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Home , Anophthalmia, Choroid, Coloboma, Pupil

Coloboma Factsheet Contents 3 What is ? 3 How do we see with our ? 3 Which parts of the can coloboma affect? 3 4 zonules 4 and (chorioretinal) 4 4 4 What causes coloboma to form inside the eye? 5 Does coloboma affect vision? 5 Iris coloboma 5 Lens coloboma 5 Chorioretinal coloboma 6 How is coloboma diagnosed? 7 What is the treatment for coloboma? 7 Can coloboma lead to other eye health problems? 7 8 8 Choroidal neovascularisation (new blood vessels) 8 9 What other health problems can affect some children with coloboma? 9 Coping with sight problems relating to coloboma 10 Further help and support 10 Sources of support 11 Other useful organisations 12 We value your feedback

2 What is Coloboma? Coloboma means that part of one or more structures Choroid inside an unborn baby’s eye does not fully develop Iris during . This underdeveloped tissue is normally in the lower part of the eye and it can be Optic small or large in size. A coloboma occurs in about 1 in disc 10,000 births and by the eighth week of pregnancy. Macula Lens Coloboma can affect one eye (unilateral) or both eyes zonules (bilateral) and it can affect different parts of the eye. As coloboma forms during the initial development of Choroid the eye, it is present from birth and into adulthood. Lens

Retina How do we see with our eyes? Iris Light enters our eyes by passing through our cornea, our pupil, (the hole in the middle of the iris), and Diagram of cross section of eye (labels cornea, lens, iris, our lens so that it is sharply focused onto the retina vitreous humour, macula, retina, choroid, optic nerve) lining the back of our eye. The retina is made up of light sensitive cells that convert light into electrical impulses which then travel along the optic nerve to our . Our brain processes these signals so that we are able to “see” the world around us.

Which parts of the eye can coloboma affect? Opposite is a diagram of the eye showing the main structures that can be affected by coloboma Iris Iris Coloboma can affect the iris, the tissue that gives Pupil you your eye colour. Your pupil may look oval if the Coloboma coloboma is partial but if more of the lower iris is missing, your pupil will look more keyhole shaped. Photo and diagram of iris coloboma 3 Lens zonules folds round, it should join together at the bottom from Coloboma can also affect the supporting fibres of the the back to the front along a seam-like structure called lens, which are called the lens zonules. The zonules hold the embryonic fissure. If this seam doesn’t join completely, your lens in place, just behind your iris. If a section of there will be tissue missing at the bottom of the structures zonules is defective or missing, the lens is not held as being formed, leading to coloboma. The structure in the strongly all the way round. This alters its shape and as eye that is affected by coloboma relates to the part of the a result, there will be a notch or dent in the lens. This is embryonic fissure that didn’t close properly. Coloboma may often referred to as lens coloboma, despite the fact that only affect the front of a baby’s eye if most of the fissure none of the lens tissue itself is missing to form the notch. closed up. However, it may also affect structures further back in the eye too, if less of the fissure closed properly. Retina and choroid (chorioretinal) Most cases of coloboma appear without any previous At the back of your eye, the retina and the choroid family history, although in some families coloboma can can be affected by coloboma. This is known as be inherited, or could be caused by environmental factors a chorioretinal coloboma. The choroid is the such as certain drugs or infections during pregnancy. layer of tissue behind your retina and it contains A fault in the gene PAX6 has also been found to cause blood vessels that keep your retina healthy. coloboma. If a child is found to have a coloboma, the Optic disc ophthalmologist (hospital eye doctor) may ask to examine Coloboma can also affect the optic nerve where it leaves both parents’ eyes too. This is because either one of them the back of your eye, an area known as the optic disc. may have a coloboma as well but be unaware of it because they have no visual problems. If there is coloboma in Eyelids your family, you may wish to talk with the hospital staff coloboma is less common. Although gaps in or your GP about and speak to a genetic the eyelids are still known as coloboma, they are not counsellor about the genetic inheritance of the condition. caused by the same development problem in pregnancy Some families find out about the genes involved in their that leads to coloboma of structures inside the eye. child’s coloboma, while others do not. This is because not all the genes relating to coloboma have been identified What causes coloboma to form inside the eye? yet. Research is going on to find out more about these Coloboma forms during pregnancy while a baby is genes. There is more information about this research developing. During the second month of pregnancy, the on the MACS (, and buds that become the eyes develop and fold round to form Coloboma Support) website listed in the further help the shape and structures of the eye. As the developing eye and support section at the end of this information.

