Keratoconus is a non-inflammatory ectasia or protrusion of the cornea. It is characterized by progressive thinning and steepening of the central cornea. As the cornea steepens and thins, the patient experiences a decrease in vision which can be mild or severe depending on the amount of corneal tissue affected. The onset of keratoconus usually starts in the teenage years or early 20s. It rarely develops after the age of 35. Keratoconus shows no gender predilection and is bilateral in over 90% of cases. In general, the disease develops asymmetrically. Diagnosis of the disease in the second eye usually lags 6 or 7 years after diagnosis in the first. The incidence of keratoconus is about 2 to 3 people per 1000 population.
As the condition progresses, the distorted cornea will require a contact lens, usually rigid gas permeable. The progression of keratoconus is unpredictable. While keratoconus interferes with the clarity of a persons sight, it rarely causes blindness. With the latest contact lenses specifically designed for keratoconus, the need for a corneal transplant is extremely remote. Recently, several soft lens have been introduced for the treatment of keratoconus, including the Soft K lens and the Flex lens.
The characteristics of keratoconus have been known for at least 200 years, but the specific causes are still undetermined. Several theories have been proposed. One theory is that keratoconus is genetic in origin. About 7% of patients have other family members with the disease. Another view holds that keratoconus is secondary to some disease process. While there are many theories, research into keratoconus continues.
As Keratoconus advances, rigid gas permeable lenses are the first choice to correct vision adequately. Most of the time this is a permanent remedy. Because of the progression of the disease, it is important that the lenses are fitted with great care and are reassessed at least annually by eye care professionals. The lenses that we use have a complex geometry that takes into account the conical shape of the cornea for all stages of the condition. The lenses have multiple curves which are custom designed to fit each individual cone correctly without traumatizing the delicate compromised corneal tissue. For almost all patients, this means better comfort and optimum visual acuity. Additional features of these newest of keratoconus lens designs include:
1. The complex geometry of the lens can be customized to suit each eye and correct all of the myopia and
astigmatism associated with the keratoconus.
2. They are easy to insert, remove and clean.
3. They provide excellent health to the eye, because they allow the cornea to “breath” oxygen directly through the lens.
4. The central zone of the lens fits directly over the cone. Consequently, the lens will not slide around on the cornea causing ocular irritation or scarring. The concept of this unique fit is similar to the manner in which a bra is fitted over a breast.
In the more advanced cases of Keratoconus, Pellucid Marginal Degeneration and Post-Lasik Ectasia, small diameter gas permeable lenses will not work. This is especially true when there is a degradation of the outer cellular layer of the Cornea known as the Epithelium. When this layer of the Cornea is compromised, the Cornea will not be able to support any form of lens whether it be a soft lens, a hybrid lens or a gas permeable contact lens. The only lens that will provide clear, comfortable and stable vision is a gas permeable Scleral Lens. This lens will work because it does not touch the Cornea. In fact, the entire lens vaults over the compromised Cornea and is supported by the white portion of the eye known as the Sclera. The space between the back surface of the lens and the front surface of the Cornea is filled with unpreserved Sterile Saline Solution. Therefore, the front surface of the eye is always in a liquid environment. Vision and comfort is almost always excellent.
These Scleral Lenses are not only used by me for the treatment of Advanced Keratoconus, but also for the restoration of vision and comfort in those patients who have suffered loss of vision due to Corneal Transplant Surgery, Post-Refractive Surgeries such as Lasik, R-K, PRK, and Chronic Dry Eye due to Disease and Ocular Trauma. In addition, the Scleral Lenses have a Therapeutic effect on the Cornea. Many Compromised Corneas become significantly healthier after having a Scleral Lens protecting the delicate tissue from the environment and from the lids rubbing against this tissue.
The lenses that you are wearing are probably not fit correctly. We see this often when the lenses are fit too flat, and the design of the lens is not appropriate. The lenses are moving excessively over the cornea with each blink causing abrasions to the apex of the cone. If this continues, irreversible scarring will result and visual acuity will diminish. When I get to see a cornea like this, I often have to refit with a new rigid lens over a special soft lens which acts as a bandage. The soft lens allows the cornea to heal, while the rigid lens provides vision. Typically, this “piggy back” combination lasts no more than a few weeks. As the cornea heals, new measurements of the corneal curves are taken. It is not unusual to encounter changes in the curves and contour of the healed cornea. As this takes place, new rigid lenses are ordered to fit the healed cornea.