Healthy eyesight

Expert reviewer, Professor Simon Taylor, Consultant Ophthalmic Surgeon
Next review due, March 2021

Your eyesight can change as you go through life. A noticeable example is that you may start to need glasses for reading. Some changes to your vision are normal, but they can still be worrying.

Your eyes are affected by your lifestyle and general health, in the same way as the rest of your body. So it’s important to know how to look after your eyes and spot any problems as soon as they crop up.

A close-up photo of a woman's eye

How do you know if your eyesight is 'normal'?

Most adults have healthy eyes with normal vision until their 40s. To an eye specialist, ‘normal’ means that you can read to the end of the sixth line on their eye chart, from six metres away. In the UK we call this 6/6 vision. In the United States, the same thing is called 20/20 vision, which has become a term people use for normal sight.

To have normal vision, you should have no problems focusing at a distance, reading close up or on the computer. But the only way you can really tell is to have an eye test. Everyone should have an eye test at least every two years. Your optician will check your eye health and general health as well as your vision.

There are other aspects to your sight, apart from focusing. Your vision should not look clouded or patchy, which are both symptoms of eye conditions. Healthy eyes should be clear and bright, with no redness or soreness. As you get older, it may be normal to sometimes see ‘floaters’ – shapes that look as though they’re floating in your eyes. But if you suddenly see a lot more shapes with bright, flashing lights, this can be an early sign of a tear in your retina (the light-sensitive lining of your eye). Loss of side vision can be a sign of an eye disease called glaucoma.

Your eyes are precious. If you have any concerns at all, go and see your optician or GP.

Common eyesight problems


As you get older, particularly past the age of 40, you may notice that you are holding reading matter further away so that you can focus on it properly. This is age-related long sight. Doctors call it presbyopia. Most of us will need reading glasses eventually. Some people prefer multifocal contact lenses, which enable you to focus close up and see at a distance. You can now have laser surgery for age-related long sight.

Long-sightedness that is not age-related is called hyperopia. Many people have some degree of long-sightedness. It isn’t a problem unless you feel you can’t see well enough close up, or it causes eye strain or headaches.

We have more information about long-sightedness.


If you have trouble seeing things in the distance, you may be short-sighted. Short-sightedness, or myopia, usually develops before the age of 20. You can sometimes develop symptoms of short-sightedness if you have focused on something very close up for a long time. Your eyes find it difficult to adjust to focusing further away. This usually gets better after you’ve rested your eyes. But if you do a lot of close work, it can become permanent.

We have more information about short-sightedness.

Other problems with sight

Diabetic eye disease

Diabetes causes blood sugar levels that are too high. This can damage the blood vessels in the light-sensitive lining at the back of the eye (the retina). If the diabetes isn’t treated, this can lead to blindness. Many people are now developing type 2 diabetes later in life. An optician may be able to see signs of diabetes during an eye test, even if you don’t know you have it.


Glaucoma is one of the commonest eye conditions in people aged over 40. A build-up of pressure inside the eye can damage the optic nerve, causing sight loss and even blindness if not treated. It is more common in women and tends to run in families. If a close member of your family has glaucoma, you may need to have eye tests more often. If you are over 40, these will be free. The optometrist will examine the optic nerve at the back of your eye. They will also measure the pressure inside your eye, by using a small puff of air. It is important to have these tests because early glaucoma may not have any symptoms. 


If you have cataracts, it means the lens inside your eye is becoming clouded. This usually happens slowly, as you get older. The only treatment is surgery to remove the affected lens and replace it with an artificial one. You can have this done as soon as the cataract is affecting your sight – you don’t have to wait until it becomes ‘ripe’.

Find out more about cataracts and cataract surgery.

Age-related macular degeneration

Age-related macular degeneration (AMD) affects an area in your retina called the macula. This is where your vision is at its sharpest. Macular degeneration means that the macula has become damaged. This can make your vision patchy and straight lines may look wavy. You may have difficulty recognising faces or watching TV. Your vision to the sides (peripheral vision) isn’t usually affected.

You can check your sight for signs of AMD. Look at a straight line, such as a door frame with each eye in turn. If there are any patches or the door frame doesn’t look straight, see your optician or eye specialist.

Retinal detachment

The retina is the light-sensitive lining of your eye. If this tears or comes away from the back of the eye (retinal detachment), you’ll need to visit accident and emergency (A&E) at your local hospital for treatment. Some local hospitals have dedicated eye casualty units that you can go to instead.

Signs of a tear or detachment include seeing large, black shapes floating across your vision, seeing bright flashes in front of your eyes or a shadow spreading across the vision of one eye. Seeing small floating particles in your eyes is quite normal. But if there are suddenly many more of these or they are much larger than normal, visit A&E or eye casualty.

See our page on retinal detachment for more information.

Who is at risk of eyesight problems?

Many eye conditions become more common as we get older. The commonest is age-related long sight, or presbyopia. It’s commonest because it affects just about everyone over 40 to some extent.

Cataracts, macular degeneration and glaucoma all become more common with age. Around seven out of 10 people (70%) in their 80s have cataracts, but it is around one in two people (50%) in their 60s. About one in six people (12%) over 80 have age-related macular degeneration (AMD), but only around one in 20 people (5%) in their 60s.

Glaucoma is more common in older people, but that is because it takes a long time to develop. If untreated, it can take more than 25 years to affect your sight.

Your ethnic background can also affect your risk. Glaucoma is more common in people of African-Caribbean descent. AMD is most common in white (Caucasian) people. Glaucoma and cataracts are also more common in women than men.

Causes of eyesight problems

We don’t always know why one person develops a medical disorder and others don’t. But, apart from age, there are some known causes for the commonest eye conditions.

