Keratoconus

What is Keratoconus?

Keratoconus is a progressive eye disease in which the normally round cornea (front window of the eyeball) thins and bulges into a cone-like shape. This cone shape makes the corneal surface irregular and causes distorted vision. It is a fairly common eye condition in New Zealand, especially among Maori, Pacific Island and Indian ethnic populations.

What causes Keratoconus?

Keratoconus tends to run in families and up to 50% of keratoconus is said to have a genetic cause.  Allergic eye conditions and eye rubbing are linked to the development of keratoconus.

What are the symptoms & signs of Keratoconus?

Children with keratoconus often present with gradual onset of blurred vision, image ghosting and light sensitivity. The sudden onset of a painful cloudy cornea (corneal hydrops) can occur due to the breakdown of the corneal tissue in moderate and advanced cases of keratoconus.

What are the ocular, systemic associations of Keratoconus?

Keratoconus is associated with hayfever, atopic diseases, asthma and eye rubbing.  There is higher prevalence of keratoconus in people with Down Syndrome (Trisomy 21).

How is Keratoconus diagnosed?

Diagnosis of keratoconus can be made by slit-lamp examination and observation of central or inferior corneal thinning. Computerized videokeratography is also useful in detecting early keratoconus and allows doctors to follow its progression.

What are the treatments of Keratoconus?

In the early stages, corrective glasses are effective to provide clear focused vision and prevent the potential development of amblyopia (lazy eye).  Contact lenses (especially rigid gas permeable (RGP) contact lenses) are required by many with keratoconus as they provide the best corrected acuity.  Corneal transplant is effective in advanced cases of keratoconus with corneal scarring.

Cross linking is the new emerging treatment for those with early to moderate keratoconus. This treatment strengthens the collagen tissue in the cornea and slows down keratoconus progression.

Educational Implications

Behaviours or conditions that might indicate keratoconus

• Progressively poor vision not easily corrected with eye glasses.
• In the early stages a young person may describe their vision as mild blurring, straight lines may look bent or wavy, they may show increased sensitivity to light and glare or they may have eye redness or swelling.
• In later stages the vision may become more blurry and distorted, increased near-sightedness or astigmatism may occur and contact lenses may no longer fit and feel uncomfortable.
• Conditions such as allergy (hay fever), eczema and asthma are common in young people with Keratoconus.
• Eye rubbing.

What to do

• The young person should visit an optometrist or ophthalmologist to determine diagnosis and treatment.
• Parents, whānau and caregivers will need to review treatment options. Most children with Keratoconus require glasses, contact lenses and/or surgery;
• Ensure the young person does not rub or push on their eyes. This can damage thin corneal tissue and make symptoms worse.
• Encourage the young person to wear their spectacles or contacts. This will help them see more clearly and may reduce glare and photophobia.
• Recognising facial expressions can often be difficult. It is worth trying to find out at what distance facial expressions can be seen and responded to then work within this distance.
• Reduce glare by positioning the young person so their back is to any glare from windows or lights and also avoid shadows on their work.