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Temporal trends in the epidemiology of childhood severe visual impairment and blindness in the UK
  1. Lucinda J Teoh1,2,
  2. Ameenat Lola Solebo1,2,3,4,5,
  3. Jugnoo S Rahi1,2,3,4,5
  4. on behalf of the British Childhood Visual Impairment and Blindness Study Interest Group
    1. 1Population, Policy and Practice, UCL Great Ormond Street Institute of Child Health, London, UK
    2. 2Ulverscroft Vision Research Group, UCL Great Ormond Street Institute of Child Health, London, UK
    3. 3Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
    4. 4Moorfields NIHR Biomedical Research Centre, London, UK
    5. 5UCL Institute of Ophthalmology, London, UK
    1. Correspondence to Professor Jugnoo S Rahi, Population Policy and Practice, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK; j.rahi{at}ucl.ac.uk

    Abstract

    Background/aims Understanding temporal trends in childhood visual disability is necessary for planning and evaluating clinical services and health policies. We investigate the changing epidemiology of severe visual impairment (SVI) and blindness (BL) in children in the UK in the 21st century.

    Methods Comparative analysis of two national population-based epidemiological studies of incident childhood SVI/BL (ICD-10 definition; visual acuity worse than 1.0 LogMAR in the better eye). We carry out comparative analysis of studies conducted in 2000 and 2015 using identical methods.

    Results Overall annual and cumulative incidence rates remained broadly stable in 2015 at 0.38 per 10 000 (95% CI 0.34 to 0.41) for 0–15 years old and 5.65 per 10 000 (5.16 to 6.18) by 16 years, respectively, and with annual incidence in infancy (3.52 per 10 000, 3.13 to 3.97) remaining considerably higher than any other age. Mortality among children diagnosed in infancy declined (from 61.4 to 25.6 per 1000), despite an increase (from 77% to 84%, p=0.037) in the overall proportion with significant non-ophthalmic impairments/disorders. The relative contribution of all the main groups of disorders increased over time, most notably cerebral visual impairment (from 50% to 61%). Aetiological factors operating prenatally continued to predominate, with an increased relative contribution of hereditary conditions in all children (from 35% to 57%, p<0.001). The substantially elevated rates for any ethnic minority group and those born preterm were unchanged, with amplification of increased rates associated with low birth weight.

    Conclusion The changing landscape of healthcare and increased survival of affected children, is reflected in increasing clinical complexity and heterogeneity of all-cause SVI/BL alongside declining mortality.

    • child health (paediatrics)
    • epidemiology
    • public health

    Data availability statement

    No data are available. Deidentified individual participant data will not be made available as ethics and governance approvals do not allow this.

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    Data availability statement

    No data are available. Deidentified individual participant data will not be made available as ethics and governance approvals do not allow this.

