A guide to your eyes
Refractive Error
Also known as refraction error, is a problem with focusing light accurately on the retina due to the shape of the eye and or cornea. The most common types of refractive error are near-sightedness, far-sightedness, astigmatism, and presbyopia. Near-sightedness results in far away objects being blurry, far-sightedness and presbyopia result in close objects being blurry, and astigmatism causes objects to appear stretched out or blurry. Other symptoms may include double vision, headaches, and eye strain.
Near-sightedness is due to the length of the eyeball being too long, far-sightedness the eyeball too short, astigmatism the cornea being the wrong shape, and presbyopia aging of the lens of the eye such that it cannot change shape sufficiently Some refractive errors occur more often among those whose parents are affected.Diagnosis is by eye examination.
Refractive errors are corrected with eyeglasses, contact lenses, or surgery. Eyeglasses are the easiest and safest method of correction.Contact lenses can provide a wider field of vision; however they are associated with a risk of infection Refractive surgery permanently changes the shape of the cornea.
The number of people globally with refractive errors has been estimated at one to two billionRates vary between regions of the world with about 25% of Europeans and 80% of Asians affected. Near-sightedness is the most common disorder. Rates among adults are between 15-49% while rates among children are between 1.2-42%. Far-sightedness more commonly affects young children and the elderly. Presbyopia affects most people over the age of 35.
The number of people with refractive errors that have not been corrected was estimated at 660 million (10 per 100 people) in 2013 Of these 9.5 million were blind due to the refractive error It is one of the most common causes of vision loss along with cataracts, macular degeneration, and vitamin A deficiency
Age-Related Macular Degeneration
AMD is a condition that affects the central part of your vision. It is caused by damage to the macular region of the eye, which is the part of the retina that provides detailed, central vision. It doesn’t normally affect your peripheral (side) vision, so while objects in the centre of your vision may become difficult to see, the vision to the side and edges should not be affected.
There are two main types of AMD
WET AMD happens when new blood vessels grow behind the macula. These blood vessels can begin to leak and this can damage the cells in the macular region and stop them from working. Wet AMD will normally cause distorted vision, with straight lines and edges such as door frames becoming wavy and distorted. Some people also see a sudden blank spot in their central vision. This process can start very suddenly so it’s important to see your optometrist urgently if you notice any sudden change in your vision..
DRY AMD sometimes referred to as wear and tear, is caused by a build-up of waste within the cells of the eye that react to light – these are called drusen. Drusen stop the cells from reacting properly to light. This form of AMD usually develops slowly and may initially have little effect on your vision. If the disease develops, your central vision may gradually become more blurred and it may become difficult to recognise faces and read things directly in front of you. Sometimes these changes can happen quickly, so it’s important to see your optometrist urgently if you notice any changes in your vision.
Cataract
A cataract is a clouding of the normally clear lens of the eye. For people who have cataracts, seeing through cloudy lenses is a bit like looking through a frosty or fogged-up window. Clouded vision caused by cataracts can make it more difficult to read, drive a car (especially at night) or see the expression on a friend's face.
Most cataracts develop slowly and don't disturb your eyesight early on. But with time, cataracts will eventually interfere with your vision.
At first, stronger lighting and eyeglasses can help you deal with cataracts. But if impaired vision interferes with your usual activities, you might need cataract surgery. Fortunately, cataract surgery is generally a safe, effective procedure.It is important to have regular eye checks, so that signs of cataract or progession of the cataract, can be monitored. We can also refer you directly, either privately or via the NHS, when the cataract becomes a problem for your vision.
Diabetic Retinopathy
Diabetic retinopathy is a complication of diabetes, caused by high blood sugar levels damaging the back of the eye (retina). It can cause blindness if left undiagnosed and untreated. However, it usually takes several years for diabetic retinopathy to reach a stage where it could threaten your sight.
To minimise the risk of this happening, people with diabetes should:
- ensure they control their blood sugar levels, blood pressure and cholesterol
- attend diabetic eye screening appointments – annual screening is offered to all people with diabetes aged 12 and over to pick up and treat any problems early on
Glaucoma
Glaucoma is the name given to a group of eye conditions where the optic nerve at the back of the eye is damaged. It is often linked with raised pressure within the eye, although the eye pressure can sometimes be normal. When the nerve is damaged, it can start to cause problems with the peripheral vision (side vision) and, if left untreated, can cause permanent damage. With early treatment, further damage to vision can be prevented. The condition often happens in both eyes, although sometimes it affects one eye more than the other. Glaucoma is one of the leading causes of severe sight impairment.
