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RNIB, supporting people with sightlossRegistered charity number 226227 (England and Wales) and SC039316 (Scotland)Eye condition fact sheet: Retinopathy of prematurity

Retinopathy of Prematurity (ROP)

What is ROP?

Retinopathy of prematurity is when the retinal blood vessels don’t develop normally in babies that are born earlier than their expected date of delivery.

The retina is a delicate tissue made up of light sensitive cells that lines the inside of the back of our eye. The retina converts light that we see into electrical signals that travel along the optic nerve to the brain. The brain interprets these signals so we can ‘see’. The retina is supplied with blood by a delicate network of blood vessels on its surface and by a layer of blood vessels underneath the retina.

Our retina needs a good blood supply to work properly. As a baby develops in the womb, the blood supply for the retina starts to develop around 16 weeks into pregnancy and only finishes around 40 weeks when a full term baby is born. At full term, a baby's blood vessels are fully developed and can keep the baby's retina healthy.

If a baby is born too early then their retinal blood vessels don’t develop completely which can cause problems. Abnormal blood vessels may grow out of the retina and cause scar tissue to form, leading to detachment of the retina which can cause blindness. This damage is known as retinopathy of prematurity and if not monitored or treated at the correct time, can cause vision loss.

What causes ROP?

The reasons why babies develop ROP are complicated, but ROP is more likely to occur in babies that

are born very prematurely - particularly those born before the 28th week of pregnancy

have a low birth weight of less than 1500 grams required oxygen treatment soon after they were born.

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Often premature babies need additional oxygen which is necessary for the baby's survival but this can increase the risk of developing ROP.

Not all premature babies that need oxygen develop ROP. Paediatricians (hospital consultants that specialise in caring for children) monitor levels of oxygen a baby needs very carefully to ensure that enough oxygen is given for the baby’s survival while also taking into account the effects this may have on the baby's eye. Checks for ROP are a regular part of care for all premature babies born before 32 weeks or babies born weighing less than 1500g (3lb).

How does ROP affect the eye?

ROP mainly affects the retinal blood vessels. When the retinal blood vessels haven’t developed completely, the retina isn’t receiving enough oxygen so tries to grow new vessels. However, these new blood vessels grow abnormally and are fragile, can cause scarring and damage to the retina. The most severe forms of ROP are very rare but if left untreated, can lead to retinal detachment and blindness.

There are a few ways of describing the amount of ROP present in the eyes, which includes its location, extent and stage.

LocationThe location on the retina is divided into 3 zones where zone 1 is the innermost and zone 3 is the outermost. The zones are centred around the optic nerve. This is because the blood vessels tend to grow from the area where the optic nerve leaves the eye called the optic disc.

ExtentThe extent of ROP is described using clock hours. This refers to how much of the retina is affected by ROP. If you imagine the retina being divided up like a clock face: if there is ROP present

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from the bottom round to the left hand side, this would be equivalent to 3 clock hours.

StageBroadly speaking there are five stages of ROP. These stages describe what the ophthalmologist (hospital eye doctor) sees when they look into a baby's eyes.

Stage 1: This is where the junction of the central part of the retina that already has blood vessels and the peripheral part of the retina where blood vessels have not yet grown is marked by a demarcation line or a flat white line. Babies with stage 1 ROP usually recover without needing any treatment.

Stage 2: In stage 2, the demarcation line is raised and is more like a ridge. Babies with stage 2 ROP may recover without needing any treatment as well. These babies may require more regular check-ups to monitor progress

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Stage 3: Stage 3 is where new blood vessels start to grow out of the ridge. These blood vessels are very weak and they will cause vision problems if they start to scar. If there is also enlargement and tortuosity of the main normal blood vessels of the retina, this is known as ‘plus disease’. Stage 3 ROP with plus disease usually requires treatment.

Stage 4: In stage 4, the fragile new blood vessels that grow in stage 3 can contract (shrink) causing scarring which can pull the retina away from the back of the eye (partial retinal detachment).

Stage 5: Stage 5 is where the retina can become totally detached from the back of the eye (total retinal detachment). This would lead to permanent loss of vision.

Most babies with ROP only develop stage 1 and stage 2 with only a small number developing stage 3 and needing treatment.

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How common is ROP?

In the UK, about 65 percent of babies who have a birth weight of less than 1251 grams will have ROP. However, the majority of these babies will have mild ROP that doesn’t require treatment. There are only around 6 percent of premature babies that will have advanced ROP requiring treatment (stages 3, 4 or 5).

The incidence of ROP is on the rise as more and more babies now survive when they are born prematurely. This means that there are more babies with ROP. Treatments are now offered at an earlier stage than in the past so the sight threatening severe forms of ROP (stage 4 and 5) are rare.

How is ROP diagnosed?

