Eye Conditions ( A - F )

Here you will see a list of eye conditions.  Look Up makes every effort to ensure the information we provide is correct - however we are not a medical website. We have provided links to other organisations should you need more detailed information about eye health and disease.

The eye conditions are separated alphabetically as follows:

A - F      Can be found on this page
G - N      Click here to go to this page
O - Z      Click here to go to this page

Amblyopia
Amblyopia refers to an eye that is healthy but does not see clearly or does not see in unison with the unaffected eye. Amblyopia is sometimes referred to as ‘lazy eye’. An amblyopic eye has reduced vision, often leading to people using their unaffected eye only.

Amblyopia has a variety of causes all of which reduce the quality of visual information reaching the brain in early childhood when vision is developing. Causes include anisometropia – a difference in power between the two eyes; astigmatism – a defect in focussing in the eyes; strabismus or squint – a condition where the eyes are incorrectly aligned and do not work together; and occlusion or deprivation caused by conditions such as a droopy eyelid, congenital cataract (a cataract present at birth), or damage and scarring to the front of the eye preventing clear focus.

Intervention for Amblyopia is often provided to children by an orthoptist who will devise strategies to ‘train’ the amblyopic eye to improve its movement and function.  An orthoptist is an eye care worker that specialises in the diagnosis and management of defective eye movement and eye muscles.

Amblyopia in people with learning disabilities may be difficult to detect – but may be characterised by people holding objects to their unaffected eye, or having difficulty in depth perception, or suffering poor vision when tired or overly visually stimulated.

If people, especially children and teenagers, have been prescribed glasses to help with their amblyopia it is important that they are encouraged to wear them whenever necessary. Young people may also be asked to wear a patch for a few hours per day and they should be encouraged to do this and perform interesting visual tasks whilst wearing the patch.

For people with communication difficulties it may be very difficult for them to tell you how they see their world. It requires skilled observation and good knowledge of the person to begin to understand how a person might be seeing their world. A functional vision assessment is an important method of assessing someone’s vision.

For more information click here to visit the NHS Choices website.


Aniridia
Aniridia refers to having part or all of the iris missing. The iris is the coloured ring of the eye. The main function of the iris is to regulate the amount of light that enters the eye, and to improve the accuracy of the focussing of the eye. The degree to which someone’s vision may be affected by aniridia depends upon the severity of the condition. People are born with aniridia and may develop other eye conditions that will further impair their sight. Other eye conditions associated with Aniridia may be infantile glaucoma (Buphthalmos), nystagmus, cataracts or strabismus. People may also develop problems with their cornea (the transparent window on the front of the eye).

People with aniridia will suffer from sensitivity to light – photophobia – and will benefit from sunglasses or sun shades, people may also suffer from headaches and headaches as a result. Some people with this condition may be fitted with tinted contact lenses to alleviate their symptoms and improve their vision.

For people with communication difficulties it may be very difficult for them to tell you how they see their world. It requires skilled observation and good knowledge of the person to begin to understand how a person might be seeing their world. A functional vision assessment is an important method of assessing someone’s vision.

For more information click here to visit the Aniridia UK network website.


Blepharitis
Blepharitis is a condition where the eyelids become inflamed (red and swollen), It can cause
•burning, soreness or stinging in the eyes
•crusty eyelashes
•itchy eyelids
It is not contagious.

It may also cause dry eyes.

Blepharitis may occur more frequently in people with Down’s Syndrome. Supporters and carers should encourage good eye hygiene, following guidance from their optometrist (optician),  a nurse or GP. In rare cases Blepharitis might lead to more serious damage to the eye and this maybe more likely to occur in people with learning disabilities as they may not receive the intervention the condition requires. People who persistently rub their sore, itchy or very dry eyes should have their eyes examined by an optometrist or consult their GP. 

For more information click here to visit the NHS Choices website. See also http://www.lookupinfo.org/eye_care/eye_care_factsheets/eye_lid_hygiene.aspx


Cataract
A cataract is the clouding of the part of the eye called the lens.
The lens is normally transparent, and provides one third of the focussing power of the eye. It is flexible in most people under 40 allowing accurate focussing of light on to the retina from objects at different distances from the eye. . The lens is important in refracting (bending) light so it reaches the retina. The retina is the light sensitive layer at the back of the eye. Vision becomes blurred because the cataract which causes clouding of the lens distorts or blurs the image reaching the retina.

