Close up of eye demonstrating droopy eyelid


Keratoconus is a progressive eye disease that causes the cornea to thin and bulge into a cone-like shape. This cone shape causes distorted vision by deflecting the light as it enters the eye and hits the retina.

Early diagnosis and treatment of this condition are important to reduce the risk of disease progression and the requirement for corneal transplant surgery.


Symptoms of keratoconus

As the cornea weakens and thins, it bulges forward into a cone-like shape that affects your vision, especially in low-level light conditions such as night time. This is because the pupil is larger in low light, exposing more of the irregular cornea.

People with keratoconus usually have a high degree of myopia and astigmatism that can’t be corrected by ordinary glasses.

As the cornea becomes more and more conical and irregular, it causes progressive near-sightedness and an irregular astigmatism to develop. This creates additional problems, including blurred and distorted vision.

Common symptoms

  • Sudden change of vision in one eye
  • Blurred vision
  • Double vision
  • Distorted images
  • Multiple images
  • Streaking of lights
  • Haloes around bright lights.

During the development of keratoconus, bright light can begin to feel uncomfortable and things in bright light can become unclear.

This is due to light sensitivity brought on by the thinning of the cornea. As light hits the uneven cornea, the light scatters upon entry into the eye, causing light sensitivity.

Causes of keratoconus

The causes of keratoconus were not well understood until recently. New research has suggested that the corneal tissue that weakens as a result of the condition may be caused by an imbalance of enzymes in the cornea. As the tissues weaken due to the imbalance of enzymes, it undergoes oxidative damage from free radicals, which further weaken it and cause it to bulge forward.

Roughly 1 in 2000 people have keratoconus, and it affects men and women equally. However, it is more common in certain ethnic groups, for example it affects 1 in 450 South Asian people.

Keratoconus can sometimes run in the family. Between 10 and 14 percent of people with keratoconus have a history of it in their family, which means that the majority have no family history of keratoconus.

However, for the most part it is not understood why exactly people develop this condition.

Due to the shape of the cornea changing as a result of keratoconus, vision can change and become extremely poor. In later stages of keratoconus, scarring can cause a loss of transparency of the cornea and the eye may become unable to focus properly.

In keratoconus, collagen fibres in the cornea can slip over one another so that the lower half of the cornea bulges into a cone shape. This reduces vision, increases astigmatism and introduces aberrations that reduce vision quality.

The clear ‘bulge’ that characterises this condition develops very gradually, distorting the light rays that enter the eye and causing a distorted or ‘bumpy’ field of vision.

More Information About keratoconus

Keratoconus is often detected when assessing other eye conditions.

The main treatment available for keratoconus is to correct the vision problems that are caused by the irregular cornea. This often means using glasses or soft contact lenses to correct the problems. As the condition worsens though, vision will only be able to be corrected with hard contact lenses that are rigid gas permeable However, this only treats the symptoms of the disorder, and not the underlying cause.