All newborn babies that weigh less than 3lbs or 1501g or babies born at or before 32 weeks of pregnancy will have at least one eye screening examination. An ophthalmologist will perform the screening and can diagnose retinopathy of prematurity. The first eye examination is done a number of weeks after birth. The timing of this is determined using a table based on the baby’s gestational age at birth.

Eye drops will be placed into the baby's eyes to enlarge the pupil which is necessary for the ophthalmologist to view the retina inside the eye clearly. Anaesthetic drops are also used so that the baby doesn’t feel any pain.

The ophthalmologist will use a special lens and light to view the retina which often only takes a few minutes. Often the doctor will use a speculum or a clip to help keep baby’s eyelids open while looking in the eye. They may also use an indentor which is like a tiny rod that is pressed gently on the eyeball so that the doctor can have a thorough look inside the eye. It’s not uncommon for your baby to cry during the procedure. Some centres may use a special camera to take pictures of the retina.

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This screening will happen weekly or fortnightly until the risk of developing ROP requiring treatment has passed. If a baby has some signs of ROP then these examinations will continue until your baby’s due date.

Further details on timings and frequency of ROP screening for babies can be found in ‘Guidelines for Screening and Treatment of Retinopathy of Prematurity’ produced by the Royal College of Ophthalmologists; this publication can be found on their website at https://www.rcophth.ac.uk/wp-content/uploads/2014/12/2008-SCI-021-Guidelines-Retinopathy-of-Prematurity.pdf

Following the eye examination, the ophthalmologist will then decide whether treatment is required.

What is the treatment for ROP?

Many babies with ROP don't need treatment as it often resolves on its own.

If new blood vessels start to grow then treatment can be used to stop them causing more damage. Some babies will need more than one treatment. Usually treatment is done using a laser machine, but in certain circumstances treatment is done by injecting a drug into the eye. Treatment for ROP can be a distressing time for both parents and baby.

A baby will need to go on a ventilator which is a breathing machine and be intubated where a breathing tube is inserted in the baby’s mouth for treatment; this means that your baby will be unconscious for the whole treatment. This is to ensure they are completely still and don’t experience any pain while the treatment is happening. Your baby’s heart and breathing are carefully monitored during the treatment. The treatment can take between 1 and 2 hours to complete. Most babies stay on the breathing machine for a day or two but sometimes can take longer to come off breathing support.

The treatment uses a laser to make small burns on the retina inside the eye. This can stop the new blood vessels from

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developing. Although the laser helps to safeguard vision, it can affect your baby’s peripheral or side vision.

Once the treatment is finished your baby’s eye may look red and swollen. Eye drops may also be required following treatment for a week or so, but the eye will no longer be painful. The baby's eye will need to be examined in about a week's time to check if the laser treatment has worked. Sometimes, further treatment will be required.

Another possible treatment option that is sometimes required for ROP is anti-vascular endothelial growth factor (anti VEGF). The term 'anti' means ‘against’ and 'vascular' refers to blood vessels. Anti-VEGFs are drugs that stop blood vessels from forming or growing and are given by injection into the eye. In the UK this treatment is for babies who do not respond to laser treatment or who are too sick to go back on the breathing machine. It is still not known what affect anti VEGF injections into the eye might have on blood vessel development elsewhere in a baby, in particular on brain development.

In most babies early treatment is usually successful. This means that the abnormal blood vessels stop developing and a retinal detachment doesn't occur. In some babies the treatment may stop the retina from detaching, but their vision may still be affected; they may not recover all their sight back after treatment.

In a baby with stage 4 ROP, surgical treatment such as a vitrectomy may be done. A vitrectomy procedure involves removing the vitreous gel in the eye and replacing it with a clear solution. The solution then holds the detached retina against the back of the eye. Some useful vision may be preserved by this type of surgery, especially if it is done very soon after stage 4 ROP has developed. Unfortunately, surgical treatment for stage 5 ROP rarely achieves useful vision.

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How will ROP affect vision?

Vision in children develops from when they are born up until they are around 7 years old. It’s not possible for doctors to know what a baby's vision is like until at least 6 weeks after their original due date when vision ‘switches on’. Even then, as vision continues to develop during childhood, it may not be possible to know what a child’s vision is like until they are much older. However, doctors will be able to give an approximate estimate of how well each child is likely to be able to see, based on the health of the eyes, and of the brain.

Vision development depends on the health of the visual nerve pathways in the brain as well as of the eyes. Premature babies can have some areas of brain injury, usually caused by bleeding into the brain soon after birth. Unfortunately, some children who were born prematurely have poor vision due to brain injury, even if their eyes have not been damaged by retinopathy of prematurity.

Babies who have stage 1 and stage 2 ROP may not have any vision problems and therefore won’t usually require regular eye exams by an ophthalmologist. Often babies in Stage 1 and 2 would then only need to have the national vision screening which begins in school age at around the ages of 4-5 years. This is a vision check to make sure vision is developing normally in children. If you have any future concerns about your child’s eyes or vision, you should speak to your GP or optometrist (optician) who would be able to refer your child to an ophthalmologist.

