There are a wide range of eye conditions that can cause sight loss. Below are some of the most common eye conditions, their symptoms, treatment options and where to find more information. If you’re concerned about your eye health, book an appointment with your local optometrist (optician), GP or eye clinic.
What is the definition of low vision?
Low vision is an impairment of visual function that causes restriction in everyday life, but cannot be corrected by conventional spectacles, contact lenses or medical intervention. It includes, but is not limited to, people who are registered as blind or partially sighted.
Key Symptoms of low vision include:
- Difficulty reading
- Problems differentiating between colours
- Difficulty seeing far-off objects, such as street signs
Low vision can be caused by a variety of factors – it mainly affects older people, though is not a natural symptom of ageing. Eye diseases are also a main contributing cause, such as glaucoma, diabetic retinopathy and macular degeneration.
Diagnosing low vision early makes treatment more effective and allows for maximum independence to be maintained – a low vision eye examination from your optometrist will determine whether you have the condition.
What is Retinitis Pigmentosa?
Retinitis Pigmentosa (RP) is the name given to a group of genetic conditions that affect the retina’s ability to respond to light. These conditions cause a slow loss of vision, beginning with night vision and peripheral (side) vision and eventually affecting central, colour and reading vision.
RP has three main inheritance patterns: autosomal recessive, autosomal dominant and X-linked inheritance, depending on the genetic cause. RP affects approximately 1 in 3,000 to 4,000 people in the UK.
The symptoms of RP vary depending on the type, but most people will first notice visual problems at dusk or in poor light and a gradual reduction in the peripheral field of vision. At an early stage, the central (straight ahead vision) is unaffected, but as the outer edges of the field of vision gradually disappear, the RP sufferer can be left with ‘tunnel vision’. The loss of central vision is slower than peripheral vision. The age at which symptoms start is variable and the rate of deterioration often varies but is generally very slow with changes occurring over years rather than months.
There is currently no cure for RP, however there is a huge amount of work being done on developing treatment options in the area of genetic retinal conditions, and researchers are reporting promising progress.
What is glaucoma?
Glaucoma is the name given to a group of eye conditions that cause sight loss by damaging your optic nerve. Sight loss caused by glaucoma is permanent but there are methods of prevention.
Glaucoma damage may be caused by increased eye pressure or a weakness in the optic nerve. In most cases both eye pressure and weakness in the optic nerve are involved to some extent.
Symptoms associated with glaucoma include hazy or blurred vision, severe eye or head pain, nausea and vomiting, sudden sight loss, and the appearance of rainbow-coloured circles around bright lights.
As there is no way to repair glaucoma damage, treatments are designed to reduce further loss of sight. The main course of action is to decrease pressure in the eye. Typically this is done using eye drops, however if that is not shown to work quickly enough laser treatment or an operation may be necessary.
Age-related macular degeneration
What is age-related macular degeneration?
Age-related macular degeneration (AMD) is an eye condition affecting a small part of the retina called the macular. AMD is categorised as either ‘wet’ or ‘dry’. Dry AMD causes graduation deterioration of the macular, usually over many years, as the retinal cells die off and are not regenerated. Wet AMD occurs when abnormal blood vessels grow into the macula and leak blood or fluid, which leads to scarring and rapid loss of vision. The condition will affect central vision, but is not painful and will not lead to total sight loss.
The exact cause of the condition is unknown, but factors such as age, gender, genes and a number of lifestyle choices are thought to increase your chances of developing AMD. It is the most common cause of sight loss in the developed world. In the UK over 600,000 people are affected.
Symptoms of AMD vary, but typically the inability to see details clearly is the first indicator. Straight lines such as door frames and lampposts may appear distorted, and objects may change shape, size or colour. A blurred area or dark spots in your sight can also suggest AMD.
Wet AMD can be treated with Anti-VEGF treatment if caught quickly. This is a course of drugs, injected into the eye under local anaesthetic, which stops your body creating new blood vessels. At this stage, there is no treatment for dry AMD.
What are cataracts?
Cataracts are a common eye condition in which the lens inside the eye gradually becomes less transparent with age. Over time, a cataract can become worse, making vision cloudier, but it is usually treatable with a straightforward operation.
There are a number of causes for cataracts, but age is by far the most common. Other recognised triggers can include diabetes, trauma, medications such as steroids, and eye surgeries for other conditions.
Cataracts tend to develop in both eyes, leading to deterioration in vision quality, and specifically a loss of focus. Difficulty with bright lights is also a common symptom, as are changes in colour vision.
The only effective treatment for cataracts is surgery. The cloudy lens in the eye is removed and replaced with an artificial implant.
What is diabetic retinopathy?
Diabetic retinopathy is a complication of diabetes that damages the tiny blood vessels that deliver blood to the retinas. The condition can cause blindness if left undiagnosed and untreated.
Diabetic retinopathy is caused by a high blood sugar level that, over time, damages the delicate blood vessels surrounding the retinas.
Symptoms of diabetic retinopathy include slowly deteriorating vision, sudden sight loss, floating shapes in your field of vision, blurred or patchy vision, as well as eye pain and redness.
Treatment for diabetic retinopathy is only necessary if there is an immediate threat to your vision. Unless the condition has reached a stage where sight loss is a risk, lifestyle changes recommended for those with diabetes can be effective in reversing the damage. However, more advanced cases of diabetic retinopathy can require laser treatment, injections or an operation to remove blood or scar tissue from the eye.
What is Keratoconus?
Keratoconus is a progressive eye condition where the normally dome-shaped cornea thins and begins to bulge into a cone-like shape. This distortion deflects light as it enters the eye on the way to the retina, which causes distorted vision.
In most cases, the exact cause of Keratoconus is unknown, but researchers have found a familial link so genetics are thought to be a factor. It is also more common in people with allergic diseases such as asthma, in Down’s syndrome, and in some disorders of connective tissue such as Marfan’s disease.
Early signs of keratoconus are usually blurred vision and frequent changes in lens prescription, or poor vision that cannot be corrected with glasses. Other symptoms include light sensitivity, a halo around lights (particularly at night), eye strain and headaches. Symptoms usually begin in late teenage years to early twenties, but can start at any time.
Keratoconus can be treated with glasses or contact lenses designed to correct the distorted vision caused by the bulging of the cornea. Advanced cases of keratoconus can require Corneal Transplant Surgery.
Birdshot chorioretinopathy (also known as Birdshot Uveitis)
What is birdshot chorioretinopathy?
Birdshot chorioretinopathy is a rare, progressive inflammation of the iris, choroid and cilary body, which together make up a part of the eye known as the uvea. If left undiagnosed or untreated, the condition can cause blindness.
The exact cause of birdshot chorioretinopathy is not known, however it is believed to be an autoimmune disease. The majority of people diagnosed with birdshot carry an antigen called HLA- A29, which could mean they have an inherited immune dysregulation, however many people who carry the antigen never contract birdshot so researchers have yet to prove this theory.
The most common initial signs of birdshot are floaters and blurred vision caused by inflammatory cells in the jelly-like substance between the front and back of the eye. This is generally followed by gradual, painless loss of vision in one or both eyes.
There is no one definitive treatment for Birdshot, but high dose steroids are nearly always used initially to quell inflammation as quickly as possible. Because of the effects of long-term steroid use on the eye, patients who require ongoing treatment are likely to be switched to an immunosuppressant as soon as the inflammation is under control.