Keratoconus Dallas Fort Worth
The word keratoconus is derived from two Greek words: kerato, meaning cornea, and konos, meaning cone. Keratoconus, therefore, is a condition in which the normally round shape of the cornea is distorted and a cone-like bulge develops, resulting in significant visual impairment. In simple terms, this means that the cornea, instead of being round like a basketball, is oblong like a football. This distortion usually begins in the late teens or early twenties and goes through a period of progression that can last five to 15 years or longer. As keratoconus progresses, the cornea protrudes forward, thins, and becomes irregular in shape. Often times, scars may form from extreme thinning of the cornea. Once the progression ceases, the patient's corneal shape is then stable for the remainder of his or her lifetime. The end result may range from mild ectasia (bulging) with minimal patient symptoms to severe disease with significantly decreased vision.
What causes Keratoconus?
Although we are very familiar with the way that keratoconus behaves clinically, we still are not able to fully explain why these corneal changes occur in a given individual. By and large, the causes of keratoconus are still unknown. There are however, several theories that may give us some insight. One scientific view is that keratoconus is developmental or genetic in origin. In some families, the hereditary pattern follows a strict Mendellian pattern, while in other families a hereditary pattern is absent or incomplete. It is generally thought that only 10% of families are at risk for more than one member being affected. Newer, more sensitive diagnostic methods, however, may prove that this percentage underestimates the true familial tendencies of keratoconus. Another theory is that keratoconus represents a degenerative condition. Many individuals with keratoconus are eye rubbers, which some believe can lead to corneal degeneration and resultant ectasia.
Who is susceptible to keratoconus?
It has been estimated to occur in 1/2,000 (USA data, AJO, 1986) persons in the general population but this number varies. As previously noted, this disease usually manifests at puberty or during adolescence. It is found in all parts of the United States and the rest of the world, with no known significant geographic, cultural or social pattern.
Signs and Symptoms
The first indication of keratoconus to the patient is a blurring and distortion of vision that, in its early stages, can be corrected with glasses. Due to disease progression, the spectacle prescription often requires frequent updates or changes. Occasionally, it is rapidly progressive. In the advanced stage, the patient may experience a sudden clouding of vision in one eye that clears over a period of weeks or months. This is called "acute hydrops" and is due to the sudden infusion of fluid into the stretched cornea. In advanced cases, superficial scars form at the apex of the corneal bulge and impair vision.
How is Keratoconus Treated?
In the mildest cases of keratoconus, ordinary eyeglasses may correct the near-sightedness and astigmatism caused by this warpage. However, specialty (i.e. scleral, hybrid, rigid gas permeable) contact lenses are the most effective way to correct vision adequately if keratoconus reaches moderate to advanced stages. Fitting patients with these custom contact lenses require great care, frequent checkups, and sequential adjustments to achieve good vision and comfort. It should be noted that technological advances in both specialty and soft lenses are made constantly, offering more and more possibilities for keratoconus patients.
The goal of contact lens wear in keratoconus patients is to maintain wear as long as the patients' visual acuity remains at an acceptable level, good ocular comfort is maintained and wearing time adequate for the individual is being realized. If these goals are not being met, then surgical options need to be considered (see our testimonial page to learn more).
Corneal Collagen Crosslinking (CXL) is an important treatment for patients with progressive keratoconus. as an alternative treatment for patients with mild to moderate, progressive keratoconus. This is a method for strengthening the corneal collagen and preventing further progression of the disease. A more detailed discussion of crosslinking is discussed later in this informational handout.
A corneal transplant may become necessary in approximately 15% of keratoconus patients. In this process much of the central cornea of the patient is removed and is replaced with the cornea of an organ donor. Eye banks across the country harvest healthy corneas from decedents and fulfill requests from eye surgeons for these corneas. Corneal transplantation for keratoconus is successful about 90% of the time. The major risks of the surgery include hemorrhage, infection, and organ rejection. While the surgical transplantation of a new cornea will resolve the basic problem of corneal surface irregularity, eyeglasses/contact lenses are usually needed for vision correction. In many cases, specialty contact lenses will be required to correct the large amount of corneal distortion that is sometimes associated with the transplant.