Factsheets Keratoconus

Introduction

This is a three part factsheet about keratoconus.  In this factsheet we will talk about what keratoconus is and how it might effect a person's vision. Part 2 and Part 3 will look at treatments and interventions.

Keratoconus literally means "a cone-shaped cornea".

The cornea is the clear window at the front of the eye through which you can see the pupil (the round black part of the eye) and the iris (the coloured part of the eye).  Keratoconus occurs when the transparent,  dome-shaped cornea becomes more pointed due to the thinning of the layers near the centre.

Treatment for keratoconus may be complicated and last a lifetime. 

Many people with keratoconus will always have low vision even if the treatment they receive is ‘successful’.  However, with the right help, people with learning disabilities and keratoconus can continue to live full lives.

Causes of keratoconus

The causes of keratoconus are unclear.  Up to 50% of keratoconus in ‘the general population’ occurs in families with a history of allergies, hay fever, eczema and/or asthma.  However, the following conditions have all been associated with the condition: 

• Down’s syndrome
• Marfan’s syndrome
• Turner’s syndrome
• Ehler’s Danlos syndrome
• Apert’s syndrome
• Aniridia
• Osteogenesis imperfecta

 Keratoconus is also associated with:

• Eye poking
• Eye rubbing
• Poor hygiene
• Recurrent eyelid infections
• Allergic skin conditions

How keratoconus progresses

Keratoconus is a progressive condition that usually starts at puberty.  Its rate of progress varies considerably.  It may stabilise after a short time or lead to significant sight loss and distortion of vision.  Keratoconus does not normally cause blindness.  However, we have heard of people whose sight loss has been caused by unsuccessful operations for keratoconus.

Hydrops

As keratoconus progresses, a condition called hydrops may occur.  Hydrops happens when the back surface of the thin cornea ruptures, letting fluid waterlog the cornea itself  (this swelling is also called oedema).

Hydrops appears as a cloudy, white or hazy grey patch across the pupil (the round black part of the eye).  It may also spread across the iris (the coloured part of the eye).  This implies a serious loss of vision that can be permanent if not treated urgently.

Most people with keratoconus will not get hydrops, but it is especially important that staff and family carers are aware of it and actively look for it in people with limited communication skills.  Changes in behaviour may be their only way of telling staff and carers about changes in their vision.

When hydrops occurs, the eye may become red, sticky or watery.  It is therefore crucial that:

• People with keratoconus, with any of these symptoms get immediate treatment at the local eye hospital casualty department
• Hospital staff are told that the person has keratoconus
• Treatment is not delayed because the person’s symptoms are attributed to another eye condition, such as conjunctivitis.  This may cause further sight loss 

Treatment in the form of saline eye drops may be offered.  These drops usually need to be used for two to three months.

How does Keratoconus affect vision?

Keratoconus affects each person differently.  Commonly reported visual symptoms include:

• problems with ‘glare’ (finding light painful and/or disabling - not just bright lights)
• double vision (often confusing or embarrassing)
• multiple images (which people find very troublesome)
• ‘ghosting’
• ‘halos’ and ‘stars’ around lights
• ‘floaters’ - black dots floating across vision
• Difficulty adapting to changes in light levels.  

In addition people with keratoconus may find that distortion of vision causes :

• difficulties in judging depth and distance
• problems on stairs, or coping with changes of level underfoot
• blurring of straight lines - one person may look at the letter H and see the verticals (the strokes which go up and down) clearly but find the horizontal stroke (which goes across) blurred.  Another person may see the reverse, and yet others may see what looks like a letter N.  This can cause problems in a world full of straight edges. 

Where people have corneal scarring they may have patchy vision - often with central vision damaged.

The effects of keratoconus (and other sight conditions) can vary throughout the day, and may be influenced by a variety of factors - such as tiredness, ill health, bright sunlight, lighting and other environmental factors.

Most people find it hard to describe exactly what they are seeing to another person.  Supporters of people with learning disabilities should listen to what they are saying about their vision, and question them carefully.

Eye rubbing and keratoconus

There is some evidence that keratoconus can be caused by excessive eye rubbing or eye poking.  It is unclear whether this aggravates corneal deterioration, or is a symptom.

Treatments and interventions

Keratoconus does not usually cause total blindness.  But it may severely distort vision. 

There are variety of treatments and interventions that are used for people with keratoconus, which include: 

• Wearing glasses
• Wearing contact lenses
• Intacs
• Collagen Cross Linking
• Corneal graft

June 2009 

For further information on this topic please read:

Treatments and Interventions for Keratoconus 2

Treatments and Interventions for Keratoconus 3

Related Information:

Adapting Accomodation for People with Learning Disabilities

Consent to Medical Treatments

The Need for an Eye Examination

Eye Poking and Touching in People with Learning Disabilities

Eye Poking and Touching - Strategies and Supporting People

Glaucoma

Recognising Eye Problems in People with Learning Disabilities 1

Recognising Eye Problems in People with Learning Disabilities 2

Supporting People to use their Sight Effectively

Taking Action on Eye Problems