Keratoconus

Auckland Eye Keratoconus page

Keratoconus is an inherited condition of the cornea.

The first indication of keratoconus is often reduced vision even when wearing glasses or contact lenses

Keratoconus is an inherited condition where the cornea becomes thinned, distorted and irregular leading to a reduction in vision. Initially symptoms can be slight blurring or distortion of vision with increased sensitivity to glare and light and as it progresses vision may become more distorted.

Keratoconus is an inherited condition of the cornea. The cornea is the transparent front surface of the eye. In keratoconus, the normally round cornea becomes thinned, distorted and irregular (cone shaped). This abnormal shape prevents the light entering the eye from being focused correctly on the retina and causes distortion of vision. Because of the cornea's irregular shape, patients with keratoconus are usually very nearsighted and have a high degree of astigmatism that is not correctable with glasses.

Keratoconus treatment depends on its severity. Initially, glasses or soft contact lenses can improve vision however, as the cornea continues to thin and change shape, hard contact lenses are a better option. When vision can no longer be improved with contact lenses, surgery may be indicated. Corneal collagen cross linking is currently the main surgical management. Our corneal specialists will advise the best treatment solution for you.

Auckland Eye is an affiliated provider to Southern Cross Health Society for collagen cross-linking.

For more information on keratoconus and treatment, please contact our friendly specialist team.

  • Nearsightedness
  • Astigmatism
  • Blurred vision - even when wearing glasses or contact lenses
  • Glare at night
  • Eye rubbing
  • Light sensitivity
  • Frequent prescription changes in glasses and contact lenses

Studies have provided evidence to suggest a genetic basis for keratoconus. Up to 50% of family members of patients with keratoconus have subtle signs of early keratoconus. Keratoconus can occur in association with a variety of diseases, including eczema, hay fever and asthma. Keratoconus is more common in people with Down's syndrome.

Normal eye

Normal eye

Eye with Keratoconus

Eye with Keratoconus

In its earliest stages, keratoconus causes slight blurring and distortion of vision and increased sensitivity to glare and light. These symptoms usually appear in the late teens or early twenties. Keratoconus may progress for 10-20 years and then slow in its progression. Each eye may be affected differently and one eye may have very poor vision while the other eye retains perfect vision.

As keratoconus progresses, the cornea bulges more and the vision may become more distorted. The cornea is weaker than the normal cornea and may be damaged by minor trauma. For this reason people with keratoconus should not participate in contact sports.

In a small number of cases, hydrops occurs where the cornea will swell and cause a sudden and significant decrease in vision. This occurs when the stretching causes a tiny split to develop in the inside surface of the cornea. The swelling may last for weeks or months as the crack heals and is gradually replaced by scar tissue. If this sudden swelling does occur, your doctor can prescribe eyedrops for temporary relief, but there are no medicines that can prevent the disorder from progressing.

Often the scarring causes the vision to be somewhat worse after an attack of hydrops. Sometimes however the scarring may improve the shape of the cornea, improving the vision. The cornea may become very thin but it is very unlikely to spontaneously rupture.

Treatment of keratoconus depends on the severity of the condition. Initially, eyeglasses or soft contact lenses are successful in correcting the myopia (near sightedness) and astigmatism. 

As the disorder progresses and the cornea continues to thin and change shape, rigid gas permeable contact lenses can be prescribed to correct vision. In most cases, this is adequate but the contact lenses must be carefully fitted by an optometrist and frequent checkups and lens changes may be needed to achieve and maintain good vision.

A government subsidy may be available to help with the costs of contact lens wear. Contact lens wear in keratoconus does not alter the progression
of the disease or cure the condition. It merely gives improved vision while the lenses are being worn. When good vision can no longer be attained with contact lenses because of corneal scarring or intolerance to contact lens wear, surgery may be indicated.

Corneal graft surgery

Some patients maybe suitable for corneal implants, which work by flattening the steep part of the cornea to reduce vision distortion caused by keratoconus. The end result depends on the degree of keratoconus being treated.

For severe keratoconus, corneal transplantation (or graft surgery) may be the only option. This procedure is usually performed under general anaesthesia. The keratoconic cornea is removed and a donor cornea (human tissue provided by the National Eye Bank after careful quality screening) is then sutured back in it's place. A prolonged period of post operative care is required to ensure the graft remains healthy.

Auckland Eye - New Zealand Centre of Excellence for Eye Care