The cornea is a clear layer of tissue that covers the front of the eye. It is similar, structurally, to the crystal of a watch. Corneal clarity and surface regularity are extremely important in allowing light to be focused into the back of the eye and onto the retina ("film" of the eye).
The shape of the cornea, when viewed from the side, is rounded and smooth - similar to that of a crescent moon or basketball. Thinning and protrusion can give the cornea a cone-like appearance. When this structural change is present – the condition is called keratoconus.
Keratoconus is a progressive condition, often presenting when a patient is in their teens or early twenties, with decreased vision or visual distortion. This condition is typically not associated with redness, inflammation or other "acute" symptoms and therefore may go undetected for a long period of time. Over 95% of patients have involvement of both eyes, though it is not unusual for there to be asymmetric changes, with one eye being more involved than the other. In most cases the cornea is the only part of the eye that is abnormal. A family history of keratoconus is occasionally seen.
The cause of keratoconus is unknown. Certain allergic and arthritic disorders, Down's syndrome, chronic eye rubbing and contact lens wear have occasionally been associated.
The treatment approach to keratoconus follows an orderly progression from glasses to contact lenses to corneal transplantation. Glasses are an effective means of correcting mild keratoconus. As the cornea steepens and becomes more irregular glasses are no longer capable of providing adequate visual improvement. Contact lenses are the next approach in treatment. Hard or gas permeable contact lenses are preferred since these have the best chance of correcting surface irregularity and irregular astigmatism. Corneal transplant surgery is indicated when a patient cannot wear contact lenses for an acceptable period of time or when the vision, even with contacts, is unsatisfactory. Over ninety percent of corneal transplants for keratoconus are successful with the majority of patients obtaining vision of 20/40 or better afterwards with either glasses or contact lenses.
In April 2016, a new procedure, collagen crosslinking (specifically the Photrexa riboflavin solutions and the KXL System by Avedro, Inc.) was approved by the FDA for the treatment of progressive keratoconus. In the US, this is a first-in-class therapeutic treatment for this sight-threatening condition. Worldwide data going back more than 8 years has shown this to be an effective and safe option for stopping the progression of keratoconus. Michigan Cornea Consultants was among the leading recruiters nationally in a recent cornea crosslinking trial utilizing the KXL System by Avedro, Inc. so this is a procedure and a device with which we are already very familiar and quite experienced. For more information regarding crosslinking please visit the tab under surgery/forms.