Indiana Keratoconus Treatment

Keratoconus (KCN) is a disease characterized by thinning and protrusion of the cornea, resulting in an irregular, conical shape. Irregular astigmatism occurs as the condition progresses, and results in blurred vision which can be impossible to correct with spectacles. Usually the disease occurs in both eyes, and involves the central cornea with the apex of the cone just below the visual axis.

Prevalence is roughly 100 to 200 per 100,000 people, and occurs in all races. 85% of cases are bilateral. Sensitive techniques such as corneal topography often detect KCN in the fellow eye in cases thought to be unilateral based on physical examination and refraction. Onset of disease is often in puberty. Progression occurs slowly over decades, and often stabilizes. In progressive cases, severe irregular astigmatism and scarring may require corneal transplantation to restore useful vision to the eye.

Heredity of the disease has not been clearly established. While there are families in which multiple persons are affected, confounding factors such as atopic disease and contact lens use make analysis difficult. As a general rule, chances of a blood relative developing clinical keratoconus are less than 10%.

Associated conditions include atopic disease (atopic or allergic dermatitis, allergic rhinitis, asthma), Down's syndrome (5-8 % of Down's patients), and connective tissue disorders (Ehlers-Danlos syndrome and osteogenesis imperfecta). Chronic eye rubbing is associated with KCN and may accelerate progression of the disease.

Findings in keratoconus include protrusion of the cornea, striae or wrinkles of the posterior cornea (Vogt's striae), superficial scarring of the anterior cornea, and staining of the corneal surface epithelium with iron (Fleischer ring). Corneal hydrops, or marked swelling of the cornea may occur when severe bulging of the cornea results in a tear in the deepest layer of the cornea (Descemet's membrane), allowing fluid from the inside of the eye to permeate the cornea. Severe haziness, often accompanied by blister like lesions of the superficial cornea, result in impairment of vision and discomfort.

Treatment of keratoconus can be divided into three tiers. For patients who can be corrected with spectacles, no other treatment is necessary, although behavior such as eye rubbing should be modified. Control of systemic allergic disease with antihistamines may help achieve this goal by decreasing itching of the eye and eyelids.

When irregular astigmatism makes clear vision with spectacles impossible, rigid gas permeable (RGP) contact lenses are the next stage of therapy. The rigid lens masks the underlying irregular cornea and functions as the new refractive surface of the eye, with the tear film filling in the space between the back of the contact lens and the front of the eye. However, the irregular shape of the cornea makes fitting these lenses difficult, and the experience and expertise of the contact lens fitter is very important in determining the success of this intervention. New surgical techniques such as deep anterior lamellar keratoplasty and intrastromal ring segments (Intacs TM) are also surgical options.

If the condition progresses to the point where contact lenses cannot be fit, cornea transplantation may be considered to restore a more normal shape to the cornea. Data from the Cornea Research Foundation of America database of corneal transplants shows that transplants performed for keratoconus are in the highest category for successful outcome. The database is currently being used by surgeons at the Price Vision Group to assess methods for reducing post-operative nearsightedness in patients undergoing corneal transplantation for KCN.