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    Footnotes

    • Twitter @Rahi_Eye_Vision

    • Collaborators British Childhood Visual Impairment and Blindness Study Interest Group: Joe Abbott (Birmingham Children's Hospital, Steelhouse Lane,Birmingham, B4 6NH, England); Wajda Abdullah (Sheffield Children's Hospital, Western Bank, S10 2TH); Gill Adams (Moorfields Eye Hospital, City Road, EC1V 2PD); Louise Allen (Addenbrookes Hospital, Mills Road, Cambridge CB2 0QQ); Christopher Anderson (Salisbury District Hospital); Karen Ansell (East Surrey Hospital); Samira Anwar (Leicester Royal Infirmary); Isabel Ash (Nottingham University Hospital, B Floor, East Block, Queens Medical Centre, NG7 2UH); Jane Ashworth (Manchester Royal Eye Hospital, Oxford Road, M13 9WL); Sher Aslam (Oxford Eye Hospital); Majunath Astagi (Cumbria Partnership NHS Foundation Trust, Atkinson Health Centre, Barrow-in-Furness); Colin Ball (Kings College Hospital); Rajesh Balu (University Hospital of Durham); Victoria Barrett (Sussex Eye Hospital); Zahabiyah Bassi (Alder Hey Children's NHS Foundation Trust, Eaton Road, Liverpool, L12 2AP, England); Adam Bates (Maidstone Hospital); Dushyant Batra (Nottingham City Hospital); Sarah Bell (Wexham Park Hospital); Linda Belmour (Moorfields Eye Hospital, City Road, EC1V 2PD); James Benzimra (Royal Devon and Exeter Hospital, Barrack Road, EX2 5DW); Ginny Birrell (The James Cook University Hospital (Middlesborough)); Susmito Biswas (Manchester Royal Eye Hospital, Oxford Road, M13 9WL); Andrew Blaikie (Queen Margaret Hospital NHS Trust); Michael Blundell (Alexandra House, Les Frieteaux, St Martin's, Guernsey, GY1 3EX); Kate Bolton (Queen Alexandra Hospital, Portsmouth); Ewoud Bos (Flintshire Children's centre Mancot Clinic (Liverpool)); Pamela Bowen (WWL EYE Unit Boston house Frog Lane Wigan WN6 7LB); Richard Bowman (Great Ormond Street Children's Hospital, Great Ormond Street, WC1N 3JH); Natalie Boyle (Queen Margaret Hospital NHS Trust); John Bradbury (Bradford Royal Infirmary, Duckworth Lane, BD8 7RJ); Maria Bredow (Community Child Health Bristol); Marsel Bregu (Warrington Hospital NHS Trust); Nicholas Brennan (St Richard's Hospital (Western Sussex Hospitals)); Rosie Brennan (Altnagelvin Area Hospital); Paul Brittain (Sussex Eye Hospital); Charles Buchanan (Kings College Hospital); Catey Bunce (Moorfields Eye Hospital, City Road, EClV 2PD); Howard Bunting (Queen Mary's Hospital, Sidcup); Priscilla Burgess (Great Western Hospital, Swindon); Cathie Burke (Sunderland Eye Infirmary, Queen Alexandra Road, Sunderland SR2 9HP); Alexandra Kate Bush (Southampton General Hospital, Tremona road, Southampton, SO16 6YD); Jeremy Butcher (Countess of Chester Hospital FT); Lucilla Butler (The Birmingham and Midland Eye Centre City Hospital, Sandwell and West Birmingham Hospitals NHS Trust, Dudley Road Birmingham B18 7QU); Clare Cane (Barnet Hospital); Cathryn Chadwick (Northampton General Hospital); Ruth Charlton (Epsom Hospital); Anne-Marie Childs (Leeds General Infirmary); Jessy Choi (Sheffield Children's Hospital, Western Bank, S10 2TH); Vivi Choleva (Bristol Eye Hospital, Lower Maudlin Street, BS1 2LX); Amanda Churchill (Bristol Eye Hospital, Lower Maudlin Street, BS1 2LX); Michael Clarke (Royal Victoria Infirmary, Queen Victoria Road, NE1 4LP); Peter Clayton (Royal Manchester Children's Hospital); Luke Clifford (Royal Hampshire County Hospital); Alan Connor (Royal Victoria Infirmary, Queen Victoria Road, NE1 4LP); Rachel Cox (Bristol Royal Hospital for Children); Lyn Cresswell (NHS Lothian Edinburgh, Department of Community Child, Health 10 Chalmers Crescent Edinburgh EH9 1TS); Annegret Dahlmann-Noor (Moorfields Eye Hospital, City Road, EClV 2PD); Angela D'Amore (Rosie Maternity Hospital (Cambridge)); Mehul Dattani (Great Ormond Street Children's Hospital, Great Ormond Street, WC1N 3JH); Fiona Dean (Coventry & Warwickshire NHS Trust); Anita Devlin (Royal Victoria Infirmary); Luna Dhir (Chelsea and Westminister Hospital); Cora Doherty (University Hospital of Wales); Suzanne Dorey (Alexandra House, Guernsey); Fiona Drimmie (Tayside Children's Hospital (Dundee) (Ninewells)); Tina Duke (Royal Gwent Hospital, Newport); Gordon Dutton (Glasgow Caledonian University, Glasgow G4 0BA); Fiona Eaton (University Hospitals of Morecombe Bay (Lancashire)); Megan Eaton (Yeovil District Hospital); Danielle Eckersley (Whipps Cross Hospital, Whipps Cross Road, E11 1NR); Clive Edelsten Great (Ormond Street Children's Hospital, Great Ormond Street, WC1N 3JH); Rachel Elderkin (Royal Devon & Exeter Hospital); Julia Ennis (Sheffield Children's Hospital, Western Bank, S10 2TH); Julia Escardo-Paton (Royal Gwent Hospital); Ziad Estephen (Calderdale Royal Hospital); Onajite Etuwewe (Scunthorpe General Hospital); Anthony Evans (Queen Alexandra Hospital, PORTSMOUTH, PO3 5LY); Adjoa Ezekwe (Greenwich Community Health Services (London)); Jenny Fairfield (Altnagelvin Area Hospital); Kevin Falzon (York Hospital NHS Trust, Wigginton Road, York, North Yorkshire YO31 8HE); Allison Ferguson (Glenfarg Child Development Centre); Brian Fleck (Princess Alexandra Eye Pavilion, Edinburgh (NHS Lothian); Mary Gainsborough (North Bristol NHS Trust, Osprey Court, Hawkfield Business Park, Whitchurch Lane, BS14 0BB); Alexandra Galloway (Queen Elizabeth II Hospital (Welwyn garden city)); Naomi Gerson-Sofer (Oxleas NHS Foundation Trust, Community Paediatrics Bungalow 1 Wensley Close Eltham London SE9 5AB, Naomi.gerson-sofer@oxleas.nhs.uk); Caspar Gibbon (North Devon District Hospital); Patricia Gibson (The Princess Royal Hospital- Telford); Kevin Goss (Leeds General Infirmary); Katherine Graham-Evans (Queen Alexandra Hospital (Portsmouth)); Judith Gray (Alder Hey Children's NHS Foundation Trust, Eaton Road, Liverpool, L12 2AP, England); Anna Gregory (Leeds, St James's University Hospital); Arun Gulati (St Mary's Hospital-Isle of Wight); Deniz Gurtin-Zorkun (Homerton Hospital); Emma Guy (Leeds General Infirmary); Diab Haddad (St Peter's Hospital (Surrey)); Helen Haggerty (Royal Victoria Infirmary, Queen Victoria Road, NE1 4LP); Paul Haigh (University Hospital Of North Staffordshire NHS Trust); Julia Hale (Wellington Way Health Centre (London)); Samer Hamada (Queen Victoria Hospital - West Sussex); Joanne Hancox (Moorfields Eye Hospital, City Road, EClV 2PD); Kerry Hanna (Univeristy of Liverpoool); Sian Harris (Royal Cornwall Hospital); Christine Harrison (Rotherham District General Hospital); Phillip Harvey (Queens Hospital NHS Trust (Burton-on-Trent)); Sophie Headland (Royal Cornwall Hospital, Treliske, Cornwall TR1 3LJ); Dominic Heath (Sussex Eye Hospital); Paul Heaton (Yeovil District Hospital); Robert Henderson (Great Ormond Street Children's Hospital, Great Ormond Street, WC1N 3JH); Melanie Hingorani (Hinchingbrooke Hospital/ Moorfields Eye Hospital); Zoe Hirst (Leeds Teaching Hospital Trust); Claire Hogg (Royal Brompton Hospital); Wolfgang Hogler (Birmingham Children's Hospital); Roger Holden (Derby Royal Hospital); Janice Hoole (Leeds Teaching Hospital Trust); Karen Horridge (Sunderland Royal Hospital); Delyth Howard (Poole Hospital NHS Foundation Trust); Rachel Howells (Royal Devon & Exeter Hospital); Vanessa Irvine (St Richard's Hospital); Clare Irving (Borders General Hospital); Nicola Johnson (Musgrove Park Hospital (Taunton)); Ian Johnston (Croydon Health Services NHS Trust); Alice Jollands (Ninewells Hospital & Medical School (Dundee)); David Jones (Royal Cornwall Hospital, Treliske, Cornwall TR1 3LJ); Annie Joseph (North