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RNIB – supporting people with sight loss
Factsheet
Light sensitivity (photophobia)
Your eyes need light to work. Sometimes people can have
problems with bright light which can happen for a number of
reasons.
How the eye works
Light rays enter the front of your eye through the clear cornea and
lens. It is very important that both the cornea and lens are clear as
this allows the light to pass directly through the front of your eye to
the retina. The cornea and lens bend light so that it can focus on
the retina at the back of your eye. The cornea focuses the light
towards your retina and the lens fine tunes the focussing of this
light. This gives you a clear, precise image.
The tears form a protective layer at the front of your eye and also
help to direct the light coming into your eye.
The iris, the coloured circle at the front of your eye, changes the
size of the pupil which allows different amounts of light into your
eye.
Our pupil is the dark hole in the middle of the coloured part of your
eye. The pupil gets smaller in bright conditions to let less light in
and gets bigger in dark conditions to let more light in.
The middle of your eye is filled with a jelly-like substance called the
vitreous. The vitreous is clear and allows light to pass directly from
the front to the back of your eye.
The retina at the back of your eye is a light-sensitive layer which
consists of rod and cone cells. These cells collect the light signals
and send them as electrical signals to the optic nerve.
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Rod cells are concentrated around the edge of your retina. They
help you to see things that aren’t directly in front of you, giving you
a rough idea of what is around you. They help with our mobility and
getting around by stopping you from bumping into things. They
also enable you to see things in dim light and to see movement.
Cone cells are concentrated in the centre of your retina where the
light is focused by the cornea and lens. This area is called the
macula. Cone cells give you your detailed vision which you use
when reading, watching TV, and looking at people’s faces. They
are also responsible for most of your colour vision.
The optic nerve is made up of thousands of nerve fibres. It’s the
pathway for light signals to travel to your brain. The brain
processes these signals to allow you to “see” the world around us.
Seeing can be likened to the process of taking pictures on a film
with a camera which you then get developed. Your retina is like a
camera film which stores an image of what you are looking at. The
image directed onto your retina is then sent along to your brain
where it is processed, like developing a camera film. Therefore you
actually “see” in your brain with the light information sent to it from
your eyes. This whole process happens very quickly so that
everything you see is in focus.
Why is light important to vision?
We need light to see what is around us and its colour. Light
bounces off the objects we look at and different objects will reflect
different amounts of light.
Light entering our eyes is collected by our retina and processed by
our brain to obtain the pictures that we need to see. Light is an
essential part of this process, for example it is difficult to read when
light levels are low. Sometimes light can cause problems for our
vision.
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What are the problems with light that can
occur?
There are times when the amount of light or the quality of that light
can affect our ability to see. Many people with low vision need
more light than usual to read. However, too much light can cause
problems with glare.
What is glare?
Glare is when a light source affects our ability to see clearly. There
are two types of glare; discomfort glare and disability glare.
What is discomfort glare?
Discomfort glare occurs when a light source is just too strong for
our eyes. It may cause us to screw up or shade our eyes; it can
even cause us to close our eyes.
A good example of when we might experience discomfort glare is
when we leave a dark room and move into bright sunlight. As our
eyes adjust the light feels uncomfortable and sometimes painful.
Usually our eyes adjust to the new level of light and we are able to
see clearly again after a few seconds. Our eyes adjust to the new
level of light by making our pupil smaller (constricting). As the
name suggests, discomfort glare can make our eyes feel
uncomfortable.
What is disability glare?
Disability glare reduces how well we can see. Disability glare can
be caused by eye conditions and can occur with ordinary light
sources and levels of light.
The structures of our eyes are normally clear which means light
can pass smoothly through our eye. As we age certain eye
conditions can make our eye’s structures less clear. The most
common example of this is a cataract.
If you have a cataract, the lens in your eye is not as clear as it
should be. This causes the light entering your eye to scatter as the
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light is unable to pass smoothly through your lens. This effect, as
well as making things unclear and blurred, also makes coping with
bright light difficult. The amount of light scatter depends on the
amount of light entering your eye and how advanced your cataract
is. A brighter light will scatter more and cause more glare. People
with cataracts often have a lot of trouble with glare.
What are the causes of glare?
Some eye conditions can cause glare, including:
 Ocular albinism – this is when some people are born with a lack
of pigment in the eye
 Cataracts
 Macular degeneration
 Uveitis
 Conditions which affect the front surface of the eye such as
conjunctivitis, dry eye or corneal problems.
There are also some other conditions such as meningitis which
cause light to be very painful quite quickly.
Some drugs taken for other conditions can also cause light
sensitivity. Examples can include tetracycline, an antibiotic, and
digitalis, a drug used for heart problems.
If you start to experience light sensitivity, it’s important to see an
optometrist to have your eyes checked. An optometrist will be able
to examine the health of your eyes to check for any underlying eye
condition which may need treatment.
If your light sensitivity comes on very suddenly then it should be
checked as soon as possible in case it is the first sign of a more
serious condition such as meningitis.
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What can be done about light sensitivity?
Treatment for light sensitivity depends on the cause. Usually if the
light sensitivity is a symptom of an underlying eye problem such as
cataract, then treatment for your cataract can solve the glare
problem. Treating eye conditions, like uveitis, often means that
your eye becomes less light sensitive.
