Exploring common causes of sight loss  

According to the World Health Organisation (WHO), most people will experience at least one eye condition during their lifetime.

There are a number of common - and rare - conditions that can affect vision and can lead to visual impairments.

• In the UK, there are over 2 million people living with sight loss and of these, 340,000 people are registered blind or partially sighted. (RNIB)
• In the USA, approximately 6 million people are partially sighted and 1 million people are blind. (CDC)

It is important to recognise that sight loss is a spectrum and subsequently, blindness is not a singular experience. For some people, the vision may be obscured, for others it's blurred or double-vision and for others still, there may be a central 'tunnel' vision or they may see only with peripheral vision. 

Did you know that only around 10 - 15 percent of people who are registered blind have no vision at all? (Perkins School for the Blind) 

Here, we explore a wide spectrum of causes of sight loss, from common eye diseases including glaucoma and cataracts to much rarer sight loss conditions such as stargardt disease or retinopathy of prematurity.

Each of these sight conditions comes with a unique set of challenges. So as we explore what each condition is, you can find out more about the variations in the same conditions, the symptoms of common eye conditions, and how someone with that condition might view the world around them. Use the articles linked to from this page, to read more information on diagnosis, treatment and living with different sight conditions and find places that offer support and further information on each sight loss condition, both medical and charitable.

In addition, we explain how different assisitive technology products from Dolphin Computer Access empower people who are blind or partially sighted to live, study and work independently.  

Glaucoma

Glaucoma, is a group of eye disorders where pressure in the eye is high enough to cause damage to the optic nerve. Typically caused by elevated intraocular pressure (pressure in your eye), damage from glaucoma can lead to irreversible vision loss if left untreated.  'Secondary Glaucoma' can also occur as a result of another eye condition, an injury to the eye itself or sometimes due to medication (RNIB). 

Glaucoma often develops slowly and without noticeable symptoms until vision loss is advanced. There are some warning signs and symptoms which may indicate glaucoma, so it is important to keep to eye appointments and checks.

Symptoms of Glaucoma include:

• Gradual loss of peripheral vision.
• Tunnel vision in advanced stages.
• Eye pain or redness (in acute angle-closure glaucoma).

Treatment of Glaucoma include:

• Medications to lower intraocular pressure.
• Laser therapy
• Surgical procedures

Treatment will depend on the type and stage of glaucoma.

For more information on the symptoms, diagnosis and treatment of glaucoma, and advice on where to find further information, advice and assistive technology, please visit the article Focus on Glaucoma

Albinism

Albinism is a genetic condition that affects the production of melanin, leading to a lack of pigmentation in the skin, hair, and eyes. This is 'Oculocutaneous Albinism'. People with albinism have little to no melanin in their retinas, which often results in visual impairment, where the albinism primarily affects the eyes, this condition  is referred to as 'ocular albinism.'

Symptoms of eye conditions caused by Albinism include:

• Nystagmus (involuntary eye movement)
• Strabismus (misalignment of the eyes)
• Photophobia (sensitivity to light)
• Reduced visual acuity

Treatment of Albinism

• Visual aids such as tinted lenses
• Dark glasses to avoid glare and eye discomfort
• Ophthalmologic care for related conditions such as strabismus or nystagmus

Learn more about the symptoms, diagnosis and treatment of Albinism, along with further information, advice and assistive technology suggestions at Focus on Albinism

Cataracts

Cataracts are a common cause of vision impairment, particularly in older people, as they are a normal part of ageing. A cataract is a clouding of the eye's natural lens, which can obstruct light and result in blurred vision. Cataracts are the leading cause of blindness in middle and low-income countries, it affects millions of people around the world.

Symptoms of Cataracts

• Blurred, hazy or misty vision
• Increased sensitivity to light glare
• Difficulty with night vision
• Fading of colours

Treatment

Treatment for cataracts usually involves a quick surgery to remove the cataract - the cloudy lens of the eye - replacing it with an artificial lens. 

Learn more about the symptoms, diagnosis and treatment of cataracts, along with further information, advice and assistive technology suggestions in the article Focus on Cataracts

Macular Degeneration

Age-related Macular Degeneration (AMD) is a leading cause of vision loss among older adults. It affects the macula, a small area near the center of the retina responsible for sharp central vision. While AMD is the most common type of macular degeneration,  macular disease can affect people of any age, and it affects nearly 1.5 million people in the UK, and 19.8 million Americans over the age of 40.   

