People with Down's syndrome and their eyes

Research demonstrates that people with Down’s syndrome are at higher risk of having significant sight problems; many are correctable or treatable.  Information can be slow to reach service providers and carers, and there are still many people with Down’s syndrome not receiving regular eye checks or appropriate help for an eye condition.

When people do not have the necessary communication skills to explain to others that their eyes ‘don’t seem right’ there are many alternative ways that they may convey this.  For example, they may show fear or distress in certain situations, adopt unusual head positions or avoid tasks that involve close work.

Please refer to the Look Up Factsheet: 'Looking for eye problems in people with learning disabilities’.

It is very common for people with Down’s syndrome to be labelled as ‘difficult’, ‘disruptive’ or ‘lazy’ when in fact they have a sight problem and are experiencing even more difficulty understanding their unpredictable environments.  People are also frequently misdiagnosed as having Alzheimer’s as there is also an increased prevalence of this amongst people with Down’s syndrome, so it is crucial that a sight problem is identified and appropriate treatment or support offered.

This factsheet aims to provide readers with a brief overview of the problems individuals with Down’s syndrome may encounter with their eyes and sight.  It forms part of Look Up’s Factsheet range, which has been developed to give information on issues relating to vision to people who are involved in the support of people with learning disabilities.

It is anticipated that this Factsheet will not only highlight the increased risk of sight problems for people with Down’s syndrome but also introduce some ideas on what support people can be offered.  While it does not go into great depth in this area it is hoped that readers will obtain other, more detailed, factsheets from the Look Up Factsheet range.

How the eye works

 The eye works by light passing through transparent parts and projecting an image on the back of the eye (the retina).  Light initially passes through the cornea - the clear outer part of the eye.  The cornea bends (focuses) the light.  The light then travels through the watery fluid behind the cornea (the aqueous).

Behind the aqueous is the iris, the part that gives our eyes their colour.  At the centre of the iris is a hole called the pupil.  The iris either contracts or dilates to make the pupil smaller or larger, depending on the light.  It becomes smaller in bright light and larger in dim light.

Light is further bent through the lens, which is transparent, and changes its shape according to whether the object looked at is near or far.  The light is then projected onto the retina and the image is sent via the optic nerve to the brain for interpretation.  The macular is the most sensitive part of the retina and is responsible for fine vision tasks.  The rest of the retina provides peripheral (all round) vision.

Focusing errors, for example longsight and shortsight, are caused by light converging either behind or in front of the retina rather than on it.

Eye conditions more common amongst people with Down’s syndrome

The eye conditions described below can be found amongst people who do not have Down’s syndrome.  However, for reasons not always identified, evidence shows an increased risk of them occurring in children and adults with Down’s syndrome.

Refractive errors (the overall term used for conditions which affect focusing and are usually resolved by the person wearing glasses) are ten times more likely amongst people with Down’s syndrome than in the general population:

Longsight or hypermetropia

Longsight or hypermetropia results in the person having more difficulty in seeing things that are close up than far away, although both can be affected.  This condition can be corrected with prescription lenses.

Shortsight or myopia

Shortsight or myopia results in the person having difficulty in seeing things that are in the distance.  This condition can also be corrected with prescription lenses.

Astigmatism

Astigmatism occurs when the curve of the cornea is not symmetrical.  It can occur alongside longsight and shortsight and results in the person having blurred vision at all distances.

Astigmatism is treated with prescription lenses (glasses or contact lenses) that are designed to counteract the different curves of the cornea.

Presbyopia

This condition (literally ‘old eye’) affects all of us as we get older, whether we wear glasses or not in our youth.  The lens, which is flexible when we are younger, loses its ability to change shape so that focusing on near tasks becomes difficult or impossible.  Affecting most of us at around the age of forty-five, presbyopia may happen at a younger age in people with Down’s syndrome.  ‘Reading glasses’ or bifocals are usually prescribed, and it is important to remember that people who do not read may benefit from glasses for near tasks like crafts and puzzles and, of course, eating.