Staffordshire University Hospital, Hartshill Road, ST4 7PA); Archana Joshi (Luton & Dunstable Hospital); Pugazhvendan Kandaswamy (Nevill Hall Hospital); Charles Kattakayam (Ashton Health Centre (Preston)); Joseph Keenan (Royal Surrey County Hospital); Anne Kelly (Darlington Memorial Hospital, County Durham (new address)); James Kersey (Royal Bournemouth Hospital); Awais Khan (Ipswich Hospital); Peng Khaw (Moorfields Eye Hospital, City Road, EClV 2PD); Tina Kipioti (Birmingham Heartlands Hospital); Sadia Kiran (Westhampnett Centre (Chichester)); Lesley Kneen (Royal Shrewsbury Hospitals NHS Trust); Ajay Kotagiri (Sunderland Eye Infirmary); Richa Kulshrestha (Robert Jones and Agnes Hunt Orthapaedric Hospital); Rosemary Lambley (Nottingham University Hospital, B Floor, East Block, Queens Medical Centre, NG7 2UH); Tim Lavy (Falkirk Community Hospital Westburn Avenue Falkirk, FK1 5QE); Joanna Lawson (Barnet General Hospital); Vicki Lee (Sheffield Children's Hospital); Jane Leitch (Epsom & St Helier University Trust); Julie Lennon (Manchester Royal Eye Hospital, Oxford Road, M13 9WL); Gabi Lipshen (Bolton Foundation NHS Trust, Halliwell Health & Children's Centre); Chris Lloyd (Great Ormond Street Children's Hospital, Great Ormond Street, WC1N 3JH); John Loftus (Hackney Ark); Tom Lomas (Warrington General Hospital, Lovely Lane, Warrington, WA5 1QG); Vernon Long (Leeds, St James' University Hospital, Beckett Street, LS9 7TF); Jane Mackinnon (Raigmore Hospital, Inverness (NHS Highland)); Mary MacRae (Princess Alexandra Eye Pavilion, Edinburgh (NHS Lothian)); Usman Mahmood (Hull Royal Infirmary, Anlaby Road, HU3 2KZ); Anna Maino (Manchester Royal Eye Hospital, Oxford Road, M13 9WL); Sarah Maling (Stoke Mandeville Hospital); David Mansfield (Inverclyde Royal Hospital); Elizabeth Marder (Nottingham University Hospital, B Floor, East Block, Queens Medical Centre, NG7 2UH); Richard Markham (Bristol Eye Hospital, Lower Maudlin Street, BS1 2LX); Jane Marr (Sheffield Children's Hospital, Western Bank, S10 2TH); Catherine Marsh (Royal Bournemouth Hospital Castle Lane East Bournemouth BH7 7DW); Anna Maw (Addenbrooke's Hospital); Eleanor McCartney (Pendragon House (Royal Cornwall Hospital)); Helen McCullagh (Leeds General Infirmary); Anna McDonald (Ipswich Hospital); Derek McPhee (Alder Hey Children's NHS Foundation Trust, Eaton Road, Liverpool, L12 2AP, England); Lawrence Miall (Leeds General Infirmary); Shila Mistry (Leicester Community Children's Service); Benjamin Moate (Furness General Hospital (Uni Hosp of Morecombe Bay)); Meyyammai Mohan (East Lancashire Healthcare NHS Trust Royal Blackburn Hospital Haslingden Road Blackburn BB2 3HH); Helen Moore (Chesterfield Royal Hospital); Will Moore (Great Ormond Street Children's Hospital, Great Ormond Street, WC1N 3JH); Nicola Morgan (Royal Gwent Hospital); Claire Morton (Abergele Hospital); Alan Mulvihill (Princess Alexandra Eye Pavilion, Edinburgh (NHS Lothian); Ranjit Nair (Worcester Royal Hospital Charles Hastings Way Worcester WR5 1 DD); Bill Newman (Manchester Royal Eye Hospital, Oxford Road, M13 9WL); Christiane Nitsch (Kaleidoscope Centre - Lewisham); Katy O'Connell (Cheltenham General Hospital, Sandford Road, Gloucestershire GL54 7AN); Ngozi Oluonye (Great Ormond Street Children's Hospital, Great Ormond Street, WC1N 3JH); Vittaldas Pai (Pinderfields Hospital (Wakefield)); Helen Palmer (QE Hospital Gateshead); Maria Papadopoulos (Moorfields Eye Hospital, City Road, EClV 2PD); Shelagh Parkinson (Dr Gray's Hospital NHS Grampian); Bina Parmar (Milton Keynes Hospital NHS Trust); Manoj Parulekar (Birmingham Children's Hospital, Steelhouse Lane, Birmingham, B4 6NH, England); Madhavi Parvathareddy (Southmead General Hospital (North Bristol)); Dipesh Patel (Moorfields Eye