Symptoms

The symptoms of macular degeneration depend on the type of macular degeneration - these are Dry Macular Degeneration and Wet Macular Degeneration - and the stage of the macular disease. Common symptoms include:

• Blurred or distorted central vision
• Loss of central vision or 'blind spots'
• Difficulty recognising faces or reading
• Visual hallucinations caused by Charles Bonnet Syndrome
  
• Colour fading or reduced colour contrasts

Treatment

• For Wet AMD, anti-VEGF medications block growth of blood vessels
• Laser therapy on abnormal blood vessels in the eye
• For Dry AMD, nutritional supplements help slow the AMD progression
• Low vision aids and assistive technology assist with daily tasks

Learn more about the symptoms, diagnosis and treatment of Age-Related Macular Degeneration, along with further information, advice and assistive technology suggestions in the article Focus on AMD

Nystagmus

Nystagmus is a condition characterised by involuntary, rhythmic eye movements. These eye movements are usually side-to-side, but can be up and down or circular. A person with Nystagmus has no control over this eye movement. It can result in reduced vision due to the constant movement of the eyes. 

Nystagmus is a common symptom of other sight loss conditions, including albinism, congenital cataracts and myopia or astigmatism. It can also be a symptom caused by other conditions such as MS, stroke or inner ear inflammation, or a side effect of certain medications. 

Symptoms

• Involuntary eye movements (horizontal, vertical, or rotary)
• Blurred vision
• Sensitivity to light
• Difficulty seeing in low-light conditions
• Dizziness or balance and coordination difficulties

Treatment

• Correcting underlying causes, if possible eg. treating medical conditions
• Visual aids and rehabilitation to help adapt to reduced vision
• Assistive technology to aid reading and computer use

Learn more about the symptoms, diagnosis and treatment of Nystagmus, along with further information, advice and assistive technology suggestions in the article Focus on Nystagmus

Keratoconus

Keratoconus is a progressive eye condition that affects the cornea, causing it to become thin and cone-shaped. This alteration in the corneal shape can lead to blurred vision and increased light sensitivity.

Symptoms of Keratoconus

• Blurred or distorted vision 
• Increased sensitivity to light
• Glare and halos around lights, especially at night
• Eye strain and headaches
• Frequent changes in glasses or contact lens prescriptions

Treatment of Keratoconus

• Special 'rigid gas permeable contact lenses' for mild cases
• 'Corneal cross-linking' (CXL) procedure, using ultraviolet light and eyedrops
• 'Intacs' surgical inserts placed during a surgical procedure
• Corneal transplant for severe cases

Learn more about the symptoms, diagnosis and treatment of Kerataconus, along with further information, advice and assistive technology suggestions in the article Focus on Kertaconus

Strabismus

Strabismus, is commonly referred to in the UK as a squint and in the USA as 'crossed eyes'. Strabismus is a condition where the eyes do not align correctly. The eyes may turn in towards one another, or they may turn outwards, up or down.

It causes the brain to take in different perceptions which it isn't always able to match to form a picture.  This can lead to double vision, reduced depth perception or blurred vision. The brain may also 'ignore' messages from one eye, which can lead to amblyopia - also known as 'lazy eye'.

Symptoms of Strabismus

• Misalignment of one or both eyes.
• Double vision
• Eye strain and eye tiredness
• Squinting or closing one eye to focus
• Head tilting or head turning
• Poor depth perception

Treatment of Strabismus (Squint)

The treatment of Strabismus - aka squint or crossed eyes - is varied and depends very much on the individual, taking into account the severity and underlying cause of this eye condition.

• Corrective glasses or contact lenses
• Vision therapy which involves eye exercises
• Patches over the 'good eye' to strengthen the misaligned eye
• Surgery to realign the eye muscles

Learn more about the symptoms, diagnosis and treatment of strabismus, along with further information, advice and assistive technology suggestions in the article Focus on Strabismus

Diabetic Retinopathy

Diabetic retinopathy is a complication of diabetes that affects the blood vessels in the retina of the eye. The high blood sugar levels caused by diabetes can damage blood vessels in the retina.  Diabetic Retinopathy can lead to permanent vision loss if not managed effectively.