Nystagmus

Nystagmus is an involuntary movement of the eyes - usually from side to side, but sometimes the eyes oscillate up and down or in a circular motion.  This affects about 15% of people with Down’s syndrome, but it is not part of the syndrome and should be considered as a visual impairment that someone has in addition to Down’s syndrome.  Detail vision will be poorer if a person has nystagmus.

Most people with nystagmus are affected by factors such as stress, tiredness and unfamiliar surroundings, making eye movements greater and vision worse.  They are also likely to tire more easily due to the increased effort to concentrate on focusing.  People often adopt a certain head position or head movement that helps them maximise their vision and it is crucial that they be able to locate and position themselves wherever is most helpful.

For those people with literacy skills, reading can be slow although this should not be seen as having poor reading ability.  People should be given more time to complete tasks.  The size and density of lettering that is required will vary from person to person, and experimenting with colour contrast may help.

Mobility can be affected as some people can have difficulty with balance and depth perception, for example, the person may think a change in floor colour is a step.  Some people find scanning their environment very difficult, and safety when crossing roads may become an issue.

Unfortunately, there is no cure for nystagmus and little treatment has proved to be effective.  It is important that any other eye condition that is present is treated, for example a person should still wear glasses for shortsight, even though they will not help the nystagmus.

Squint or strabismus

Squint or strabismus is quite common amongst people with Down’s syndrome.  This condition arises because of a lack of muscle co-ordination between the eyes and causes them to point in different directions.  As a result of strabismus individuals may experience double vision, vision in one eye only, loss of depth perception and uncoordinated - appearing eyes.  Squints can often be effectively treated in children, however if the problem is left into adulthood it can be harder to rectify, as the person will have usually developed ways to compensate.

Cataracts

A cataract is a clouding of the lens.  It can cause the person to have one or more of the following: blurred vision, double vision, difficulty seeing in bright light and, most importantly, disabling glare when facing a light source.  Amongst some people with Down’s syndrome, the onset or worsening of a cataract brings about ‘behaviour that others find challenging’ as vision changes dramatically depending on the environment.  This behaviour may be their only way of telling supporters that something is very wrong.

The most effective treatment for cataracts is surgery to remove the lens.  While surgeons often choose to perform cataract surgery on people with Down’s syndrome under general anaesthetic, it can be carried out under local anaesthetic with some sedation.  The operation generally only takes about 45 minutes and involves a small cut in the top of the eye which is stitched afterwards.  The cloudy lens is removed and a plastic replacement implanted.  (Further information in the Look Up Factsheet: ‘Minimising problems in eye surgery for adults with learning disabilities’ and our ‘Eye surgery support plan’.)

On occasions, the surgeon may decide that the eye is unsuitable for an implant and the person will be prescribed either glasses or contact lenses instead.

The main issue around cataract surgery for a person with Down’s syndrome is supervision after the operation, to prevent eye rubbing.  (Further information in the Look Up Factsheet: ‘Eye poking and eye touching in people with learning disabilities’.)

Keratoconus

Please refer to the Look Up Factsheet: ‘Keratoconus in people with learning disabilities’.

Keratoconus literally means ‘conical cornea’.  The cornea is usually transparent and spherical, however in this condition the cornea stretches causing the tissue to thin and the centre to bulge.  The cornea is the main part of the eye responsible for focusing so a change in its shape causes distorted vision (usually a combination of myopia and astigmatism).  Other symptoms may include: sensitivity to bright light, double vision, difficulty adjusting to vision in differently lit environments and halos around images.

Keratoconus can progress at various rates and usually to different degrees in each eye.  The changes to the eye can stabilise after a few months or continue for many years.  In a small number of cases the cornea can become so fragile that the back surface ruptures allowing fluid in.  This condition is known as hydrops and can cause some pain and blurred vision.

Although keratoconus is a fairly rare condition and the cause unknown, evidence shows an increased risk amongst people with Down’s syndrome, people with a history of allergies such as asthma, eczema and hay fever, people who eye rub or eye poke, and South Asian and Afro-Caribbean people.