There are two main types of glaucoma – open-angle (chronic) glaucoma and closed-angle (acute) glaucoma. Even though there are many different causes of the disease, the outcomes are very similar. Glaucoma may not have symptoms and this is why it is very important to have regular sight tests.
Amblyopia
It's known medically as amblyopia. It happens because one or both eyes are unable to build a strong link to the brain. It usually only affects one eye, and means that the child can see less clearly out of the affected eye and relies more on the "good" eye. It's estimated that 1 in 50 children develop a lazy eye
Strabismus
A squint, also called strabismus, is where the eyes point in different directions. It's particularly common in young children, but can occur at any age. One of the eyes may turn in, out, up or down while the other eye looks ahead. Credit: This may happen all the time or it may come and go
Stye
A stye is a small abcess (painful collection of pus) on the eyelid and is an infection at the root of an eyelash. It appears as a small painful red lump, often with a yellow spot in the middle, on the outside of the eyelid.
Other symptoms include a watery eye and a red eye or eyelid. It's not always necessary to see a doctor if you develop a stye, although if you have a painful and very swollen eyelid with a stye, you should have it checked.
Most styes get better without treatment within a few days or weeks. Styes may burst and release pus after three or four days. A warm compress (a cloth warmed with warm water) held against the eye encourages the stye to release pus and heal more quickly.
Further treatment is not usually needed unless you have a very painful stye that is not getting better or a very swollen red lid indicating spreading infection. In this case, see your doctor who may decide to treat it with antibiotics, drain it or refer you to an ophthalmologist.
You should never attempt to burst a stye yourself.
Blepharitis
Blepharitis is a common eye condition that causes the eyelids to become sore and inflamed
What is blepharitis?
Blepharitis causes eyelids to become red, swollen and inflamed. It doesn’t normally cause serious damage to the eyes, but it can be very uncomfortable. It tends to be a long-term condition, which means you’re likely to need ongoing treatment. Severe cases do have a risk of causing long-term damage, but fortunately these are quite rare.
Types of blepharitis
There are two main types of blepharitis – anterior and posterior.
Anterior blepharitis
When the front (anterior) part of the eyelids becomes sore, this can be caused by an infection, allergy or a general sensitivity to bacteria present on the eyelids. It can also be associated with some scalp conditions, such as very dry or oily skin and dandruff.
Posterior blepharitis
Also known as meibomian gland dysfunction (MGD) is when the glands that make the oily part of your tears become blocked. Both types of blepharitis can cause dry eye or make it worse if you already have it. Many people will have a combination of blepharitis, meibomian gland dysfunction and dry eye.
Risk factors
Blepharitis is more common in people over the age of 50, but anyone can develop it. This is often because the glands that make the normal tears, particularly the oily part of the tears, tend to become less effective as you get older.
Symptoms
Blepharitis can cause crusting and white scales may stick to the roots of eyelashes. Your eyelid edges may become red and your eyes will feel gritty, burning, sore or itchy. If you experience these symptoms, make an appointment with your optometrist.
Treatment
There is a range of products designed especially for treating blepharitis, such as sterile pads, individual moist wipes and separate cleaning solutions.
Your optometrist will be able to advise you on where you can buy these products. Antibiotic ointment may be recommended in severe cases.
As part of the treatment, you need to remove all the crusting and debris from the edge of your eyelids and from between your eyelashes. You should use your cleaning product. If this is not available, you should use warm water and cotton balls or make-up removal pads. Treatment of blepharitis is a long-term procedure. You may not see any improvement for several weeks.
Continue the treatment twice a day for at least one month, then less often as it starts to get better. You will probably need to continue to clean your lids at least twice a week to help prevent the blepharitis from returning.
Blepharitis treatment method
Wash your hands before and after cleaning your eyelids
Rub the moistened pad or cotton ball firmly but gently along the eyelid edges to remove the crusts and debris
Take care to wipe between the eyelashes of both the upper and lower lids
Use a fresh pad or wipe each time
Dry your eyes gently