Hospital, City Road, EC1V 2PD); Himanshu Patel (Moorfields Eye Hospital, City Road, EC1V 2PD); Kamal Patel (Royal Alexandra Children's Hospital - Brighton); Philippa Pennefather (Arrowe Park Hospital, Upton, L49 5PE); Flaudia Petrone (Stoke Mandeville Hospital); Marcus Pierrepoint (Nevill Hall Hospital); Rachel Pilling (Bradford Royal Infirmary, Duckworth Lane, BD8 7RJ); Sally Pollard (Bradford Royal Infirmary, Duckworth Lane, BD8 7RJ); Renata Puertas (Moorfields Eye Hospital, City Road, EC1V 2PD); Karen Pysden (Leeds General Infirmary); Anthony Quinn (Royal Devon and Exeter Hospital, Barrack Road, EX2 5DW); Philip Quinn (Craigavon Area Hospital (Amargh)); Diyaa Rachdan (Nottingham University Hospital, B Floor, East Block, Queens Medical Centre, NG7 2UH); Jyoti Raina (North Middlesex Hospital); Saul Rajak (Sussex Eye Hospital); Laura Ramm (Birmingham Children's Hospital, Steelhouse Lane, Birmingham, B4 6NH, England); Catherine Rands (Cambridgeshire Community Services Oak Tree Centre Huntingdon PE29 7HN); Tekki Rao (Luton & Dunstable Hospital); Mary Ray (Royal Alexandra Hospital - Paisley); Ashwin Reddy (Barts Health NHS Trust, Whitechapel Road, London E1 1BB); Sheilla Reilly (East Lancashire Healthcare NHS Trust Royal Blackburn Hospital Haslingden Road Blackburn BB2 3HH); Maralla Rekha (Newton Heath Health Centre (Manchester)); Greg Richardson (Barts Health NHS Trust, Whitechapel London E1 1BB); Andrew Riordan (Alder Hey Children's Hospital); Nerys Roberts (Chelsea & Westminster Hospital); Helen Robertson (Birmingham Community NHS Trust); Gillian Robinson (St George's Centre Leeds); Neil Rogers (Sheffield Teaching Hospitals Trust- Royal Hallamshire Hospital); Shakir Saeed (Ysbyty Gwynedd, Bangor); Caroline Salmon (Royal Surrey County Hospital); Jenefer Sargent (Great Ormond Street Children's Hospital, Great Ormond Street, WC1N 3JH); Nagini Sarvananthan (Leicester Royal Infirmary, Infirmary Square, LE1 5WW); Conrad Schmoll (Princess Alexandra Eye Pavilion, Edinburgh (NHS Lothian)); James Self (Southampton General Hospital, Tremona road, Southampton, SO16 6YD.); P Sellar (West Cumberland Hospital); Elaine Service (Royal Lancaster Infirmary); Ayad Shafiq (Royal Victoria Infirmary, Queen Victoria Road, NE1 4LP); Shilpa Shah (Craigavon Area Hospital (Amargh)); Vinod Sharma (Manchester Royal Eye Hospital, Oxford Road, M13 9WL); Jemima Sharp (Wythenshawe Hospital - Manchester); Julia Shaw (North Hampshire Hospital); Manjula Shenoy (Manor Hospital, Walsall); Tamsin Sleep (Torbay Hospital (Torbay & South Devon FT)); Elisa Smit (University Hospital of Wales); Katherine Smyth (Bolton Hospital NHS Trust); Lynne Speedwell (Great Ormond Street Children's Hospital, Great Ormond Street, WC1N 3JH); Katherine Spowart (Glenfarg Child Development Centre); P Standring (Princess Elizabeth Hospital St Martins Guernsey); Paulo Stanga (Manchester Royal Eye Hospital, Oxford Road, M13 9WL); Alison Stanley (Worcester Acute Care NHS Trust); Alan Stanton (Solihull Care Trust (Heart of England); David Steel (Sunderland Eye Infirmary, Queen Alexandra Road, Sunderland SR2 9HP); John Stephen (Borders General Hospital); Catherine Stewart (Princess Alexander Hospital Harlow, Hamstel Road CM20 1QX); Jessica Street (Forth Valley Royal Hospital (Falkirk)); Sally Stucke (Ross Road Clinic and Child Development Centre); Shona Sutherland (Queen Margaret Hospital NHS Trust- Victoria Hospital); Katya Tambe (Nottingham University Hospital, B Floor, East Block, Queens Medical Centre, NG7 2UH); Anamika Tandon (Sheffield Children's Hospital, Western Bank, S10 2TH); Alison Tappin (Queen Alexandra Hospital, Portsmouth); Kate Taylor (Royal Victoria Infirmary, Queen Victoria Road, NE1 4LP); Robert Taylor (York Hospital NHS Trust, Wigginton Road, York, North