Unfortunately not all light sensitivity caused by eye problems can
be treated, for example, the light sensitivity caused by macular
degeneration. If this is the case then you may have to use other
ways to help you cope with bright light.
What other ways are there for coping with light
sensitivity?
The most obvious way to cope with glare is to limit the amount of
light that’s entering your eye. Shading your eyes with your hand or
wearing a hat with a wide brim can help cut down on glare with
little expense.
Tinted lenses help to minimise the light entering your eyes and so
cut down on the amount of glare you experience.
Sunglasses should have an UV filter so they also protect your eyes
from the harmful UV rays of the sun. The best lens will have
protection against both UVA and UVB light.
Some people prefer to have light activated sunglasses, which get
darker in brighter conditions, though this is a personal choice.
Polarized lenses can cut down on reflected glare from flat
surfaces, for example light reflected off water or snow or off the
bonnet of a car.
There are sunglasses, sometimes called solar or UV shields or
wrap-around shades, which are larger than normal. They have built
in sides which stop the light entering that way and they are also
made to stop the light entering from above your eyes. They can
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also be worn over your normal spectacles and come in a variety of
tints. These can be very helpful but the fit of them is important.
Everyone has a different shaped head and it’s useful to try on
several pairs of wrap-around sunglasses to find the ones which fit
closest and stop the most light from coming in around the edge of
the frame.
A low vision specialist can give you advice on coping with glare.
They can talk to you about the best way to use lighting to avoid
glare. This is especially important since it can be difficult to
balance the amount of light someone with a sight problem needs
for tasks such as reading and the fact that they may have a
problem with glare.
Some eye conditions can make moving between areas with
different lighting levels difficult. For example, when moving from
sunlight into a dim room, or vice versa. It may be necessary to
pause and put sunglasses on or take them off and give your eyes
time to adjust. It’s important that you don’t feel rushed and to give
yourself time. Often, these changes in light levels occur at the
entrance to buildings, which can be particularly dangerous as there
are often steps in these places.
Many people with a sight problem find that using a task light for
activities such as reading helpful. The best lights for this type of
task are adjustable lamps so that you can direct the light to where
you need it the most. The best position for an adjustable lamp
when you need more light for a task is between you and what you
want to look at, directed at the task, below your eye level. This can
reduce the amount of glare.
There is much more information on lighting and low vision in our
Starting out – Making the most of your sight leaflet.
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I don’t have an eye condition so why am I still
very light sensitive?
Some people have light sensitivity even though they don’t have an
eye condition. It’s still important, if you begin to experience light
sensitivity, to have your eyes checked by an optometrist (optician)
as there may be an eye condition that hasn’t yet been picked up.
Unfortunately some people are sensitive to light without there
being a physical cause.
It’s important to remember that there is a range of light sensitivity.
Some people are just more sensitive to light than others. Also as
we grow older we can also become more sensitive to light; this is
because our eye changes even though there is no underlying eye
condition.
Even though there may be no physical cause for your light
sensitivity it can sometimes be very intense. The advice about
sunglasses and hats can often help anyone with light sensitivity.
Wearing correct sunglasses will not harm your eyes or make them
lazy.
Using the least amount of tinted lenses while you are inside is best
because the darker things are, the more the light will bother you. It
is important to get advice from your optician on what tints or level
of tint to wear during the day when driving to make sure your
lenses allow enough light in for safety and meet any DVLA
regulations. The Highway Code warns against using any form of
tint for night driving. You may want to talk with your optometrist
about using clear lenses with an anti-reflection coating. Some
people find that they can help to reduce glare when driving at
night. Your optician will be able to explore this further with you.
People who suffer from migraine tend to be more sensitive to light,
to a marked degree during a migraine headache and also to a
lesser degree at other times. Sometimes, certain types of light or
patterns can trigger migraine. Some people with migraine may
therefore benefit from special tinted lenses, called precision tinted
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lenses. These can also help people who experience glare from
pages of text, including some people who have dyslexia. Precision
tinted lenses are discussed below.
Are there special tints that work for different
sight problems?
Coloured lenses with particular tints limit certain wavelengths of
light and are often used to help people with light sensitivity. The
colours of these tints range from yellow to reds to blues. At the
moment there is no strong evidence that a particular shade of tint
suits one eye condition over another and it would appear that
choosing the tint is a matter of personal choice. For example two
people with macular degeneration may prefer two completely
different coloured tints. However, people with conditions where
light is scattered in the eye (for example, cataract) often find filters
that block out short wavelengths, such as yellow or amber filters,
helpful.
Most optometrists and low vision providers will be happy to discuss
the different tints available with you; they can sometimes also lend
you a type of tint to test over a period of time. This may help you
find the best tint for helping with your light sensitivity.
A special instrument, the MRC Intuitive Colorimeter, is sometimes
used to determine the colour of filter that will be most helpful for a
given person. This instrument is not often used for people with low
vision, but is commonly used to prescribe coloured lenses for
people with migraine, reading problems (eg dyslexia), or epilepsy.
This is because people with these conditions often find a precise
colour, which is different for each person, to be much better than
general colours and help with any visual symptoms.
What support services are there?
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London
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Last updated: June 2015
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