The impact of a cataract upon vision depends on the thickness or density of the cataract and it position within the lens. If the cataract is dense and is within the centre of the lens then a person will have a more serious visual impairment than if the cataract is thinner and at the edge of the lens.

Commonly cataracts occur in later life, although they may be congenital (present at birth) and occur in children or sometimes in younger adults.

It is known that people with Down's syndrome are be more likely than others to develop cataract, and they may do so at a younger age. Other conditions such as diabetes may cause cataract to develop earlier, and certain medications such as steroids can also cause cataracts to develop. Regular eye examinations will identify if someone is developing a cataract. Cataracts can be removed through surgery and this surgery is available to people with learning disabilities.

For people with communication difficulties it may be very difficult for them to tell you how they see their world. It requires skilled observation and good knowledge of the person to begin to understand how a person might be seeing their world. A functional vision assessment is an important method of assessing someone’s vision.

Visit the SeeAbility website to see a simulation of the impact of having a cataract or download our easy read factsheet on cataracts 


Cerebral or Cortical visual impairment

Sight occurs as a result light being focussed by the eye on to a light sensitive layer, the retina, which is located at the back of the eye. The retina converts the light energy into nerve impulses which are then transmitted down the optic nerves to make connections in the brain. Most of the nerve fibres connect to the visual cortex which is located in the occipital lobe at the back of the brain. Within the visual cortex there are areas dealing with facial and object recognition, motion and size perception and many different centres allowing us to start to make sense of the raw nerve impulses from the eyes. These centres within the visual cortex in turn make millions of connections throughout the rest of the brain allowing us to see objects, understand where and what they are, interact with our environment, communicate and move through visual space.

Cortical or Cerebral visual impairment (CVI) occurs when areas of the brain concerned with visual processing are damaged by disease, injury, trauma or mal-development. It may also occur if the optic nerve or other visual pathways within the brain are damaged. Many people with profound multiple learning disabilities may have cortical visual impairment, as may people with Cerebral Palsy, Hydrocephalus, microcephalus or people who have experienced head injury or stroke. The impact upon sight can be total blindness or complex vision loss where some facets of sight may be affected (such as seeing movement, recognising objects or faces).

For people with communication difficulties it may be very difficult for them to tell you how they see their world. It requires skilled observation and good knowledge of the person to begin to understand how a person might be seeing their world. A functional vision assessment is an important method of assessing someone’s vision.

For more information about cortical or cerebral visual impairment visit the Scottish Sensory Centre website at http://www.ssc.education.ed.ac.uk/home.html


Coloboma
Coloboma is a developmental defect of the eye, most commonly affecting the iris, the coloured 'ring around the pupil'. Coloboma can also affect all parts of the eye including  the lens, retina and choroid. It often leads to the iris resembling a key-hole in shape. The iris controls the amount of light that can enter the eye. The iris opens or closes to regulate light entering the eye, so people with iris coloboma may experience unpleasant glare. If other parts of the eye are affected then more serious sight problems might occur.
Coloboma may occur as part of a syndrome that may also include learning disability, for example CHARGE. CHARGE is a rare condition that stands for:

C - Coloboma
H - heart defects
A - atresia of the choanae (problems with the nose passages)
R - retarded growth and developments
G - genital hypoplasia (un-descended testicles)
E - ear abnormalities.

For people with communication difficulties it may be very difficult for them to tell you how they see their world. It requires skilled observation and good knowledge of the person to begin to understand how a person might be seeing their world. A functional vision assessment is an important method of assessing someone’s vision.

Click here to visit the CHARGE syndrome website 

Click here for more information from the RNIB on Coloboma


Corneal Opacities
The cornea is the clear transparent window at the front of the eye. Any loss of transparency of the cornea will result in an impairment of vision because the opacity or clouding of the cornea will prevent light entering the eye. Injury (such as persistent and severe eye poking), scarring to the front of the eye, corneal ulcers, and eye diseases such as keratoconus or corneal dystrophy will cause the cornea to become unclear or affect its normal function. Corneal opacities may also be caused by developmental defects. The impact upon vision will depend on the severity of the corneal opacity. There is a range of treatment for corneal opacities ranging from eye drops to corneal grafts. Supporters and carers should remain vigilant and advise people to visit their optician or GP if they observe that someone's cornea starts to appear sore, ulcerated, cloudy or milky.