There are two main types of Diabetic Retinopathy: 'Non-proliferative diabetic retinopathy' (NPDR), and 'Proliferative diabetic retinopathy' (PDR)

Symptoms of Diabetic Retinopathy

• Blurred or distorted vision
• Dark spots or floaters in the field of vision
• Changes to colour vision, colours may fade
• Difficulty seeing well in low light or at night
• Vision loss
  

Treatment of Diabetic Retinopathy

It is important for people with diabetes to have regular eye examinations to detect and treat diabetic retinopathy in its early stages. Treatment of diabetic retinopathy depends on the individual and the type and severity of their diabetic retinopathy. Treatments include:

• Improving blood sugar control
• Laser therapy or injections
• Vitrectomy - a surgical procedure to remove scar tissue from the eye
• Intravitreal injections into the eye

Learn more about the symptoms, diagnosis and treatment of Diabetic Retinopathy, along with further information, advice and assistive technology suggestions in the article Focus on Diabetic Retinopathy

Charles Bonnet Syndrome

Charles Bonnet Syndrome, also known as CBS, is a condition where people who are partially sighted or who are blind experience visual hallucinations. As these hallucinations are visual only, there will be no accompanying sounds or smells etc.

The visual hallucinations may be pleasant but can also be scary, and are sometimes described as 'disturbing'. It is important to recognise that these hallucinations are entirely caused by sight loss and are not a mental health condition. 

The visual hallucinations caused by Charles Bonnet Syndrome happen because the brain tries to 'fill in the gaps' left by a loss of vision-based information.

The hallucinations may only last for seconds, but they may also last longer. Often occurring in a pattern - at the same time each day, or in the same place, for example. They can come on quite suddenly, and also stop after a period of time.

Charles Bonnet Syndrome can be experienced by anyone who experiences sight loss, including AMD, diabetic retinopathy and Stargardt disease. 

Symptoms of Charles Bonnet Syndrome

• Visual hallucinations: these can range from simple patterns to detailed scenes
• Awareness that the hallucinations are not real
• No other sensory factors are involved in the hallucinations

Treatment for Charles Bonnet Syndrome

• Education and reassurance
• Ongoing management of underlying conditions causing vision loss
• Medication or therapy to address any anxiety or stress caused by the hallucinations

Learn more about the symptoms, diagnosis and treatment of Charles Bonnet Syndrome, along with further information, advice and assistive technology suggestions in the article Focus on Charles Bonnet Syndrome or the blog Charles Bonnet Syndrome

Colour Vision Deficiency (CVD)

Colour Vision Deficiency is often referred to as 'Colour Blindness', though this term is becoming outdated. CVD is a genetic condition where individuals have difficulty distinguishing certain colours.

Symptoms of Colour Vision Deficiency

• Difficulty distinguishing between specific colours
• Red - Green colour blindness is the most common CVD
• Inability to see the full spectrum of colours

Treatment of Colour Vision Deficiency

There is no direct treatment for CVD, but colour vision tests can help individuals adapt.

There are colour recognition apps, tinted colour correction glasses and other technology, such as the assistive technology from Dolphin Computer Access which may help with day-to-day things such as reading diagrams or graphs. 

Learn more about the symptoms, diagnosis and treatment of Colour Vision Deficiency, along with further information, advice and assistive technology suggestions in the article Focus on Colour Vision Deficiency

Retinitis Pigmentosa

Retinitis Pigmentosa (RP) is a group of rare genetic disorders that cause a gradual degeneration of the retina - the part of the eye sensitive to light that sends images to the brain - leading to blindness.

Retinitis Pigmentosa usually begins with night blindness, progressing to a gradual loss of peripheral vision, and eventually a loss of central vision.  

Symptoms of Retinitis Pigmentosa

• Night blindness
• Tunnel vision
• Difficulty with peripheral vision
• Loss of central vision
• Difficulty distinguishing colours
• Blurred vision
  
• Eye discomfort or eye pain
• Sensitivity to light - also known as photophobia

Treatment of Retinitis Pigmentosa

• There is currently no cure for Retinitis Pigmentosa.
• Gene therapy and retinal implants are under development.
• Medical doses of certain vitamins can slow down the progress of RP in some cases
• Orientation and mobility training to help people with RP navigate and move around safely
• Low vision aids and assistive technology help ensure people with sight loss caused by RP can still read, study and work on computers.

