Kiwis have a range of conditions which lead to sight loss – some are common and others rare.
The most common are macular degeneration, retinitis pigmentosa, glaucoma, diabetic retinopathy and cataracts. On this page, you’ll find information on other conditions which may lead Kiwis to register with the Blind Foundation.
If you’d like to know more about a condition and can’t see it here, we might be able to help. Please get in touch on 0800 24 33 33 or firstname.lastname@example.org
Albinism is a condition where people have little or no melanin pigment in their eyes, skin or hair. As development of the optical system is dependent on melanin, it means that people with albinism can have low vision. You can find out more at New Zealand’s Albinism Trust.
Charles Bonnet Syndrome
Charles Bonnet Syndrome
Charles Bonnet was a Swiss naturalist who lived over 250 years ago. He began to lose his eyesight in his early thirties and started to see vivid images of people and objects he knew were not there. His grandfather had also noticed similar symptoms when he became blind from cataracts.
Around 30% of new clients to the Blind Foundation admit to the hallucinations.
What causes Charles Bonnet Syndrome?
The cause is not fully understood. The hallucinations are generally noticed by people who have lost their sight later in life due to glaucoma, macular degeneration or diabetic retinopathy but can occur at any age and following any cause of vision loss.
One theory is that sight stops the brain from producing its own images, when sight is lost the brain fills in the gaps with images it has stored. Another theory is that the damaged visual pathway releases defective impulses causing the hallucinations.
What are the symptoms of Charles Bonnet Syndrome?
People who have Charles Bonnet Syndrome are aware the images are not real.
Visual hallucinations are seen repeatedly, often on waking.
The hallucinations can be simple patterns or complex landscapes; they may be animals or people.
The images may work with the surroundings such as seeing cows when looking at a field or can be complete fantasy and not fit with the environment.
The images may be still or appear to move across your vision.
The images are generally not of threatening scenes but when first seen people are understandably frightened by them.
With time people can even find the images enjoyable and be amused by them.
Each hallucination may last a few minutes or a few hours.
They often reduce in frequency within 18 months of them first appearing but can continue to be apparent 5 years on.
There have been cases where a stressful life event can change the images to become distressing but this is unusual.
Can Charles Bonnet Syndrome be treated?
There is no cure for the hallucinations but often talking about them and learning that they are a common association with sight loss can be helpful. Knowing that they are due to your vision loss and not a mental health issue is of course reassuring to the sufferer and their family.
Awareness of the condition is slowly improving amongst healthcare professionals. People can be reluctant to talk about the hallucinations due to fears and misunderstanding but it is important to discuss it with your eye health care provider as the more information that can be gathered the more is learnt about the condition.
A printable PDF download of this information – Charles Bonnet Syndrome
Useful further information:
Cortical Visual Impairment (CVI)
Cortical visual impairment (CVI) is used to describe a visual impairment that occurs due to brain injury. Rather than being a physical problem with the eye, it is caused by damage to the brain. It means the eyes can see but the brain is not interpreting what is being seen.
Often keratoconus can initially be treated with glasses or contact lenses. Once vision can’t be improved with glasses or contact lenses, surgery might be needed.
Nystagmus is an involuntary repetitive movement of the eyes. It is usually a side to side movement but can be up and down or even a circular motion.
People with early onset nystagmus do not usually notice the movement of their vision.
Nystagmus is believed to affect approximately 1 in 1000 individuals.
What causes nystagmus?
For many children with nystagmus there are no other health problems.
When the cause is unknown and it starts early in life it is referred to as idiopathic infantile nystagmus.
Nystagmus may be caused by a problem in the eye, along the visual pathway between the eye and the brain or the area of the brain that controls eye movement.
Nystagmus may be inherited, with other members of the family having a similar condition or it could be an isolated case.
Nystagmus in childhood may be associated with:
Albinism (a genetic disorders that causes the skin, hair, or eyes to have little or no pigment)
Aniridia (an eye disorder characterized by a complete or partial absence of the coloured part of the eye, the iris)
Optic nerve hypoplasia (a congenital condition in which the optic nerve has not developed properly; it is too small)
Congenital cataracts (a clouding of the lens of the eye that is present at birth)
Acquired nystagmus develops later in life and may be a symptom of another condition such as a head injury, a stroke or multiple sclerosis. It may be a side effect of some medications. In these acquired cases the movement of the eyes can cause oscillopsia where the person is aware of the moving images.
When nystagmus is noticed either in early childhood or for the first time later in life it is important to be referred to an ophthalmologist or neurologist as the cause will need to be investigated.
What are the symptoms of nystagmus?
The symptoms vary from person to person.
The vision will most likely be reduced, the degree of vision loss is hard to predict and can depend on the cause of the nystagmus.
Vision can be variable and affected by the environment, how tired the person is and lighting levels.
Reading speed may be affected and people may benefit from using larger print or magnifying aids. It is important to remember this is due to their vision problem and not necessarily developmental delay.
