Keratoconus is a progressive disease affecting the front window of the eye, the cornea, and results in poor vision that cannot be corrected fully with glasses. Keratoconus usually begins in the late teenage years. However, it can start in the 20s or early 30s. Keratoconus causes the “clear window” at the front of the eye to 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.
There is no known cause of keratoconus but it can be hereditary. It has also been linked to chronic eye rubbing as well as Down Syndrome.
Keratoconus does not result in blindness, although it can cause blurred and distorted vision. Improving a keratoconic's vision requires patience and persistence on the part of the patient and Doctor of Optometry since no single treatment option works on every patient and the condition can change frequently and rapidly.
Glasses may be used successfully to correct mild keratoconus. More moderate keratoconus is best corrected with rigid gas permeable contact lenses, which provide a smooth tear layer in front of the cornea, making clear vision possible. Because the lens is rigid, the tears between the lens and the cornea form a “liquid lens,” which smoothes the irregularities of the cornea and make clear vision possible again. Soft lenses, which form to the cornea and take up its curvature, are less successful at correcting keratoconus.
As keratoconus progresses, some thinning and scarring of the cornea can occur. Eventually, contact lenses may no longer be a successful treatment. Instead, a corneal transplant may be needed to surgically replace the cornea with one that has more regular and smooth surface. The prognosis for corneal transplant surgery is generally very good.
Content provided by the Canadian Association of Optometrists