Keratoconus is a non-inflammatory ectasia or protrusion of the cornea. Over a period of years (from a few years to 5 or more years) the cornea tends to thin and steepen. As the cornea thins and steepens, the patient will experience a decrease in vision which can be mild or severe. For mild to moderate degrees of keratoconus, eyeglasses or soft contact lenses may be able to provide the patient with clear comfortable vision. However, in the more advanced cases of keratoconus, eyeglasses or soft contact lenses will not be able to provide the patient with clear vision. In addition, conventional gas permeable contact lenses may be able to provide clear vision but these lenses tend to be unstable on an advanced keratoconic cornea.
In the great majority of the patients that we see with advanced keratoconus, the outer cellular layer of the cornea known as the epithelium is compromised or not intact. For this reason patients with advanced keratoconus will not be able to tolerate or support a soft, hybrid or conventional gas permeable lenses. With these lens designs the vision may be acceptable but the comfort will not be. Also, the small gas permeable lenses may tend to pop out of the eye or have excess movement causing discomfort and eye pain after a short wearing period.
The only lens that will provide clear stable vision, and excellent comfort to a patient with advanced keratoconus will be a gas permeable scleral lens, specifically a GVR Scleral lens. This is due to the fact that the GVR Scleral lens does not touch the compromised cornea. Instead, the GVR Scleral lens vaults over the cornea and is supported by the white portion of the eye known as the sclera. The space between the back of the lens and the front surface of the cornea is filled with unpreserved sterile saline solution. In other words, the front of the eye is always in a moist environment. Because of this, very often the GVR Scleral lens will act as a therapeutic device and help the compromised corneal tissue heal. In addition, the blinking action of the eyelids against the irritated cornea can cause further damage to the cornea. The GVR Scleral lens will protect the compromised cornea from the rubbing action of the eyelids against the irritated cornea.