4 Does coloboma affect vision? Chorioretinal coloboma The effect that coloboma has on vision Someone with chorioretinal coloboma, where the choroid depends on which structures of the eye are and the retina are involved, may not be aware of any involved and how much tissue is missing. visual symptoms. However, the more retinal tissue that is missing, the more their sight is likely to be affected, Iris coloboma usually in the upper region of their field of vision. Both children and adults with only iris coloboma will If the chorioretinal coloboma is large or there is optic disc probably have fairly good vision. However, iris coloboma is coloboma, they are likely to have poor central vision. This likely to cause light sensitivity, (also called ), will make activities such as reading, writing and watching in bright conditions. This is because the iris is made television more difficult. If both eyes are affected by optic of muscle that controls the amount of light entering disc coloboma, they may also have , meaning the eye by changing the size of the pupil. If too much that their eyes move constantly and uncontrollably. light enters the eye because some of the iris is missing Vision that is affected by these types of coloboma and not working effectively, the glare that results can cannot be corrected with glasses or contact lenses. cause discomfort and affect the quality of vision. Tinted glasses, sun hats or sun blinds in cars can help to relieve You can find out more about nystagmus from light sensitivity. Your optometrist (also known as your our website rnib.org.uk/eyehealth or by optician) will be able to offer further advice about this. calling our Helpline on 0303 123 9999.

You can find out more about light sensitivity It may be hard to tell what effect coloboma will have from our website rnib.org.uk/eyehealth on a child’s sight until they are older when they will or by calling our Helpline on 0303 123 9999. be able to say more accurately how well they can see. Some children with coloboma may also have focusing Lens coloboma problems that aren’t caused by the coloboma itself, If the lens of the eye is affected by coloboma, vision is such as being short-sighted or long-sighted, so their affected because of the change in lens shape caused optometrist may advise that they need to wear glasses. by the notch or dent. There may also be some degree Although glasses and contact lenses are unable of cataract in the affected eye, which means the lens is to improve any sight problems that are caused by cloudy instead of being clear. The treatment for cataract coloboma, it’s important for children to have any can be found in the “Can coloboma lead to other eye focusing problems corrected to allow their sight to health problems?” section further on in this information. develop as fully as possible. Therefore, it’s important

5 that children continue to have regular eye examinations How is coloboma diagnosed? as often as is advised by their optometrist. Coloboma is normally diagnosed when a baby is born or Where coloboma affects a person’s sight, there are specialist in a very young child. Iris coloboma can usually be seen support services which can help them. If they still have as a keyhole shaped pupil when looking at their eyes. difficulty seeing detail with their glasses or contact lenses, Some people with iris coloboma also have differently they would benefit from having an assessment in a low coloured eyes which is called iris heterochromia. This vision clinic where a low vision specialist can prescribe means that there is a different amount of pigment magnifiers to use to make the most of the sight that that determines eye colour on the iris of each eye. they have. An ophthalmologist, optometrist or GP can If you notice these features in your child, your GP refer them to their local low vision clinic which is often or optometrist would normally refer them to an located in the hospital eye department. It is important ophthalmologist. An ophthalmologist will examine for children to have regular low vision assessments their eyes in detail to check if there is coloboma in any because their vision needs change as they grow up. other part of their eye. To do this, they normally use an instrument called an ophthalmoscope which they hold You can find out more about the practical help close to your child’s eye but without touching it. They may we can offer children, young people and families also carry out other tests as well, which may include: from our website rnib.org.uk/practical-help or by calling our Helpline on 0303 123 9999. • measuring what your child can see to the sides, above and below when looking straight ahead. This is a It’s important for the local authority to be aware of measure of their visual field and it does require your any specialist educational needs a child has so that child’s co-operation to give accurate results; a plan can be put in place to provide for this. Local • looking at the different structures of their eyes using authorities should also be able to provide a specially a special microscope called a slit lamp; trained qualified teacher of children and young people with vision impairment (QTVI) to work alongside children • optical coherence tomography (OCT) which provides the and their families. They can provide information on ophthalmologist with an image of the different layers of development, play, education and many other issues. the retina but without touching the eye; • CT (computerised tomography) or MRI (magnetic You can find out more about education resonance imaging) scans so the ophthalmologist professionals from our website can examine the structures of the eye. rnib.org.uk/professionals or by calling our Helpline on 0303 123 9999

