Keratoconus Support Group

Keratoconus (from Greek: kerato- horn, cornea; and Latin: conus cone), is a degenerative non-inflammatory disorder of the eye in which structural changes within the cornea cause it to thin and change to a more conical shape than its normal even curve. Keratoconus can cause substantial distortion of the vision, with multiple images, streaking and sensitivity to light all often reported by the patient. Though frequently thought of as a rare condition, keratoconus is the most common distrophy of the cornea, affecting around one person in a thousand, and seems to occur equally in all ethnic groups worldwide. It is typically diagnosed in the patient's adolescent years and attains its most severe state in the twenties and thirties.

Keratoconus is a little-understood disease with an uncertain cause, and the course of its progression following diagnosis is unpredictable. The associated deterioration in vision, if in both eyes, can affect the person's ability, for example, to drive a car legally. It does not, however, lead to blindness, and in most cases, corrective lenses are effective enough to allow the patient to continue to drive and likewise function normally. Further progression of the disease may lead to a need for surgery. Keratoconus continues to be somewhat of a mystery disease, but it can be successfully managed with a variety of clinical and surgical techniques often with little or no impairment to the patient's quality of life.

In early stages of keratoconus, spectacles can suffice to correct for the mild astigmatism. As the condition progresses, spectacles may fail to provide the patient with a satisfactory degree of visual acuity, and most clinical practitioners will move to managing the condition with contact lenses.

Between 10% to 25% of cases of keratoconus will progress to a point where vision correction is no longer possible, thinning of the cornea becomes excessive, or scarring as a result of contact lens wear causes problems of its own, and a corneal transplantation or penetrating keratoplasty becomes required. Keratoconus is the most common grounds for conducting a penetrating keratoplasty, accounting for around a quarter of such procedures.[36] The corneal transplant surgeon trephines a lenticule of corneal tissue and then grafts the donor cornea to the existing eye tissue, usually using a combination of running and individual sutures. The cornea does not have a direct blood supply, and so donor tissue is not required to be blood type matched. Eye banks check the donor corneas for any disease or cellular irregularities.

A recent surgical alternative to corneal transplant is the insertion of intrastromal corneal ring segments. A small incision is made in the periphery of the cornea and two thin arcs of polymethyl methacrylate slid between the layers of the corneal stroma either side of the pupil, the incision then being closed. The segments push out against the curvature of the cornea, flattening the peak of the cone and returning it to a more natural shape. The procedure, carried out on an outpatient basis under local anaesthesia, offers the benefit of being reversible and even potentially exchangeable as it involves no removal of eye tissue.

A new treatment which has shown success but which has not yet been approved in all countries involves a one-time application of riboflavin eye drops to the eye. The riboflavin, when activated by approximately 30 minutes illumination with UV-A light, augments the collagen cross-links within the stroma and so recovers some of the cornea's mechanical strength. The treatment, developed at the Dresden University of Technology, has been shown to slow or arrest the progression of keratoconus, and in some cases even reverse it, particularly when applied in combination with intracorneal ring segments.