contacts can be helpful, as they create a rounder ‘surface’ on the eye, but are difficult to fit. If bad enough, keratoconus eyes may require a corneal transplant to regain useful vision. The cause of keratoconus is believed to be from a defect in the collagen tissue that makes up the eye. Diagnosis is usually made with microscopic examination of the eye and by corneal topography (a machine that maps out the surface shape of the eye like a topographical map).  People with keratoconus are poor candidates for LASIK as the laser procedure makes the cornea thinner and further weakens it.

Dr. Timothy Root is a practicing ophthalmologist and cataract surgeon in Daytona Beach, Florida. His books, video lectures, and training resources can be found at:


  1. It was super interesting to learn that the cornea shape of one with keratoconus is more like a cone or bear belly.” Is this a common issue? I don’t think I’ve ever met anyone with this condition. It’s good to know that hard contacts can be helpful to fix it or a transplant if they really need it. Thanks for sharing this, it was really interesting to read!


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