6 If a young baby is suspected of having coloboma, it For other types of coloboma inside the eye, there is no may be necessary to give them a general anaesthetic treatment at present. However, other eye health problems so that the ophthalmologist can examine their that are associated with coloboma, such as glaucoma, eyes thoroughly without distressing them. retinal detachment, choroidal neovascularisation and cataract can be treated. It’s important for people with If someone has a chorioretinal coloboma, it might appear coloboma to have regular eye examinations with their that they have a white pupil instead of the optometrist, who will be able to check for any changes normally seen in pictures taken using flash photography. to their eye health. An optometrist will advise how The usual red reflex is caused when the flash lights up often an is necessary. A person with the retina with its rich blood supply at the back of the coloboma who experiences any new symptoms or eye. If there is a gap in the retina due to coloboma, the concerns should have their eyes examined straight away. red reflex will be replaced with a white one. A white pupil is known as leucocoria. If you notice that your child has the appearance of leucocoria at any time, it’s important Can coloboma lead to other eye that their eyes are examined by an optometrist or health problems? ophthalmologist urgently because there are other serious Sometimes, coloboma can increase the risk of other eye eye conditions that can give a similar appearance. conditions. An ophthalmologist or optometrist will be able to monitor the eye health of anyone with coloboma and advise What is the treatment for coloboma? them further about these conditions. Some are listed here. If a child has coloboma, they will receive specialist Glaucoma care at hospital during the early years to monitor Glaucoma is an eye condition where your optic nerve the effect of the coloboma and their eye health. The is damaged by the pressure of the fluid inside your eye. frequency of these checks will depend on their needs. There may be an increased risk of glaucoma in people Many children and adults with iris coloboma will require with coloboma, because there may be a malformation no treatment. However, some have a special of the drainage meshwork inside the eye that helps to fitted that covers the keyhole shaped pupil and makes maintain the eye’s pressure. Treatment for glaucoma it look round. This improves the cosmetic appearance can be given to lower eye pressure to prevent further of the eye as well as reducing light sensitivity. For damage to the optic nerve and preserve sight. some people, surgery is an option, where the gap in the iris is sewn together to correct the pupil shape You can find out more about glaucoma from and reduce light sensitivity. Your ophthalmologist will our website rnib.org.uk/eyehealth or by be able to discuss these options with you further. calling our Helpline on 0303 123 9999.

7 Retinal detachment Cataract There is an increased risk of a retinal detachment if there Some people with coloboma will develop a cataract at is coloboma of the retina, choroid or optic disc at the an earlier age than people without coloboma. Having back of the eye. This means that the retina near to the a cataract means the lens inside your eye has become coloboma is more at risk of becoming detached away cloudy. This cloudiness can cause symptoms such as from the back of the eye. A retinal detachment can be blurred or misty vision, colours appearing dull and treated with surgery, but this does need to be done glare in your vision, particularly with night driving. If urgently to prevent further sight loss in that eye. The vision cannot be improved properly with glasses, adults symptoms of retinal detachment include and with can be treated using surgery to remove flashes of light in your vision and some people notice a the cloudy lens, replacing it with a clear artificial one. curtain effect coming down, up or across their vision. This procedure can be more complex for a child with cataracts and coloboma so the ophthalmologist will You can find out more about retinal detachment carry out an in-depth assessment before discussing from our website rnib.org.uk/eyehealth or ways to manage the condition with the child’s family. by calling our Helpline on 0303 123 9999.

Choroidal neovascularisation (new blood vessels) You can find more information about cataracts Some people with chorioretinal and optic disc coloboma on our website rnib.org.uk/eyehealth can develop new blood vessels in the choroidal layer or by calling our Helpline 0303 123 9999. behind the retina at the back of their eye. These new vessels are weak, so they leak and bleed easily, which can damage your vision. Choroidal neovascularisation is a rare complication of coloboma at the back of the eye but it can be treated with anti-VEGF injections. Anti-VEGF injection The body produces a chemical which encourages the growth of these abnormal blood vessels. By interfering with this chemical using drugs called anti-vascular endothelial growth factors (anti-VEGFs), new growth and leakage can be reduced. Anti-VEGFs are given as an injection into the white part of the eye and offered as an out-patient procedure.