For people with communication difficulties it may be very difficult for them to tell you how they see their world. It requires skilled observation and good knowledge of the person to begin to understand how a person might be seeing their world. A functional vision assessment is an important method of assessing someone’s vision.

For more information about Corneal Grafts see our booklet

Click here to visit the RNIB website for information about the cornea and corneal disease


Detached Retina
The retina is the light sensitive layer lining the back of the eye. It converts light energy into nerve impulses, and requires good blood flow and nutrition. Most of this nutrition is supplied by the underlying choroid – a layer of the eye containing numerous blood vessels and capillary networks. If the light sensitive retina is separated from the choroid it is unable to function properly and this is termed a retinal detachment. These layers may become separated due to fluid leaking under the retina causing it to peel away from the choroid, fibrous scar tissue shrinking and pulling the retina away from the choroid, or tumours or cysts pushing the retina away from the choroid. Retinal detachment may be caused by injuries such as blows to the head or eyes, eye poking or head banging. Some individuals such as those who are very short-sighted (highly myopic) or who have conditions such as diabetes may be more likely to develop a retinal detachment. People who have had cataract surgery or other eye surgery may also be at higher risk of developing a retinal detachment. When the retina becomes detached it is is unable to send information to the brain and this leads to loss of vision. A detached retina may lead to patchy vision, visual field losses or in some cases total loss of sight. The degree and extent of visual loss depends on where the retina becomes detached within the eye, how much of the retina detaches and how quickly it is detected and treated.

People often see 'floaters' in their vision - these are bits of debris within the eye which cause shadows on the retina as light enters the eye and they are relatively common. However, new or persistent 'floaters' may demonstrate a more serious retinal problem and should be investigated to rule out retinal detachment. If someone complains of seeing flashing lights as well as new floaters or any loss of vision they should be examined by an eye care professional immediately.

Carers and supporters may need to take action if people complain frequently about having 'something in their eye' or something that 'floats around in their eye'. People who may self injury may target  their head or eyes, or people who may vigorously and persistently ‘eye poke’, and  may need close supervision by skilled staff. People will need regular eye checks to monitor any damage that might be caused. Detached retinas are painless although the impact of sudden sight loss may cause distress or anxiety. Carers should be alert to any changes in behaviour which could be related to sudden sight loss and arrange examination by a suitable eye care professional immediately.

Treatments for retinal detachment include laser therapies or surgical interventions.

For people with communication difficulties it may be very difficult for them to tell you how they see their world. It requires skilled observation and good knowledge of the person to begin to understand how a person might be seeing their world. A functional vision assessment is an important method of assessing someone’s vision.

Click here to visit the RNIB website for more information on retinal detachment.


Diabetes related eye conditions
People with Diabetes type 1 (used to be called juvenile onset or insulin dependent diabetes) or type 2 (used to be called non-insulin dependent or maturity onset diabetes) are at risk of developing sight problems. Research has found that early treatment, regular screening and maintaining a healthy lifestyle can prevent severe vision loss in 90% of cases of diabetic eye disease (nhs direct).

There are different types of eye problems caused by diabetes, and they mostly affect the retina. The retina is the light sensitive layer of the eye, and it lies at the rear of the eye. The retina responds to light focussed upon it by turning light into nerve impulses that are sent from the retina along the optic nerve to the brain. The area of the retina called the macular is the area that is especially sensitive to seeing in detail, reading, recognising faces, and seeing in colour. The sight we receive from the macular is often referred to as our central vision.

Background Diabetic retinopathy is a very common condition in which the tiny blood vessels in the retina are swollen or damaged. However with this condition sight is often unaffected. When the central part of the retina, the the macular is affected then the person may experience some difficulties with seeing details and seeing clearly. When the macular is damaged by diabetes this is called Diabetic Maculopathy.

The best treatment to prevent both background diabetic retinopathy and diabetic maculopathy is good control of the diabetes by maintaining good blood sugar control, good control of blood pressure, and maintaining good control of cholesterol. Smokers are also at higher risk of developing these conditions and should seek support from their doctor (GP) or diabetic nurse to stop smoking.

