KERATOCONUS FACTS

Keratoconus (KC) is a progressive, non-inflammatory disease of the cornea, The disease affects both eyes, but is frequently unequal between the eyes. Visual loss occurs primarily from irregular astigmatism and myopia. Secondarily, vision loss comes from corneal swelling and scarring.

All layers of the cornea are believed to be affected by KC, although the most notable features are the thinning of the central cornea with ruptures in the innermost layer. These ruptures allow fluid into the normally dry cornea causing wrinkles, distortion and eventual scarring.

In the US, reported prevalence in the general population varies from 50-200 cases per 100,000 people. It is usually an isolated ocular condition, but sometimes coexists with other ocular and systemic diseases such as Retinitis Pigmentosa, Mitral Valve Prolapse, atopic dermatitis, and Down Syndrome. Particular risk factors include history of ocular allergies, rigid contact lens (CL) wear and vigorous eye rubbing. Most KC cases appear spontaneously, although approximately 14% of them present with evidence of genetic transmission.

Incidence of KC seems to occur equally in males and females and typically presents at puberty and progresses until the third and fourth decades of life, although it can occur or progress at any age. KC progresses at various rates, but tends to progress more rapidly in young patients.

KC is divided into mild, moderate, and advanced. Mild KC starts with suspicious signs such as multiple, inadequate, spectacle corrections of one or both eyes which may include oblique astigmatism on refraction; irregular astigmatic keratometry values (egg-shaped) approximately 45 diopters [D]), are consistent with diagnosis.

Moderate KC often shows one or more classic corneal signs of KC such as more highly visible appearance of the corneal nerves; fine stress lines in the central cornea; approximately 50% of eyes with moderate KC develop the deposition of iron in the basal epithelial cells resulting in a ring shape brown haze in the lower aspect of the cornea; superficial corneal scarring and keratometry values increase to 45-52 D in typical cases.

Advanced KC often results in keratometry values greater than 52 D and enhancement of all corneal signs, symptoms, and visual loss/distortion as in less severe cases. Brown iron deposits are seen in about 70% of these patients and scarring in more than 60% of patients. Acute corneal swelling and loss of vision become more likely.

TREATMENT

Mild KC patients may see well with glasses for several years until the disease progresses. Specially fitted Keratoconic rigid, gas permeable contact lenses offer the most stable and comfortable vision for the majority of KC patients as the disease progresses.

Computerized corneal topography is used to confirm the diagnosis and facilitate the design of contact lenses for the best vision, comfort and shape retention of the cornea.

Lubricating eye drops and medication to reduce swelling may be necessary in more advanced KC cases with the most severe cases requiring corneal transplant surgery. Surgery replaces the diseased, misshapen cornea with a clear donor cornea which is sutured into place and allowed to heal. Vision after corneal transplant is generally good and the patient may even wear contact lenses again for any refinement of the vision.