8 What other health problems can affect Coping with sight problems some children with coloboma? relating to coloboma Most children with coloboma do not have It’s completely natural to be concerned if you or your child any other eye or health problems. has coloboma and normal to find yourself worrying about what it means now and in the future. You or your child Some children with coloboma also have other eye may have normal vision or there may be some degree of problems such as microphthalmia (where the whole sight loss. The extent of sight loss will relate to what type eye is small) and anopthalmia (where the eye has not of coloboma is present, how large it is and whether it is developed at all). Some children with coloboma have found in one or both eyes. For a child, it’s difficult to predict other health problems that need to be assessed and to what extent their vision will be affected by coloboma in so, for this reason, the ophthalmologist may carry out the long term. Therefore it’s important for them to attend additional tests to check your child’s general health. their hospital eye clinic appointments as advised by their Coloboma can be part of a syndrome, where ophthalmologist, and to have regular eye examinations other parts of the body are also affected. CHARGE as advised by their optometrist, to ensure they have the syndrome is a rare condition and is one example greatest chance of developing the best vision they can. It’s of a syndrome involving coloboma. The letters also important for adults to have regular eye examinations represent different features of the condition: too, with either an ophthalmologist (if still under hospital care) or an optometrist at least every two years, or as • Coloboma recommended, to ensure that their eye health is monitored. Heart defects • It can sometimes be helpful to talk about how you • Atresia, or blockage, of the nasal passages (choanal are feeling with someone outside of your circle of atresia) friends or family. At RNIB, we can help with our • Restricted growth and development telephone Helpline and our Sight Loss Counselling team. Your GP or social worker may also find a Genital abnormalities • counsellor for you if you feel this might help. • Ear abnormalities Your eye clinic may also have an Eye Clinic Liaison The ophthalmologist caring for your child will refer Officer (ECLO), who can be on hand to provide them to a paediatrician to carry out the relevant you with further practical and emotional support tests that will detect whether or not they have any about your child’s or your own eye condition. other general health problems associated with their coloboma, such as CHARGE syndrome.

9 Further help and support You can find more information about all the support available to children and adults with For children who have sight loss as a result of their sight problems on our website rnib.org.uk or coloboma, having the right support at an early age can by calling our Helpline on 0303 123 9999. make a big difference. Your local authority (LA) should have at least one qualified teacher of children and young people with vision impairment (QTVI) to work with you and Sources of support your child both at home and at school. A QTVI is a qualified If you have questions about anything you’ve read teacher who can provide support with development, play, in this factsheet, or just want to speak to someone learning and education. At an early stage, ask your local about this eye condition, please get in touch with us. authority to put you in contact with a QTVI. They will It doesn’t matter if you or your child has just been support you and your child as soon as a diagnosed with coloboma or you’ve known about it is suspected or diagnosed. If you have difficulty getting for a while; we’re here to support you at every step. help, or need the details of the specialist teacher in Our Helpline is your direct line to the support, advice your area, contact RNIB Helpline on 0303 123 9999. and services you need. Whether you want to know Local social services can help people of all ages who more about your eye condition, buy a product from have sight loss to get out and about safely and can our shop, join our library, find out about possible offer practical adaptations around the home. benefit entitlements, or be put in touch with a trained counsellor, we’re only a call away. Depending on how much of a person’s sight is affected by coloboma, they may be eligible to be registered It’s also a way for you to join RNIB Connect, our as sight impaired (partially sighted) or severely sight community for anyone affected by sight loss. RNIB impaired (blind). An ophthalmologist would be able Connect is free to join and you’ll have the chance to to tell you whether you or your child is eligible. meet other people with similar experiences in our Registration can act as a passport to help and sometimes helpful, welcoming and supportive community. to financial concessions, but a lot of this support is still available to people who aren’t registered.

10 Give us a call today to find Other useful organisations out how we can help you. MACS (Microphthalmia, Anophthalmia and Coloboma Support) RNIB Helpline An organisation supporting children born 0303 123 9999 without eyes or with underdeveloped eyes. [email protected] Helpline: 0800 169 8088 We’re ready to answer your call Monday to Friday Email: [email protected] 8am to 8pm and Saturday 9am to 1pm. Web: www.macs.org.uk You can also get in touch by post LOOK UK or by visiting our website: Supports young people (up to age 29) and families of children living with a visual impairment RNIB Helpline: 01432 376314 105 Judd Street Email: [email protected] London WC1H 9NE Web: www.look-uk.org rnib.org.uk Children and Young People’s Services within Guide (formally Blind Children UK) Helpline: 0800 781 1444. Email: [email protected] Web: www.guidedogs.org.uk

11 We value your feedback You can help us improve our information RNIB Helpline by letting us know what you think about it. Is this factsheet useful, easy to read and 0303 123 9999 detailed enough – or could we improve it? Send your comments to us by emailing us at [email protected] [email protected] 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 [email protected]

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Last updated: October 2018 Next review: October 2021

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