Diseases of the cornea prevent or distort the light passing through. A corneal transplant is used to replace the damaged cornea with a clear healthy one from a deceased donor.

Keratoconus

In keratoconus, the cornea of the eye develops a conical shape that impairs vision. In most cases, it appears before the age of 30.

Keratoconus

What is keratoconus?

Keratoconus is a common eye condition that affects the cornea - the front window of the eye. The cornea helps to bend and focus light to help us see.

In keratoconus, the cornea gets thinner over time. As a result, the round shape of the cornea gets distorted and a cone-like shape develops.

When the cornea loses its shape, light can't come to a sharp focus on the retina. This can cause blurry vision, double vision, astigmatism, short sightedness or light sensitivity. If left untreated, vision will continue to get worse.

In most cases, keratoconus appears between the ages of 16 and 30 years and stabilises by middle age. Due to its early onset, it can impact school, work, social and family life if it's not treated.

How common is it?

Estimates vary but approximately 1 in 2000 New Zealander's are affected by keratoconus, with 60% being male. It's currently the second-most reason for corneal transplant in New Zealand. Maori and Pacific Island communities appear to have a slightly higher than average prevalence.

Causes and risk factors

The exact cause of keratoconus is not known. But both genetic and environmental factors seem to play a role.

Many people who are affected have no family history of the condition. But it is likely to have a genetic component.

Keratoconus often occurs alongside diseases where people have itchy eyes. For example, hay fever, allergies and asthma. Lots of vigorous eye rubbing can break down the fibres of the cornea. This might increase risk of keratoconus, but the exact link is still unclear.

Signs and symptoms

In the early stages, keratoconus may not cause any symptoms.

As the condition progresses, it causes blurring and distorted vision. One of the tell-tale signs of the disease is frequent changes in glasses prescription.

Other possible symptoms include:

  • increased light sensitivity
  • halos around light sources
  • double images (especially at night)

Diagnosis

Keratoconus can be hard to diagnose early on as the symptoms are like other eye conditions. Early diagnosis requires a special camera to map the shape of the cornea. This is not part of a routine eye exam.

If your eye healthcare provider picks up signs of the disease, they will refer you to someone who specialises in keratoconus.

Treatment

There is no known cure for keratoconus or way of reversing damage done to the cornea. But treatment can help manage most vision loss caused by the condition.

Corneal collagen crosslinking is a new treatment option to slow the progress of the disease. It involves applying vitamin B2 drops and UVA light to stiffen the cornea and stop it losing its shape.

In the early stages of keratoconus, glasses or soft contact lenses can correct vision. As the condition progresses, treatment moves to hard contact lenses.

In advanced cases, corneal transplant surgery is required to improve vision. Even after surgery, glasses or contact lenses may still be needed.

Can it be prevented?

Keratoconus cannot be prevented. But treatment can manage symptoms and slow disease progression.

Fuchs' endothelial dystrophy

In Fuchs' endothelial dystrophy, the cornea of the eye becomes cloudy over time. This causes blurred or hazy vision that progressively worsens.

Fuchs endothelial dystrophy

Overview

Fuchs' endothelial dystrophy is a disease of the cornea - the clear window at the front of the eye. The cornea allows light to enter the eye and is the main part of the eye used for focusing.

The cells lining the cornea (endothelial cells) help maintain fluid balance and prevent the cornea from swelling. In Fuchs' endothelial dystrophy, the endothelial cells gradually die, and fluid builds up within the cornea. This makes it difficult to focus, causing blurred vision. The condition usually affects both eyes. It can worsen with age and cataract surgery.

How common is it?

Fuchs' endothelial dystrophy affects one in every 25 New Zealander's over the age of 40. This is almost 200,000 people.

Causes and risk factors

It is unknown what causes the endothelial cells of the cornea to die. However, there are three main risk factors for developing the disease:

  • Family history - the condition is often inherited
  • Age - the disease typically starts when people are in adulthood. But most people don't develop symptoms until they reach their 50's
  • Sex - Fuchs' endothelial dystrophy is more common in women than in men

Signs and symptoms

Fuchs' endothelial dystrophy tends to progress slowly over many years.

In the early stage of the condition, you may notice few (if any) symptoms. Vision may be hazy in the morning but improve as the day goes on.

As the condition progresses, vision will typically remain blurry all day. Other symptoms may include:

  • pain
  • sandy or gritty feeling in your eyes
  • being extra sensitive to bright light

If you have these symptoms, especially if they get worse over time, see your eye healthcare provider.

Diagnosis

An ophthalmologist or optometrist can detect the disease with an eye exam.

They will measure the thickness of your cornea and check for tiny blisters at the front and bumps at the back. They may also count your endothelial cells using a special photo of your cornea.

Treatment

There is no medical treatment for Fuchs' endothelial dystrophy. But it is possible to control the symptoms and minimise vision loss.

Eye drop medications or ointments can reduce swelling in the cornea. Self-care strategies, such as drying the surface of the cornea with a hairdryer, can also help.

If the disease is advanced and there's vision loss, you may need a corneal transplant. This operation replaces the impaired corneal cells with all or part of a healthy clear cornea from a donor.

Your eye healthcare provider will discuss what treatments are best for your condition.

Can it be prevented?

Fuchs' endothelial dystrophy cannot be prevented. But having regular eye exams after the age of 50 can catch the disease before it starts causing pain and vision loss.