Ocular hypertension - Moorfields Eye Hospital

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International Glaucoma Association Woodcote House,
15 Highpoint Business Village Henwood, Ashford, Kent
TN24 8DH
Telephone: 01233 64 81 64
Email: [email protected] • www.glaucoma-association.com
OCULAR HYPERTENSION
A GUIDE
Charity registered in England and Wales No. 274681 and Scotland No. SC041550
© International Glaucoma Association 2011
The International Glaucoma Association is registered under
the Data Protection Act 1998 of the United Kingdom.
Your information will be held on a database within the UK.
The database will be administered and controlled by the
International Glaucoma Association, Woodcote House 15
Highpoint Business Village Henwood, Ashford TN24 8DH.
By completing this request form you agree that we may
use the information you have given in the following way:
• To maintain records of donations and requests for
information.
• To use for future requests for support.
Only the IGA will have access to your information. It will
not be disclosed to other third parties except to the extent
required by the laws of the United Kingdom.
Supported by Pfizer Ltd
Printed June 2011
Review date June 2014
This free booklet is brought to you by the
International Glaucoma Association (IGA). It has been
funded by the voluntary donations of our members and
friends, as well as a grant from Pfizer towards printing
costs. Pfizer was not involved in the development of the
content of this publication.
Don't forget:
- take your eye drops as prescribed by your consultant
as it is the only way to avoid further sight loss in most
cases
- tell your close relatives that you have ocular
hypertension and that they are at higher risk so that
they can be tested too as early as possible
Contact the IGA for further information or advice:
International Glaucoma Association
Woodcote House, 15 Highpoint Business Village
Henwood, Ashford, Kent TN24 8DH
- contact the IGA Sightline if you have any questions,
we are here to help you
Telephone:
01233 64 81 64
Sightline:
01233 64 81 70
(Monday-Friday 9.30am-5.00pm)
01233 64 81 64
[email protected]
www.glaucoma-association.com
A membership form is enclosed in the middle of this
booklet. If you already are a member, please pass it to a
relative or friend, you may save someone else's sight.
Administration:
Email:
Website:
Author: David Wright FIAM Chief Executive Officer
International Glaucoma Association
Medical Editor: Keith Barton MD FRCP FRCS FRCOphth
Glaucoma Service Director, Moorfields Eye Hospital
© International Glaucoma Association 2011
Sightline: 01233 64 81 70
Monday-Friday 9.30am-5.00pm
Welcome
The International Glaucoma Association is, as its name
suggests, primarily a provider of information about the
group of eye conditions known as glaucoma. This guide
has been written to give you an introduction to ocular
hypertension which is raised pressure within the eye and
a significant risk factor for glaucoma. Ocular hypertension
is not glaucoma, but as it may lead to glaucoma, it is
often treated to prevent the onset of glaucoma. This
booklet is intended to help you understand your
condition and the reasons for your treatment to help
ensure that you retain useful sight for life.
Many people who develop ocular hypertension will not
go on to develop glaucoma, especially if they are
diagnosed and treated correctly, but this is only the case
if they adhere to the treatment regime prescribed by
their eye specialist and if they attend their follow up
appointments regularly, so that when changes in the level
of intraocular pressure, or the first signs of damage to the
visual field are noted, the treatment can be altered in
order to prevent further damage.
1
This booklet has been provided to you free of charge
because we believe that it is very important for a person
to receive the information they need when they ask for
it rather than to be given a price list. However, we should
be most grateful for any donation you may be able to
make in order to help us maintain this free service in the
long term.
Structure of the eye
Cross section through the eye showing the major structures
Patient Pictures, Health Press Limited (Oxford)
Sclera
Iris
David Wright FIAM
Chief Executive
Pupil
Aqueous Humour
(watery fluid)
Lens
Choroid
Retina
Vitreous Humour
(clear jelly)
Macular
Cornea
Trabecular
Meshwork
Suspensory
Ligaments
Optic Nerve
(sends information
to the brain)
Ciliary Body
(changes the shape of
the lens to help focus)
The eye is shaped like a ball. The tough white outer coat
is called the sclera and its surface is covered by a thin
layer called the conjunctiva. The clear outer layer at the
front of the eye is called the cornea which is covered by
the tear film. Behind the cornea is the iris – the coloured
part of the eye – with the pupil forming a hole in its
centre.
