Common vision problems
Short-sighted people will see near objects more clearly than they see far objects. This is because light from distant objects is being focussed in front of the retina. It is unusual to be born short-sighted. Most cases of short sight develop in childhood or teenage years. The first sign may be having to peer at the white board at school or move closer to see things better. Glasses or contact lenses may only be needed for distance vision or they may be required all the time, depending on the degree of short sight. Lenses to correct short sight will be concave, or thicker at the edge.
Long-sighted people will see far objects more clearly than near objects. This is because light from near objects is focussed behind the retina. Often in children and young people the eyes are able to compensate for this by re-focussing so vision may not be blurred. Long sight will often cause symptoms of tired eyes or headaches. In very young children severe long sight can cause one eye to turn, commonly known as a squint. Glasses may be needed to correct a squint or to ease discomfort when reading or performing near vision tasks. In older people, as the eyes' ability to refocus reduces, long-sight can also begin to affect distance vision. Lenses to correct long sight will be convex, or thicker in the centre.
Astigmatism can occur with long or short-sightedness. It occurs because not all eyes are exactly spherical. Some eyes have different degrees of curvature across different meridians. They can be described as more like the surface of a rugby ball than a football. If the difference in curvature is sufficient, this will cause blurring of vision at all distances. Even quite small amounts of astigmatism can cause discomfort with specific tasks such as computer use. Lenses to correct this condition will have different powers across different meridians and will need to sit at the correct angle on your face. Contact lenses to correct astigmatism are often known as toric lenses.
Presbyopia is the reduction in focussing ability which becomes apparent in early middle-age. We are all born with very flexible lenses in our eyes. Tiny babies can easily focus on things a few centimetres away from their faces. As we get older the elasticity of the lenses reduces so that we can no longer ch ange the shape of the lens enough to focus on near objects. For most people this becomes apparent at around the age of 45. You may start to hold things further away to read them, or need more light. You may well experience headaches associated with near vision tasks. As longer arms are not an option, you will need to use glasses or contact lenses to help you see near objects. These may be simple reading glasses or bifocals or varifocals. Contrary to the old wives' tale, wearing glasses will not speed up the rate of deterioration.
Common eye conditions
Cataracts are most common in the over 70 age group, over half of whom will suffer from them. They can also occur in younger people as a result of injury, long-term inflammation, diabetes or certain medication. A cataract is a clouding or discoloration of part of the lens inside the eye. Vision may become hazy or dull, colours appear less bright and bright lights may cause glare problems. Some people notice a double vision similar to looking in a cracked mirror. You may require more frequent ch anges in spectacle prescription. Providing your vision is satisfactory for your needs, treatment may not be necessary. Wearing sunglasses can be beneficial during this stage. When your vision does become adversely affected, your optometrist can refer you to a specialist for an operation. This is usually carried out under local anaesthetic on a day-care basis. Your vision will be improved almost immediately and the insertion of a small plastic lens into your eye may well reduce your need for glasses.
Glaucoma is a range of conditions in which the optic nerve is damaged, usually, but not always, associated with raised pressure inside the eye ball. The most common form is chronic glaucoma, which is painless and symptom-free. It causes a loss of some parts of your visual field. It is almost impossible to notice this in its early stages as central vision is not affected. The rarer acute glaucoma causes sudden, severe pain and requires early treatment. Glaucoma most commonly affects people over 40. It is more common in people with a family history of glaucoma and also in certain ethnic groups, particularly Afro-Caribbean people. Diabetics and very short-sighted people are also more at risk. Early detection of glaucoma is important to prevent loss of vision. Your optometrist will screen everyone over 30 for signs of glaucoma. The eye examination is free for direct relatives of glaucoma sufferers once they are over 40. Additional tests such as retinal photography can be extremely useful in assessing damage to the optic nerve.
Age related macular degeneration
Age related macular regeneration (ARMD) is the leading cause of blindness in people over 50 in the developed world. It is becoming more common as the population ages. It occurs when cells at the macular, which is the area of the retina responsible for seeing detail, become damaged.