Management of keratoconus varies depending on its level of its progression.  In the early stages glasses may help, but the best management is with contact lenses, which can restore good vision.  Some health professionals may make the unfortunate assumption that people with Down’s syndrome are unable to cope with contact lenses, but there are increasing numbers of specialist optometrists who fit lenses.  Families and carers, as well as the person with Down’s syndrome, may need to be trained to insert and remove lenses.  (Further information in our Look Up Factsheet: ‘Contact lenses for adults with learning disabilities and keratoconus’.)

In very rare cases people require corneal surgery in which a corneal transplant is carried out.  (Further information in our Look Up Factsheet: ‘Corneal grafts for adults with learning disabilities’.)

Eye infections

Due to a number of factors, people with Down’s syndrome are often prone to various eye infections.  For example:

• they are known to have a decreased immune system
• they often have narrower than average tear ducts, which are tubes running from the corner of the eyes to the back of the nose, compromising drainage of tears and causing blockages
• they often experience dry skin around the eyes.

All of these factors can contribute to the development of infections such as conjunctivitis and blepharitis.  Blepharitis is very common amongst people with Down’s syndrome; this shows as small flakes of debris along the eye lashes, and sometimes red rims to the eyes.  It is easily managed by keeping eyes clean by bathing them.  Local optometrists/opticians can offer advice in most cases, and it is only the most persistent cases that require medical referral.  (Further information in the Look Up Factsheet: ‘Eyelid hygiene and applying eye ointment’.)

The following eye conditions are not known for having a direct link to people with Down’s syndrome but nevertheless should be highlighted.

Eye conditions related to diabetes

As there is an increased incidence of diabetes amongst people with Down’s syndrome then there comes an increased risk of the eye conditions associated with diabetes.  This may include:

Cataracts - see above for more details.

Temporary blurring - when a person develops diabetes they may have a period of blurred vision until the diabetes is under control.

Diabetic retinopathy - this is a condition that affects the blood vessels in the retina and can affect vision in a number of ways.

It is vital that people with diabetes have their eyes checked regularly.  Information about local services for people with diabetes should be obtained from the local Community Team for People with Learning Disabilities or person’s GP.

Eye conditions related to ethnicity

There is an increased risk of eye conditions amongst people from different ethnic groups, however research into eye conditions, ethnicity and Down’s syndrome is sparse.

Examples of such conditions are:

Glaucoma - more prevalent amongst Afro-Caribbean and Asian people.

Sickle cell disease - this disease can cause problems in the retina and is more prevalent amongst Afro-Caribbean and Asian people.

Lupus - this disease can cause light sensitivity and is more prevalent amongst Afro-Caribbean and Asian women.

CMV retinitis - this is an eye infection affecting people with AIDS or damaged immune systems, and is more prevalent amongst African people.

What can be done?

Regular eye tests

Please refer to the Look Up Factsheets: ‘Access to eye care for adults with learning disabilities’, ‘Eye tests for adults with learning disabilities’ and our ‘Telling the optometrist about me’ form and our ‘Feedback from the optometrist about my eye test’ form.

Given the high incidence of eye problems amongst people with Down’s syndrome, Look Up is campaigning for individuals to have their eyes checked annually.  However, most people only receive a free NHS eye test every two years.

There are two main assessments that are usually carried out by an optometrist:

• Eye health check

This is to confirm that the eyes are free from disease or damage and that both eyes are working together.

• Vision assessment

This is to establish how much an individual can see, whether they need glasses and to check their all round vision.

If a person is found to have a sight-threatening condition they should be referred by their optometrist or their GP to an ophthalmologist (eye doctor).

People with visual impairments also need:

• A functional assessment of vision

Please refer to the Look Up Factsheet: ‘Obtaining specialist support for people with sight problems and learning disabilities’.

This is to ascertain what useful vision someone has in order to carry out everyday tasks.  It should help establish such things as where to position objects, what lighting would best help someone, and what are useful colour contrasts to maximise sight.  A Rehabilitation Officer for Visually Impaired People from the social services department/social work department usually carries out this assessment, or local societies for visually impaired people may offer them.