2
3
The space between the cornea and the lens is filled with
a clear fluid, called aqueous humour, which maintains
the pressure in the eye (the intraocular pressure). The
pressure is determined by the balance between the fluid
production inside the eye and its drainage out of the eye.
On the inside of the back of the eye is the retina, which
is the light sensitive layer onto which an image of what
is being seen is focussed by the cornea and the lens
working together. The central area of the retina where
the most detailed vision is to be found, known as the
macula, has a very high density of cells. Further away
from this central detailed vision area is the area of the
retina which is more sensitive to dim light and that also
provides our peripheral vision. Immediately below the
retina is the choroid, which is the layer of the eye that
provides the blood supply to the cells of the retina and
onto which the retina is attached. Light that has passed
through the front of the eye and is focussed onto the
retina is finally converted into a series of complex
electrical impulses by retinal photoreceptor cells known
as rods and cones. These signals pass along the optic
nerve to the back of the brain, where the final image is
processed.
4
What is ocular hypertension?
Ocular hypertension simply means a raised pressure
within the eye in the absence of detectable
glaucomatous damage. It is not glaucoma, although in
many cases people with glaucoma also have a raised
pressure within their eyes and it does mean that
someone with ocular hypertension is at increased risk of
developing glaucoma. This is why it is most important for
people with ocular hypertension to be monitored
carefully in order that any glaucoma that does develop is
detected at the earliest possible stage when treatment is
most effective.
What is meant by ‘raised pressure’?
Broadly speaking, if a large population of people have
their eye pressures measured, the average pressure will
be about 16mm Hg. Two standard deviations above that
average will give an upper limit of ‘normal’ of about
21mm Hg. An eye is considered to have ocular
hypertension if it is consistently above that level. This is
obviously a mathematical calculation, but the risk of
developing glaucoma rises appreciably with rising
pressure and it has been shown that the risk of
developing glaucoma is about 10 times greater over a 10
year period if a person has pressures between 21 and
5
29mm Hg than if the pressure is below 21mm Hg.
This is why everyone with ocular hypertension should
be monitored carefully for the development of glaucoma
and why some people have treatment to reduce the
pressure to a more ‘normal’ level even when they don’t
have glaucoma, i.e. in order to prevent the development
of glaucoma. It is all a question of balancing the risk of
the development of glaucoma against the risk of
treatment.
Latest research suggests that ‘normal pressure’ in a
Japanese population may be considerably lower than for
other racial groups. People of Japanese origin should
therefore be carefully examined in order to exclude the
possibility of glaucoma. It is not yet known if a similar
liability exists for other Asiatic people.
This is situated in the drainage angle between the cornea
(the clear window at the front of the eye) and the iris. In
a ‘normal’ eye there is a balance between the production
and the drainage of this fluid, but in some eyes this
balance becomes disturbed. Most cases of ocular
hypertension occur because the flow of fluid out of the
eye becomes restricted and the pressure in the eye rises.
drainage angle
cornea
flow of
aqueous humour
through the pupil
iris
Flow of aqueous humour
in the eye
ciliary body
What creates pressure within the eye?
Eye pressure (intraocular pressure) is controlled by a
watery fluid called aqueous humour which fills the front
part of the eye. The purpose of the aqueous humour is to
provide nutrients to the structure of the eye and to
remove waste products. This fluid is made in the ciliary
body (a ring of tissue behind the coloured part of the
eye, which is called the iris). It flows through the pupil
and drains away through tiny drainage channels called
the trabecular meshwork.
conjunctiva
collector channel
trabecular
meshwork
cornea
Outflow of aqueous humour
through the drainage angle
iris
7
6
Are some people at increased risk of
developing ocular hypertension?
Yes, there are several risk factors which make the
development of ocular hypertension more likely and they
tend to be cumulative in their effect.
Age:
Ocular hypertension becomes much more common with
increasing age so regular testing from about the age of
40 is recommended.