There are two basic types of ARMD, usually termed 'wet' and 'dry'. The wet form is more severe but less common. It causes a rapid onset of distorted vision. Early treatment can greatly reduce its impact. Treatment may be by laser or by new drugs which are becoming available.
Dry ARMD may progress very slowly In its early stages it will hardly be noticeable, but reading small print will gradually become more difficult especially in poor light. Stronger glasses will not help with this. There is currently no treatment for dry ARMD.
Those at most risk of developing ARMD are smokers, people with a diet high in fat and low in anti-oxidants and those with a high exposure to sunlight. You can protect yourself by not smoking, improving your diet and wearing good quality sunglasses. ARMD often runs in families. Some people have reduced levels of pigment at their maculae, which increases the risk of developing macular degeneration. Mincher-Lockett Opticians are able to test for this with our Mpod screener and can advise on how you can protect against developing ARMD.
Flashes and Floaters
These are common symptoms which are usually associated with a harmless condition called posterior vitreous detachment. This occurs in late middle-age onwards when the jelly-like substance (the vitreous) in the back of the eye shrinks to the point where it becomes detached from the retina. The vitreous pulling on the retina or bumping into it as you turn your head or eyes can cause the appearance of a flash of light. This symptom will usually reduce after a day or so. You may also see black spots in your vision which will move around. These are bits of debris from the retina which have become loose as the vitreous detaches. They may never disappear completely, but will usually become smaller and settle down within a few weeks or months.
Very occasionally flashes may be a symptom of retinal detachment. For this reason it is important to get your eyes checked as soon as possible by an optometrist if you experience flashes or floaters. The optometrist will usually need to use eye-drops to dilate your pupils to obtain a better view of your retina. You will not be able to drive for several hours after the drops are instilled. In retinal detachment the flashing lights will usually get worse with time and you may be able to detect a dark curtain or shadow across part of your vision. This is due to a hole or tear in the retina which allows fluid to get underneath and separate the retina from the underlying tissue. If caught early it can usually be repaired by laser or freezing.
Flashes can also be a symptom of visual migraine. This causes a disturbance in your vision which can take different forms. Some people describe a jagged circle or zig-zags expanding, others a watery effect. In most cases the symptoms last around 10 to 15 minutes. There is no pain or headache. It is most commonly experienced in middle-age onwards. Most people who experience it will get it only once or twice in their life.
Diabetes is the most common cause of blindness in people of working age. Eye problems usually occur in insulin dependant diabetics and those who have been diabetic for many years. Good control of your diabetes can help to minimise the risk to your sight. Undiagnosed diabetes may also cause frequent ch anges in your vision even at different times of day. If you suspect this, it is important to get your eyes checked as soon as possible.
Diabetic retinopathy occurs because the blood vessels at the back of your eyes are weakened and leak fluid or bleed. If this becomes sight-threatening, treatment may be required with lasers.
Regular eye tests are particularly important for diabetics as you will not be aware if eye problems are starting to develop. Problems in the eyes may also be a indication of problems in other parts of the body.
All diabetics in Staffordshire will be invited to have retinal photographs taken at least once a year to monitor the health of their eyes. The NHS will pay for this and for an eye test to check your vision.
Keratoconus is a rare condition where the central cornea (the clear part of the front of the eye) becomes thinner in the middle. The pressure of the fluid in the eye gradually causes the central cornea to bulge outwards into a cone like shape. In the early stages it will cause an increase in short-sightedness and astigmatism. This usually starts in teenage or early adulthood. Slightly more men than women are affected. The first symptoms will be blurred vision. You may also experience difficulty with bright lights (photophobia). There is no pain associated with the condition. Your optometrist has special equipment to measure the curvature of your cornea if they suspect keratoconus.
In the early stages vision can be corrected with glasses or contact lenses. If the condition progresses, it may not be possible to achieve clear vision with glasses or soft contact lenses. This is because of the irregular shape of the cornea. Better vision may be achieved with rigid contact lenses. The lenses used are specially designed for keratoconus. Eventually, if the cornea becomes too thin, a corneal graft may be required. The rate and extent of progression varies between patients and even between the two eyes of each patient.