Tests and treatments

You have a natural lens inside your eye that helps you to see. The lens should be transparent like glass but a cataract makes the lens cloudy. Not all cataracts need an operation and sometimes glasses will improve the vision. Cataracts can only be completely cured by surgery - no other medical treatment is currently available. During cataract surgery the surgeon removes the cloudy lens from your eye and may replace it with a man-made lens.

Read more about cataract surgery

Counselling at the Richard Desmond Children’s Eye Centre at Moorfields provides a safe and confidential space where children and young people from the age of three to eighteen can talk to someone who will listen, empathise and help you to better understand what you’re going through. It can lead to improvements in family relationships, friendships and self-esteem, as well as enabling you to better process your thoughts and regulate your emotions.

Read more about counselling for children and young people.

In glaucoma, the pressure in your eye is too high, which damages the delicate optic nerve sending information from your eye to your brain. High pressure can sometimes be treated with eye drops, but they have to be used all your life and might not get the pressure low enough to be safe for your eye. In young people, it is usually better to do an operation. If the operation is very successful you might not need to use drops any longer! 

Read about glaucoma surgery.

The information you find here has been put together especially for children and young people with sight loss and their families.  

Read more about services for children and young people with sight loss and their families.

The information you find here has been put together especially for children and young people with sight loss and their families at Bedford. 

Read more about services for children and young people with sight loss and their families at Bedford. 

A general anaesthetic, often referred to as simply a “GA”, is used to make you fall asleep and feel no pain during an operation. You will be given the anaesthetic by a specially trained doctor called an anaesthetist.

 What happens during a general anaesthetic?

When under general anaesthetic you sleep more deeply then you normally do at night. So it’s very important that you do avoid eating for some time before the GA, because if you were to be sick while under anaesthetic there is a risk that the fluid could enter your lungs and make you ill.

To help you breathe more easily during the procedure you will have a tube placed in your mouth. It’s for this reason that the doctor needs to know about your teeth and will ask if you have any caps or crowns and where precisely in your mouth they are.

The most uncomfortable part of the anaesthetic is the small needle which is put into a vein in the back of your hand before the operation. Thirty minutes before the needle is inserted the nurse will apply a special numbing cream called Ametop to ease the discomfort.

Your parents can stay with you until you fall asleep but will not be able to come to the operating theatre. Once you are asleep you will go into the theatre for your operation and will afterwards be brought back to the ward with the nurse. When you are starting to wake up the nurse will bring your parents to see you again.

Sometimes you will wake up after a GA with a sore throat. This can be due to the tube that is used to help you breathe during the operation. The soreness usually disappears after a day and can be relieved by sucking boiled sweets.

Some people feel sick after having a GA, but this depends on the individual and the type of surgery they have had. Let the anaesthetist know if you suffer from motion sickness or have previously been sick after an anaesthetic, and they will give you some medication to help.

Does it work?

Yes. Because the GA makes you fall asleep and lie still, the doctor is able to carry out the operation without interruption.

Trouble spots

Although having a GA is not in itself dangerous, any procedure can still involve a small degree of risk. Every measure is taken to make sure that the risk is absolutely minimal. An anaesthetist will always carefully assess your suitability and decide whether you are healthy enough to undergo a GA. The medical staff who carry out this procedure are highly trained and experienced, and will take every precaution to guarantee your safety at all times.

What is it?

When an optometrist, or optician, gives you a sight test, their examination will include refraction. Refraction is the part of the test which checks the health of your eyes and finds out what kind of glasses will correct or assist your vision. If you are a patient in a hospital and are sent for refraction it will be purely to identify which glasses you need.

When is this test carried out?

Refraction is done when the ophthalmologist wants to know if your vision can be improved, for example, after a cataract operation when your glasses are likely to need changing. A refraction can also help the ophthalmologist decide whether or not to operate. If new glasses alone can improve the vision, then an immediate operation may not be necessary.

What does it offer?

A refraction will show if your vision can be enhanced with glasses. It can also reveal any changes in the eyes, such as the development of cataract.

What happens during the test?

You will be asked to read a letter chart a few metres away.  This will most likely be the very familiar Snellen chart, which has rows of letters decreasing in size from the top of the chart to the bottom. Your level of vision is measured by the smallest line of letters you can read from a distance of six metres. For younger children these charts can be modified so that they use pictures instead of letters, or the child may be asked to match a single letter to one they are holding themselves.

You will also be asked to read from a page of print.  This will have paragraphs with different sizes of text.  Small children may be shown pictures of different sizes to name.

The optometrist will then ask you to put on a trial frame.  This is a special sort of spectacle frame that can hold the different lenses so that the optometrist can check which ones give you the best vision.  Whilst you are wearing the trial frame you will be asked to look in a certain direction while a light is shone into your eyes.  After this, you will be shown different lenses and asked which ones make your vision clearest.