Environment

Please refer to the Look Up Factsheet: ‘Adapting accommodation for people with learning disabilities and sight problems’.

If a person with Down’s syndrome is identified as having a visual impairment they will require adaptations to their environments in order that they make best use of their existing sight.  This area is usually tied in with a ‘functional assessment of vision’ (outlined above) and the local Rehabilitation Officer should be able to advise on this.  Alternatively advice can often be sought from a local society for visually impaired people.

Drops

Please refer to the Look Up Factsheet: ‘Eye drops for adults with learning disabilities’.

Due to the increased risk of eye infections amongst people with Down’s syndrome it is common for them to be prescribed drops.  Eye drops are also often required following eye surgery so it is worth including this in your plans for preparing the person.  Preparation for eye drops can be done using a simple saline solution (which does not contain preservatives), which can be obtained from a GP.  People also find eye drop dispensers very helpful and allow some individuals to insert their own drops.

Please contact RNIB’s Customer Services for details on eye drop dispensers, telephone 08457 023 153, and Minicom 08457 585 691.

Glasses

Please refer to the Look Up Factsheets: ‘Glasses for adults with learning disabilities’ and ‘Making sense of prescriptions for spectacles’.

Many of the eye conditions prevalent amongst people with Down’s syndrome are treated with glasses.  It is vital that those supporting the individual know what the glasses are for and understand that they will not help in all situations.  Many people require two sets and it can be helpful to have their purpose etched on the side of the frame, for example NV - near vision and LV - long vision.

People with Down’s syndrome can sometimes have difficulty in getting glasses to fit.  However, they are entitled as everyone else to glasses that fit securely and comfortably and look good.  It may take the optometrist/optician a little longer to find a suitable frame, and to make adjustments to bridge fitting and sides.

People with Down’s syndrome may also show initial reluctance to wear glasses.  It is important to remember that glasses change the way the world looks, and although we may think of clearer vision as better, to the person concerned, clearer may just mean ‘different’.  It is therefore crucial that glasses are introduced in a thoughtful way, ensuring that the person is encouraged to wear them for short activities that are motivating and where the benefits of wearing the glasses will be obvious.

People will be reluctant to use glasses if they are expected to wear them for tasks that the lenses were not designed for, or if the spectacles are dirty.

Surgery

Please refer to the Look Up Factsheets: ‘Minimising problems in eye surgery for adults with learning disabilities’ and our ‘Eye surgery support plan’.

An increasing number of people with Down’s syndrome have had successful eye surgery, especially cataract surgery.  This has greatly improved their quality of life.  Sensitive and carefully planned support must be available to them before, during, and after operations.

Some people may be at risk from general anaesthetics because they have severe health problems, such as a heart condition.  Advice from consultants and anaesthetists should be sought if this is the reason why surgery is refused or delayed.

Laser treatment

Laser treatment for refractive errors is on the increase although still only available on the NHS in the UK if the condition cannot be treated with glasses.  Generally people who have other eye conditions alongside a refractive error are not good candidates for laser treatment and there is some risk of the treatment being unsuccessful.  Laser treatment changes the shape of the cornea.  People with Down’s syndrome have thinner (and therefore more fragile) corneas than the general population, and for this reason, laser treatment is unlikely to be offered in most cases.

Conclusion

Given the incidence of sight problems amongst people with Down’s syndrome it is paramount that:

• All those involved in the support of someone with Down’s syndrome are aware of the increased risk of sight problems.
• All those involved in the support of someone with Down’s syndrome know how to access eye checks in their local area.
• All people with Down’s syndrome obtain regular eye checks - at least  every two years, or more frequently if the optometrist recommends it.
• All those involved in the support of a person with Down’s syndrome who has a sight problem should know the details of the condition.
• All those involved in the support of a person with Down’s syndrome should have an understanding of how they can adapt the environment and their own behaviour to meet the individual’s visual needs.
• All those involved in the support of a person with Down’s syndrome know how to use and maintain any specialist equipment (e.g. people know what tasks a specific pair of glasses should be used for).

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