Learn more about the symptoms, diagnosis and treatment of RP along with further information, advice and assistive technology suggestions in the article Focus on Retinitis Pigmentosa

Amblyopia

A common eye condition in young children, amblyopia is commonly known as 'lazy eye'. Amblyopia is a condition where one eye does not develop normal visual acuity, often due to strabismus or other factors. This means the brain stops using input from this eye to gain information.

Symptoms of Amblyopia

• Reduced vision in one eye
• Poor depth perception
• Squinting or closing one eye
• Difficulty reading and poor performance at school
• Headaches or eye strain after reading
• Abnormal alignment of the eye - also known as Strabismus
• Abnormal movement of the eye - also known as Nystagmus
  

Treatment of Amblyopia

It is important to treat amblyopia in children as soon as possible - preferably before the age of 7 - so that they can develop normal, healthy vision. However, treatment can still be effective in older children and adults

• Patching therapy - where a patch is worn over the 'good eye' to strengthen the brain's connection to the weaker eye
• Atropine drops to blur vision in the 'good eye' which can encourage the brain to use the weaker eye
• Vision therapy to improve eye coordination
  

Learn more about the symptoms, diagnosis and treatment of amblyopia, along with further information, advice and assistive technology suggestions in the article Focus on Amblyopia

Stargardt Disease

Stargardt disease is a rare genetic condition that leads to the degeneration of the macula in childhood or adolescence. Stargardt Disease usually starts bewteen the ages of 6 and 12. There is also a late-onset form of Startgardt Disease that can start at age 50 or over.

Symptoms of Stargardt Disease

• Blurred or distorted central vision
• Difficulty recognising faces or reading
• Colour vision changes
• Difficulty seeing in low light
• A loss of central vision and 'blind spots'
• Sensitivity to bright light
• Visual hallucinations caused by Charles Bonnet Syndrome

Treatment of Stargardt Disease

There is currently no cure for Stargardt Disease, but there are treatments available such as medical administration of certain vitamins and supplements. Other treatments can also help manage the symptoms and slow down the progression of the disease.

Assistive technology devices such as magnifiers, screen readers and special glasses help people with Stargardt Disease live independently and perform activities such as reading, study and work.

Research and clinical trials for new medicines, ongoing development of gene therapy and stem cell therapy for potential treatments are ongoing, with promising results.

Learn more about the symptoms, diagnosis and treatment of Stargardt Disease, along with further information, advice and assistive technology suggestions in the article Focus on Stargardt Disease

Retinopathy of Prematurity

Retinopathy of Prematurity (ROP) is a rare condition that primarily affects very premature babies. When a baby is born before 31 weeks gestation, the blood vessels in their retinas may not develop properly. Most often the cases are mild and may result in a child developing a squint (amblyopia) or wearing glasses due to short-sightedness. In rare cases, the retina can detach, leading to partial or total sight loss. 

Symptoms of Retinopathy of Prematurity

• No obvious or immediate symptoms in infancy
• Routine screening of premature infants is done to detect any signs of ROP
• Paediatric opthalmologist may detect abnormal growth of blood vessels in the retina of premature babies
• Vision problems may manifest in childhood

Learn more about the symptoms, diagnosis and treatment of ROP, along with further information, advice and assistive technology suggestions in the article Focus on Retinopathy of Prematurity

Assistive Technology for Vision Impairments

Living with visual impairments can be challenging, but advancements in technology have made it possible for individuals with sight loss to work, study, and live independently.

Dolphin Computer Access is at the forefront, providing assistive technology products that empower people who are blind or partially sighted. The innovative solutions developed by Dolphin - including screen readers and screen magnification software - builds a bridge to the digital world. Assistive technology allows people with visual impairments to access information, navigate the internet, and use Windows software applications with ease.

Accessibility tools are designed to accommodate a wide range of visual impairments, offering customisable options to suit each individual. Whether you're a student who is blind or partially sighted and who wants to excel in your studies, a professional with a vision impairment aiming to take the next step in your career, or you simply need to find easier ways to do everyday things, without your sight loss holding you back, Dolphin assistive technology will increase your independence. 

Dolphin continues to develop assistive technology that helps anyone with sight loss overcome obstacles and pursue their goals with confidence.