Younger children may not have to wear the trial frame and they may also need to have “dilating drops” put in before the refraction is done.

What is it?

The electroretinogram (ERG) test is an eye test that aims to discover how well the retina at the back of your eye is working, and whether it has any kind of disease.

Why would I need to have an ERG?

The ERG test is very helpful in assessing any problems with your retina that you may have inherited, such as retinitis pigmentosa, or damage to it resulting from drugs etc.

 The test gives the ophthalmologist vital information to help them decide the best way to treat your eye.

When light falls on the retina it stimulates many different types of cells which in turn produce a variety of electrical responses. Studying these responses can help us detect which cells are healthy and which are not.

Your retina has cells called rods and cones which process light. During the ERG test, these cells release tiny amounts of electricity in response to flashes of light. If we know exactly how much light enters the eye and how much electricity comes out, we can figure out how the rods and cones are working.

What happens during an ERG? 

To prepare you for the ERG test, drops are placed in your eyes to dilate the pupils. These drops are the same as the ones doctors routinely use for eye examinations. You will then be asked to sit in a dark room for 30 minutes to allow your pupils to dilate. During this time, your retina will also steadily adapt to the dark and become more sensitive to light, which means it will give a stronger response when tested.

After your eyes have adapted to the dark, anaesthetic drops are given and a contact lens is placed on your eye. Often both eyes are tested at the same time. Once the contact lens is in place, it is recorded how your retina responds to a series of blue and red lights. This part of the test may take 30 to 45 minutes. The total time for the ERG test, including the period of dilation and adaptation to the dark is approximately one and a half hours.

An examination under anaesthetic, known as an EUA, is when doctors look closely at your eye but don’t necessarily operate on it.

What happens during an EUA?

If your eye is to be examined in this way you will be admitted to a children’s ward, given a general anaesthetic and taken to the operating theatre for the EUA.

EUAs are completed in a day. This means you will be admitted, examined and allowed to leave on the same day. 

Once the EUA has ended you will be taken to the recovery area.  When you wake up the nurse will bring your parents or carer to you. The doctor will then come and discuss the findings from the EUA and any future treatment you might need. Everyone is different, but usually you will need to remain on the ward for at least two hours after having an EUA. During this time you will be encouraged to drink fluids, eat some food and pass urine.

After the anaesthetic, you may feel sick for the first 24 hours. You should still try to drink plenty of liquids during this period.  As long as you do so, it doesn’t matter too much if you eat very little for the first couple of days following the EUA, during which you may feel uncomfortable. When you get home, whoever is looking after you can give you regular pain relieving medicine to help ease some of this discomfort.

Does it work?

EUA are performed for a variety of reasons. Generally, an EUA is done when it would be uncomfortable for you to be examined whilst awake.  Because the general anaesthetic makes you fall asleep and lie still, the doctor is able to have a good look at your eye without interruption.

Trouble spots

When doctors perform an EUA they sometimes discover a problem that requires an operation straight away. This is most likely for children who have glaucoma, where EUAs are regularly performed to check the pressure inside the eye. In a case like that, the operation would be completed while you are still asleep under the anaesthetic.

What is it?

Ultrasound is sound with a very high pitch. So high that it cannot be heard by people, or even by dolphins or bats.
A probe resembling a small wand, and emitting ultrasound, is used to examine the eye. The ultrasound 'bounces off' the eye’s internal structures to create echoes which then return to the wand. A computer uses the echoes to form a picture that the doctor performing the scan can interpret.

When is this test carried out?

Usually an ophthalmologist only needs light to examine an eye. But this can prove difficult if there is blood in the eye, or a cataract. In these cases, an ultrasound test is performed instead. Ultrasound is also used to measure an eye’s length.

What does it offer?

An ultrasound test will give the ophthalmologist vital information to help them decide the best way to treat your eye.

What happens during the test?

Examinations take just a few minutes to complete and are painless, with no anaesthesia required. Ideally the head should kept as still as possible.

Children are examined while seated. Babies or young infants are generally examined whilst held on a parent’s lap but may be examined in a portable car seat or buggy. 

A probe is smeared with a liquid gel and moved over the closed eyelid. The probe emits pulses of ultrasound into the eye and surrounding tissue. During the brief intervals of time between each pulse, the probe receives any echoes which scatter back towards it. The echoes are converted into electric signals which are displayed on screen as real-time images of the eye in cross section.

The operator performing the scan can make diagnoses from the moving images on the screen and digitally store any selected images.

Measurements of eye structures are generally made from any stored images once the examination is over. A report is produced immediately following the examination for patients to take back to the referring ophthalmologist.