Join Us
and help save sight
By joining us, you can keep up to date with the latest news and information
about glaucoma and other eye conditions, as well as helping to support
our work and fund research
Application Form
Your details:
Race:
People of African-Caribbean origin are more likely to
develop ocular hypertension than people of a European
origin. The condition also tends to develop at an earlier
age so regular testing from about the age of 30 is
advisable.
Family History:
It is unlikely that a person will be aware of a history of
ocular hypertension within the family, but any history of
glaucoma in a close blood relative leads to an increased
risk of developing glaucoma.
More information can be found in the IGA leaflet titled:
‘Ocular Hypertension and your relatives’.
Name _________________________________________________________________
Home Address _________________________________________________________
Postcode ______________________________________________________________
Tel. No. ________________________ Email _________________________________
As a charity we are able to reclaim tax on donations
and subscriptions. If you are a UK taxpayer and
would like to help in this way please tick the box and
sign the declaration.
Gift Aid Declaration: (please tick) I want to Gift
Aid all donations I make to the International Glaucoma Association.
I am a UK taxpayer and want the IGA to claim back the tax on all my
contributions made for this tax year and years prior to the year of this
declaration, as per government guidelines, until further notice.*
Signed ____________________________
8
Date _____________________________
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gains tax at least equal to that reclaimed by us on your donation.
Please indicate membership type (tick one box only)
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debit/credit card (£15.00 if you pay by Direct Debit), you will receive:
● quarterly newsletters featuring the latest facts and viewpoints about
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year with glaucoma specialist speakers
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OHAG/6.11
To help us support you, please fill in the information below:
Which eye condition have you been diagnosed with?
Myopia
When were you diagnosed?
Year of birth
Where did you hear of the IGA?
Where did you pick up our literature?
If you have joined on behalf of someone else, please let us know who.
The International Glaucoma Association is registered under the Data Protection
Act 1998 of the United Kingdom. Your information will be held on a database
within the UK. The database will be administered and controlled by the IGA.
By completing this request form you agree that we may use the information
you have given in the following way:
● To maintain records of donations and requests for information.
● To use for future requests for support.
Only the IGA will have access to your information. It will not be disclosed to
other third parties except to the extent required by the laws of the United
Kingdom.
International Glaucoma Association
Woodcote House, 15 Highpoint Business Village
Henwood, Ashford, Kent TN24 8DH
Very short sight (high myopia) is a risk factor for raised
IOP.
Previous eye injury
Any previous eye injury, especially a blunt injury, can
cause damage leading to a raised IOP even years after it
occurred. Regular routine eye health checks are a wise
precaution.
What should I do if I fall into one or more
of these risk categories?
As has already been discussed, ocular hypertension is a
major risk factor for the development of glaucoma. If
ocular hypertension has already been diagnosed, then it
should be expected that regular routine eye
examinations will be needed in order to make sure that
the condition has not developed into glaucoma. These
routine examinations may be carried out at the hospital
or they may be carried out by an optometrist depending
on the level of pressure and whether or not treatment
has been prescribed.
Telephone: 01233 64 81 71 • Email: [email protected]
www.glaucoma-association.com
© International Glaucoma Association 2011
Charity registered in England & Wales No. 274681 and Scotland No. SC041550
13
The central corneal thickness is likely to be measured
once a raised IOP has been identified because a thick
cornea tends to lead to an overestimate of the pressure,
whereas a thin cornea tends to lead to an underestimate.
Once the central corneal thickness is known then
allowance can be made if necessary.
However, anyone who is in one or more of the risk
categories mentioned above should have an eye
examination every year or two at an optometric practice
(opticians) in the first instance, which includes all three
glaucoma tests, so that if glaucoma has developed, it is
detected at the earliest possible stage. An onward referral
can then be made as required.
The three tests are:
Ophthalmoscopy:
An examination of the optic disc at the back of the eye
with a special torch or a slit lamp
Tonometry:
A measurement of the pressure within the eye (the
intraocular pressure)
Perimetry:
A check of the visual field to see if there are any signs of
sight loss in the off-centre part of the vision which could
be a sign of the development of glaucoma
14
How is ocular hypertension treated?