Yorkshire YO31 8HE); Katherine Teasdale (Sheffield Children's Hospital); Maria Theodorou (Moorfields Eye Hospital, City Road, EClV 2PD); Gareth Thomas (Morriston Hospital); Megan Thomas (Blenheim House Child Development and Family Support Centre Whitegate (Health Centre Whitegate Drive Blackpool FY3 9ES); Paula Thomas (Great Ormond Street Children's Hospital, Great Ormond Street, WC1N 3JH); Dorothy Thompson (Great Ormond Street Children's Hospital, Great Ormond Street, WC1N 3JH); Stephen Thomson (Raigmore Hospital, NHS Highland); Indrajit Thopte (The York Hospital); Peter Tiffin (Sunderland Eye Infirmary, Queen Alexandra Road, Sunderland SR2 9HP); Angela Tillett (Colchester Hospital (University)); Heidi Traunecker (Llandough Hospital); Maria Tsimpida (Barts Health NHS Trust, Whitechapel Road, London E1 1BB); Vivienne Van Someren (Royal Free Hospital, London); Udupa Venkatesh (Scarborough General Hospital); Zoe Vermaak (Queen Mary's Hospital for Children (Epsom & St Helier)); Michael Vincent (Wansbeck Hospital North Tyneside General); David Walker (Nottingham University Hospital, B Floor, East Block, Queens Medical Centre, NG7 2UH); Simon Walker (Leighton Hospital, Middlewich Road, CW1 4QJ); Deidre Walsh (Coleraine (Causeway) Hospital (Londonderry)); Bronwyn Walters (Great Ormond Street Children's Hospital, Great Ormond Street, WC1N 3JH); Martin Ward (Platt Royal Victoria Infirmary - Newcastle Upon Tyne); Louise Watson (Upton Hospital); Patrick Watts (University Hospital of Wales, Cardiff Eye Unit, Heath Park, CF4 4XW); Siobhan West (Royal Manchester Children's Hospital); Stephanie West (Southampton General Hospital, Tremona road, Southampton, SO16 6YD); Cathy White (Dept of Child Health, Morriston Hospital, ABM UHB, Abertawe, SA6 6NL); Joy White (Sussex Eye Hospital, Eastern Road, Brighton BN2 5BF); Gabriel Whitlingum (Royal Hampshire County Hospital); Cathy Williams (Bristol Eye Hospital, Lower Maudlin Street, BS1 2LX); Sophie Wilne (Queen's Medical Centre - Nottingham); Janice Wilson (Glasgow Caledonian University, Glasgow G4 0BA); Chien Wong (Great Ormond Street Children's Hospital, Great Ormond Street, WC1N 3JH); Tamsin Woodbridge (Southmead General Hospital (North Bristol)); Paul Wright (East Surrey Hospital); Martha Wyles (Royal Hampshire County Hospital); Philip Wylie (Dorset County Hospital).

    • Contributors JSR is guarantor, conceptualised the study and contributed to study design, data analysis, interpretation, drafting and revision. ALS contributed to study design, data acquisition, data analysis, interpretation, drafting and revision. LJT contributed to data acquisition, data analysis, interpretation, drafting and revision. All authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.

    • Funding This work was funded directly by a Fight for Sight grant (1525/26) and was supported by funding from the Ulverscroft Foundation for the Ulverscroft Vision Research Group. ALS and JSR are supported by the National Institute for Health Research (NIHR) Biomedical Research Centres at Moorfields Eye Hospital/University College London Institute of Ophthalmology. JSR is a National Institute for Health Research (NIHR) Senior Investigator. All research at Great Ormond Street Hospital NHS Foundation Trust and University College London Great Ormond Street Institute of Child Health is made possible by the NIHR Great Ormond Street Hospital Biomedical Research Centre.

    • Disclaimer The views expressed are those of the author(s) and not necessarily those of the UK National Health Service, the NIHR or the Department of Health.

    • Competing interests None declared.

    • Provenance and peer review Not commissioned; externally peer reviewed.

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