A person with nystagmus may turn their head to look at what they are focusing on. This is because they are using a null point, a position of the eyes where the movement is reduced and vision is therefore improved. They can be helped to use this by sitting in a particular place in the classroom. They should be allowed to use this head posture as it is helping them achieve their best possible vision.
The nystagmus may affect a person’s confidence and make it difficult for them to maintain eye contact.
Can nystagmus be treated?
There is no cure for nystagmus but there are ways to help.
A person with nystagmus may also need glasses and although this will not stop the nystagmus if they are prescribed they should be worn. Glasses are needed to help focus the light onto the retina (the light sensitive layer at the back of the eye) when the eye is not the correct length or shape. Contact lenses can be an alternative to glasses for some people.
For some people with nystagmus surgery to the muscles that control the movement of the eye can relieve the need for them to use an head posture and help them use the null point in a more comfortable and effective way.
Keeping up to date with appointments with the eye specialists will mean you can access the best treatments. Glasses prescriptions can change and need updating every 1 to 2 years.
Your eye specialist (ophthalmologist or optometrist) may refer you to services such as the Blind Foundation or BLENNZ (Blind and low vision education network NZ). Through these you will have support at school and at home to have access to the same opportunities as those without vision problems.
A printable PDF download of this information – nystagmus (.pdf)
Useful further information
Retinal detachment is when the retina peels away from the back of the inside of the eye. It is considered a medical emergency which needs to be treated straight away.
Symptoms include floaters (bits of debris in your eye which may be harmless), sudden loss of vision, flashing lights or dark shadows across your vision. You should seek medical advice straight away if you experience these.
One cause of retinal detachment is trauma to the eye. So wear protection for DIY, gardening or any high impact or high speed sports.
Regular eye tests are the best way to make sure your eyes are healthy.
Stargardt disease can also be known as fundus flavimaculatus and Stargardt macular dystrophy.
Stargardt disease is an inherited condition that affects the macular. It is a form of juvenile macular degeneration.
It affects around 1 in 10,000 people.
The retina is the light sensitive layer on the inner wall of the back of the eye. The macular is the area on the retina which we use for detailed vision such as reading.
As the macular is the area which is most affected, it is the central vision (the vision you use when looking directly at something) that becomes reduced. Stargardt disease does not usually affect peripheral (side) vision.
Stargardt disease is generally diagnosed before the age of 20 years. Children typically begin to experience central vision loss between the age of 6 and 12 years of age but occasionally the first symptoms may appear in adulthood.
What are the symptoms of Stargardt disease?
A child may first present to the optometrist or ophthalmologist due to a reduction in central vision or difficulty with reading and seeing in dim light.
They may describe blurriness or distorted vision.
The central vision also gives us our best colour vision and a decrease in colour perception may be noticed.
People may notice grey, black or hazy spots in the centre of their vision.
The progression of the disease can be variable; at first it may be slow but then can rapidly decrease.
The vision loss cannot be corrected with glasses, contact lenses or refractive surgery.
The visual acuity (this is what is tested when you read down a letter chart at the optometrist) will become reduced. The average visual acuity of a healthy eye is often written as 6/6 this means at 6 meters a person is seeing what would be expected to be seen at 6 meters. At the age of 50 a person with Stargardt disease may have visual acuity in the range of 6/60 – 6/120 (seeing at 6 meters what would be expected to be seen at 60 to 120 meters).
What causes Stargardt disease?
Stargardt disease is usually due to autosomal recessive inheritance of a mutation in the ABCA4 gene.
Each cell in the human body contains about 25,000 to 35,000 genes. Genes carry the information that determines which features or characteristics are passed on from your parents.
Genes come in pairs. Each of your parents has two copies of each of their genes, and each parent passes along just one copy to make up the genes you have.
Stargardt disease is recessive which means you need to receive the faulty copy of the gene from both parents. Often the parents are unaffected and are called carriers as they only have one copy of the Stargardt gene. Each of their children will have a 25% chance of inheriting the two copies of the gene.
The ABCA4 gene makes a protein that clears away a by-product of normal cell function called lipofuscin. The photoreceptor cells of people with Stargardt disease accumulate lipofuscin which is a fatty substance that forms yellow flecks stopping the cells from working properly.
How is Stargardt disease diagnosed?
Early in the disease the macular may appear normal making it difficult to diagnose but in time yellowish flecks can be seen in the macular. A photo and a scan may be taken of the macular in order to look for these signs.
Can Stargardt disease be treated?
UV blocking sunglasses are often recommended to offer some protection.
Now that the gene which is responsible has been discovered research is being done into possible gene therapy and also stem cell treatment but there is no treatment available at this time.
What can be done to help?
Low vision aids can be helpful for many daily tasks and lighting is also important. The learning and working environment needs to be adapted to allow both children and adults reach their full potential despite the challenges Stargardt disease presents.
A printable PDF download of this information – Stargardt Disease
Some people have problems with their vision after having a stroke.
Visual problems are more common when you suffer a stroke affecting the right side of your brain. The stroke damages the brain and impacts the visual pathways to your eye and cause vision loss, blurry vision, double vision or moving images.
Every stroke is different.