Keratoconus is an eye condition that is non-inflammatory. A progressive thinning of the normally dome-shaped cornea characterises the condition and a cone-shaped bulge develops as a result.
This then leads to significant impairment in a person’s vision. Keratoconus can affect 1 out of 2,000 people. The disease cuts across gender and race. While the cause has yet to be precisely identified, genetics, allergies and environmental conditions may factor.
Patients with keratoconus usually develop the disease between the ages of 8 and 45. The disease will usually manifest itself during the teenage years and worsen further in the 20s. It then becomes more stable when a person reaches about 30 years old. Both eyes are usually affected, though the timing and the progression of the disease may differ between the two eyes. Typically one eye is affected more than the other.
Symptoms of Keratoconus
A person suffering from the disease will first suffer slight changes in vision. As the condition progresses however, the person’s vision may start to go up and down, resulting in constant changes in the prescription grades of their eyeglasses and contact lens. The disease will then worsen as the outer portion of the eye starts to change to a cone-shaped bulge. The light rays entering the eye thus become really distorted, resulting in irregular astigmatism.
One of the questions that Jim Kokkinakis (optometrist at The Eye Practice) is often asked is “will I go blind?” While the danger of becoming completely blind is low, severe cases of keratoconus may impair one’s vision so significantly that simple daily activities will be difficult to do.
Keratoconus Treatment Options
Early Stage – Eyeglasses and Contact Lenses
The earliest stage of the disease is often successfully addressed with a properly prescribed pair of glasses or soft contact lenses to correct the vision problems of the patient. Once the disease progresses past the mild stage, to brace against the cone-shaped bulge in the cornea, rigid gas permeable contact lens may be prescribed.
Surgical Option – Corneal Transplant Surgery
If a patient’s vision can no longer function through the use of contact lenses, or if all attempts at achieving a successful contact lens fit have failed, then a surgical option may be recommended. Around a fifth of all patients with keratoconus go through a corneal transplant. More than 4,000 corneal transplant surgeries per year are performed in the United States alone. In Australia it is around 1,500 procedures per year. This procedure has an extremely high success rate. Keratoconus is a leading reason for corneal transplantation.
The surgery has its drawbacks however. A corneal graft typically lasts only for around 15 years, meaning a patient may have to go through several procedures in his or her lifetime, with shorter graft-life each time. The procedure is also quite invasive, as it involves the removal of a portion of the cornea for replacement with the donor tissue. The patient also faces a long recovery period, often with unstable vision.
Collagen Cross Linking
One of the most significant advances in keratoconus treatment over the past five years has been the use of collagen cross-linking to stop the progression of keratoconus. This is a surgical procedure, but unlike corneal graft, it does not penetrate the cornea. Instead, ultra-violet light is applied to the cornea in the presence of riboflavin (a B vitamin). This causes the collagen fibres of the cornea to link together, forming a firmer cornea and preventing progression of the disease. We wrote more about collagen cross linking here.
The Intacs Alternative
Intacs are a type of medical device known generically as intra-corneal ring segments. They are placed surgically within the cornea itself and do not penetrate the eye. They support the bulging dome caused by the disease and can be effective in reducing irregular astigmatism and improving vision.
The Intacs procedure is an alternative to corneal graft surgery for some keratoconus patients. It is less invasive as it does not require the removal of corneal tissue. Instead, it works by reshaping the patient’s cornea back to its natural dome shape. This is done through specially designed medical plastic corneal inserts that are placed under the surface of the cornea.
Improvement in vision is often immediate. The patient will also undergo a short recovery period.
Limitations with Intacs include:
• Cannot be performed on moderate or high cases of keratoconus. Best reserved for mild cases.
• Contact lenses typically are more difficult to fit after Intacs. It is imperative that an expert contact lens fitter has ruled out successful contact lens wear (usually due to excessive sensitivity) before proceeding with Intacs.
At The Eye Practice, managing keratoconus is our area of expertise. If you are suitable for Intacs, or a similar procedure called KeraRings, we can refer you to a surgeon near you but more importantly one that performs this specialised procedure expertly.
Call The Eye Practice optometrists (Sydney CBD) on (02) 9290 1899 to book an appointment with Dr Jim Kokkinakis.
This article was originally published on our website on 26th November 2012 but has been updated for accuracy and relevance.