The cause of short and long sight is the shape of your eyeball. If your eyeball is longer or shorter than normal from front to back, it affects the point where light from objects becomes focused on the back of the eyeball. Of course, you can’t do anything about that – it’s something you’re born with. Not surprisingly, short and long sight tend to run in families. If you are short-sighted, you are also more at risk of glaucoma.

Having other medical conditions can affect your risk of some eye diseases. Eye damage is a complication of diabetes and having diabetes can also increase your risk of glaucoma and cataracts. Glaucoma is also linked to high blood pressure and macular degeneration to cardiovascular disease.

Your lifestyle can affect your likelihood of developing some eye conditions. Macular degeneration (AMD) and cataracts are both associated with diets low in fresh fruit and vegetables. Smoking can have a big effect – it increases your chances of having cataracts and AMD. Smoking can also make AMD worse.

Having an eye test

It’s best to have regular eye tests, but you should certainly have one if:

  • you can’t see as clearly as you used to
  • you have any problems reading, such as with small print
  • objects at a distance aren’t as clear, for example you can’t see the TV clearly

If you have any sudden changes in your sight, you should go to the accident and emergency department.

Your optician will ask you some questions about your general health. Then they will:

  • ask you to read letters from an eye chart a fixed distance away
  • look inside your eyes with a bright light, using an ophthalmoscope
  • ask you to look from side to side and up and down, to check your eye muscles
  • check the pressure inside your eye with a puff of air – this may make you jump but it doesn’t hurt

If you wear (or need) glasses or contact lenses, your optician will ask you to read the eye chart while you have different lenses placed in front of your eyes. This is to check the prescription that you need for your lenses.

Eye tests usually cost between £20 and £40. Your optician may suggest extra tests, such as photographing the inside of your eye and there may be extra charges for those. Some people do not have to pay, including children, the over 60s and people with diabetes or glaucoma in the family. You also don’t have to pay if you live in Scotland.

Glasses and contact lenses

If you need glasses or contact lenses for short or long sight, there are plenty of choices to make. The most important thing is that you have the right prescription from your optician. If you wear the wrong glasses or lenses, you may have headaches or eye strain.

Some people are more comfortable with glasses and others prefer contact lenses, so it may be a case of trial and error. Here are some things to think about.

  • If you only need glasses for reading and both eyes need the same strength lens, you can use off-the-shelf reading glasses, which are much less expensive – but you still need regular eye tests.
  • Contact lenses tend to work out more expensive. As they need replacing regularly, there can be lens care costs, and you will still need to have a pair of glasses.
  • If you depend on your lenses, you will need glasses as well for when you’re not wearing them.
  • Contact lenses give you unrestricted vision and may be better for sports.
  • If you have dry eyes, tend to get eye infections or have allergies, contact lenses may not suit you.
  • You need to be comfortable touching your eyes to use contact lenses – most people are able to learn how to put them in and take them out.
  • You have to be committed to looking after the lenses properly, particularly keeping them clean.
  • Not cleaning lenses properly increases your risk of an eye infection.
  • If you wear lenses every day, you may prefer daily disposables, but they do cost more.

Laser eye surgery

This is also known as laser refractive eye surgery. You can have this treatment to correct your sight if you have long or short sight. The surgeon uses a laser to alter the shape of the covering of the eye (the cornea). This focuses light in the right place on your retina.

You can now also have laser eye surgery if you have age-related long sight. The surgeon treats one eye for distance and the other for close vision.

See our information on laser eye surgery for more information.

Frequently asked questions

  • Your general health and lifestyle will affect your eyes. There is evidence that diet is a factor in some eye conditions, such as cataracts. As ever, eating more fresh fruit and vegetables may be protective. Oily fish may also be good for eye health.

    Again, no surprise but smoking can be bad for your eyes. If you smoke, you have an increased risk of macular degeneration and cataracts.

    It’s important to protect your eyes from the sun. Choose sunglasses that cut out 99 or 100% of both UVA and UVB. Good quality sunglasses will have this on the label. You should also never keep looking directly at the sun, which can cause serious damage to your vision.

    Aside from staring at the sun, it’s generally a myth that using your eyes can damage them. Using a computer, watching TV or lots of reading won’t harm them. But if you do a lot of close-up work or are on the computer for long periods, it’s a good idea to rest your eyes regularly. The 20-20-20 exercise can help to reduce eye strain: look 20 feet away for 20 seconds, every 20 minutes.

  • Most children have good vision and don’t need glasses. But they should have an eye test when they start school, or earlier if you are at all concerned. They don’t need to be able to read as your optician can use pictures or symbols. Your child may be more likely to develop eye problems if:

    • they were born prematurely
    • they have special needs
    • squint or lazy eye runs in the family
    • others in the family wore glasses at a young age

    Squint means that one eye is turning inwards or outwards more than the other. It tends to happen in children who are very long-sighted. If not treated, your child could develop a lazy eye, which means it isn’t working properly. Your child will need glasses to correct the squint.

    Other signs that your child is having difficulty seeing include:

    • rubbing their eyes or having watery eyes
    • seeming clumsy and have trouble with hand–eye coordination
    • avoiding reading or writing
    • sitting very close to the TV or holding books very close to their face
    • screwing up their eyes when reading or watching television
    • not doing as well at school as they should

    If you have any worries about your child's vision, see your optician or GP.

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  • Reviewed by Graham Pembrey, Lead Editor, Bupa Health Content Team, March 2018
    Expert reviewer, Professor Simon Taylor, Consultant Ophthalmic Surgeon
    Next review due, March 2021