Proliferative diabetic retinopathy can occur if the control of diabetes is poor, or if someone has been diabetic for many years. It can also occur when someone with diabetes becomes pregnant. In proliferative diabetic retinopathy new, abnormal blood vessels grow in the back of the eye. These vessels often leak or bleed damaging the retina and in turn causing problems with vision. The sight loss in this condition is often gradual and may go unnoticed, but may be sudden if a large bleed (haemorrhage) occurs. Retinal detachment may also occur if the new blood vessels form scar tissue and pull on the retina. Diabetic retinopathy can lead to irreversible loss of sight or even blindness if is not detected and treated early.

Proliferative diabetic retinopathy is treated with a laser by an eye doctor (ophthalmologist). Sometimes eye surgery or other treatment is also needed. Good control of diabetes is also important.
People with diabetic eye disease are at risk of developing cataracts and glaucoma.
Because diabetic retinopathy may not cause any symptoms it is important that anyone who is diabetic has their eyes examined every year to detect any changes as early as possible.

People with learning disabilities are as much as risk of developing diabetes as any one else, however due to poor understanding may manage the condition less well and also be less able to communicate when things are going wrong or they feel unwell . People with diabetes should be offered an annual specialist diabetic eye screening appointment. It is vital that carers and supporters encourage people to attend this annual eye screening appointment. If they have not been invited for this screening they, their carers or supporters should contact the GP to arrange this. Support should also be given to ensure they are encouraged to manage their diabetes as directed by their GP or diabetes nurse.

For people with communication difficulties it may be very difficult for them to tell you how they see their world. It requires skilled observation and good knowledge of the person to begin to understand how a person might be seeing their world. A functional vision assessment is an important method of assessing someone’s vision.

For further information click here to see our factsheet on diabetes and eye health
For further information about Diabetes visit the Diabetes UK website

Errors of Refraction
In order to see clearly and in focus, light needs to be bent (refracted) by the cornea (the clear window on the front of the eye) and the lens which is situated just behind the iris (coloured part of the eye) and pupil (the black hole in the iris). The light is refracted so it is focussed upon the retina. The retina is the light sensitive layer at the back of the eye. A refractive error means that the cornea and lens do not bend the light accurately enough for a clear image to be formed on the retina. This means, depending on the type of error of refraction you have, certain images will be blurred.
The main errors of refraction are:
Myopia – short sight. In myopia images of far away objects will be blurred and those of nearer objects will be in focus. People who are very myopic (high myopia) are at risk of retinal detachment and other eye problems.
Hypermetropia - longsighted or farsighted. Hypermetropia means that nearer objects will be blurred whilst objects further away will be in focus. When we are young low degrees of hypermetropia can be compensated for using the focussing power or accommodation of the eye. As we get older this ability declines and vision may need to be corrected using glasses or contact lenses.
Astigmatism. Astigmatism is caused when the cornea or lens of the eye are not equally curved in all directions. Instead they may be flatter in one direction than another like the surface of a teaspoon, rugby ball or hens egg. This difference in curvature prevents images from being accurately focussed on the retina. This can affect the way we see objects which are both near and far away.
Presbyopia – After the age of about 40 the eye loses its ability to focus (also known as accommodation) on near images. This means that it gets harder to perform near tasks such as reading, eating or recognising images close to us. Presbyopia occurs alongside other refractive errors.
Errors of refraction are disorders not diseases and are treated or corrected by spectacles or contact lenses. Regular eye examinations by an optometrist will identify and monitor refractive errors. Errors of refraction are often treated through the prescription of spectacles or contact lenses.

People with learning disabilities are more likely to have errors of refraction, especially higher degrees of refractive error. It is important that people have regular eye checks to monitor their eye health and any refractive error they may have. It is important that people wear their glasses – and it is equally important that carers and supporters encourage people to wear glasses as prescribed by the optometrist.

For people with communication difficulties it may be very difficult for them to tell you how they see their world. It requires skilled observation and good knowledge of the person to begin to understand how a person might be seeing their world. A functional vision assessment is an important method of assessing how some one may be seeing their world.

For more information see our easy read fact sheets about eye tests.