• Symptoms

    The earliest symptom is subtle blurring of vision that cannot be corrected with glasses. (Vision can generally be corrected to 20/20 with rigid, gas-permeable contact lenses.)

    Most people who develop keratoconus start out nearsighted. The nearsightedness tends to become worse over time.

    Signs and tests

    Keratoconus is often discovered during adolescence. It can usually be diagnosed with slit-lamp examination of the cornea. The most accurate test is called corneal topography, which creates a map of the curve of the cornea.

    When keratoconus is advanced, the cornea will be thinner at the point of the cone. This can be measured with a painless test called pachymetry.