Babies who have stage 3 ROP may be followed up in the hospital clinic according to the centre's protocol as they may be more likely to have eye problems. Babies who have had treatment will be regularly monitored for myopia or short sightedness and whether there are any long term effects from the laser scars which can occasionally affect vision.

It’s likely that babies who have stages 4 and 5 ROP will have significant vision loss. Although vitrectomy surgery is successful in some of these babies, many have a poor visual outcome.

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Although the incidence of ROP is rising due to more premature babies surviving, our knowledge and understanding of the condition has also increased. The number of babies with ROP requiring treatment still remains very small. There have been great improvements in the screening, diagnosis and treatment of ROP which has led to better visual outcomes for these children.

Babies who are born early are at higher risk for having vision problems, which aren't caused by ROP, when they grow older. Some of these problems may include:

Myopia or short sightedness Squint Brain injury

Myopia or short sightedness and squint can normally be corrected with glasses. Vision problems due to brain injury may be severe, and are then apparent at an early age. However, they may be mild and subtle and are then only recognised at an older age. Some of these milder problems consist of an inability to cope with a crowded visual environment (“crowding”), and reduced awareness of the lower visual field which can result in clumsiness while walking.

Coping if your child has sight problems

On hearing that your child has a sight problem you may feel like your world has been turned upside down. Different people respond in different ways but it’s natural to experience many emotions which may include shock, fear, grief, sadness or despair. All of these feelings are quite common and could be part of the process you will go through during the early weeks and months.

You may have left the consulting room in a daze and may not have heard all the words that were said to you during the consultation. You may be asking yourself what happens next and what the future holds for your child.

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Different feelings come and go and can catch up with you when you least expect it. All the while your child’s need for food, love, warmth and security continue to demand your energy, care and attention. But the first step is to make sure you have access to all the information and help that is available.

You probably have a million different questions. You will want to know which organisations can help you, what resources are available or simply want to know “what do I do next?” You may also want to meet other parents who have been through a similar experience.

Your local authority (LA) should have at least one qualified teacher of visually impaired children (QTVI) to work with you and your child both at home and at school. A QTVI are qualified teachers who can provide support with development, play, learning and education. At an early stage, ask your local authority to put you in contact with a QTVI. They will support you and your child as soon as a vision impairment is suspected or diagnosed. If you have difficulty getting help, or need the details of the specialist teacher in your area, contact RNIB Helpline on 0303 123 9999.

Sources of support

If you have questions about anything you’ve read in this factsheet, or just want to speak to someone about your eye condition, please get in touch with us. We’re here to support you at every step.

Our Helpline is your direct line to the support, advice and services you need. Whether you want to know more about your eye condition, buy a product from our shop, join our library, find out about possible benefit entitlements, or be put in touch with a trained counsellor, we’re only a call away.

It’s also a way for you to join RNIB Connect, our community for anyone affected by sight loss. RNIB Connect is free to join and

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you’ll have the chance to meet other people with similar experiences in our helpful, welcoming and supportive community.

Give us a call today to find out how we can help you. RNIB Helpline0303 123 9999helpline@rnib.org.uk

We’re ready to answer your call Monday to Friday 8am to 8pm and Saturday 9.30am to 1pm. You can also get in touch by post or by visiting our website:

RNIB105 Judd StreetLondon WC1H 9NErnib.org.uk

Other useful organisations

Bliss is the UK’s leading charity for babies born premature or sick. Helpline: 0808 801 0322Email: hello@bliss.org.uk

www.bliss.org.uk

LOOK (National Federation of Families with Visually Impaired Children)Tel: 01432 376314Email: info@look-uk.orgwww.look-uk.org

Guide Dogs - Children and Young People’s service (formerly Blind Children UK)Tel: 0800 781 1444 http://www.guidedogs.org.uk/

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Visually Impaired Children Taking Action (Victa) Tel: 01908 240831 Email: admin@victa.org.uk www.victa.org.uk

The Royal College of OphthalmologistsROP Guidance

https://www.rcophth.ac.uk/wp-content/uploads/2014/12/2008-SCI-021-Guidelines-Retinopathy-of-Prematurity.pdf

We value your feedbackYou can help us improve our information by letting us know what you think about it. Is this factsheet useful, easy to read and detailed enough – or could we improve it?

Send your comments to us by emailing us at eyehealth@rnib.org.uk or by writing to the Eye Health Information Service, RNIB, 105 Judd Street, London, WC1H 9NE.

This factsheet has been written by the RNIB Eye Health Information service. Our factsheets have been produced with the assistance of patient and carer input and up-to-date reliable sources of evidence. The accuracy of medical information has been checked by medical specialists. If you would like a list of references for any of our factsheets, please contact us at eyehealth@rnib.org.uk

All of our factsheets are available in a range of formats including print, audio and braille.

Last updated: March 2018Next review: March 2021

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