It is not appropriate to treat all cases of ocular
hypertension, but if the risk of development of glaucoma
is considered to be significant, the ophthalmologist may
decide that the balance of risks and benefits is such that
treatment is appropriate. If this is the case, the most
usual type of treatment to be prescribed is eye drops
that control the pressure within the eye, (these are the
same drugs that are used to control glaucoma) by either
reducing the amount of aqueous humour being produced
by the eye (the ciliary body) or increasing the rate of
drainage.
There have been major advances in these forms of
treatments in recent years and eye drops are now more
effective and have fewer side effects than those that
were previously available.
How should I take my eye drops?
It is worth getting into a routine, so that the drops are
not forgotten. For instance, if you keep the bottle of
drops by your toothbrush, you will remember to put the
drops in when you brush your teeth.
15
There are various ways to put drops in the eye. One of
the simplest is to sit in front of a mirror, pull down the
lower lid and let the drop fall into the space between the
eye and the lid.
Close your eye and gently press on the inside corner of it
with a finger for one to two minutes. This will help to
slow the rate at which drops drain out through the tear
duct into your system and keep them in your eye, where
they are needed. Eye drops drain away through the tear
ducts into your nose and then are swallowed, which is
not normally harmful but which may lead to unwanted
side effects in susceptible people.
Another way of putting in your eye drops is to tilt your
head backwards while sitting, standing, or lying down.
With your index finger placed on the soft spot just below
the lower lid, gently pull down to make a space between
the eye and the eyelid. Let a drop fall into the space.
Instilling eye drops
16
Closing the tear duct
Photos by Rachel Ganszczyk
Tips:
If you take more than one type of drop, it is important
to leave at least 10 minutes between each drop to
prevent the second drop washing out the first.
If you are uncertain if a drop has gone into the eye, try
storing your drops in the door of the refrigerator (not the
freezer). It is easier to feel the eye drop going into the
eye when it is cold than when it is at room temperature
(please check with your pharmacist or the drug
information leaflet if the eye drops can be stored in
the refrigerator).
17
Can I continue to drive with ocular
hypertension?
Ocular hypertension is not glaucoma and there is no
requirement to inform the Driver and Licensing Authority
(DVLA) about the condition, unless it develops into
glaucoma in both eyes (in which case you are required
by law to inform the authorities). Nevertheless, it is
important that your general eyesight is good enough to
allow you to drive, so if you have any doubts it is best to
ask your optometrist or ophthalmologist.
What if my ocular hypertension cannot
be fully controlled?
Ocular hypertension itself does not damage the vision,
but if it develops into glaucoma then there is a risk to
sight. More than 90% of people diagnosed with
glaucoma today will retain useful sight for life. If you
have been diagnosed with ocular hypertension and have
received the appropriate level of monitoring, then any
glaucoma will have been detected at a very early stage
when little damage to the field of vision will have
occurred. At the point at which ocular hypertension has
developed into glaucoma, the consideration of risk and
benefit of treatment changes and there are a number of
treatment options available which would not normally
18
be suggested for a person with ocular hypertension
unless the level of the intraocular pressure were very
high. It would therefore still be reasonable to expect to
retain useful sight for life, although the treatment and
monitoring regime will inevitably change.
If you would like to find out more about
ocular hypertension or glaucoma,
please contact Sightline (helpline) on
01233 64 81 70
or by email at [email protected]
or visit www.glaucoma-association.com
Mission & Vision:
The International Glaucoma Association is the charity for
people with glaucoma, with the mission to raise
awareness of glaucoma, promote research related to
early diagnosis and treatment and to provide support to
patients and all those who care for them.
Our vision is to ensure that all people with or at risk of
glaucoma have the knowledge and access to care that
will enable them to maintain a good quality of life.
To find out more about the IGA, or to make a donation,
please contact us on 01233 64 81 64
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Other booklets
Available from the
International Glaucoma Association:
Glaucoma - A Guide
Glaucoma - A Greater Understanding
Glaucoma - Babies and Children
Dry Eye Syndrome - A Guide
Cataracts - A Guide
A full list of references and information sources used in
the compilation of this leaflet is available on request by
phone: 01233 64 81 70 (Sightline) or by email:
[email protected]
We hope that you found this booklet helpful. Your
feedback is important to us, please help us improve our
information by sending us your comments about the
content and format of this publication at
[email protected] or by writing to us at the address
shown on the back of this booklet.
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