{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,27]],"date-time":"2026-02-27T17:34:15Z","timestamp":1772213655446,"version":"3.50.1"},"reference-count":67,"publisher":"BMJ","issue":"9","license":[{"start":{"date-parts":[[2022,9,8]],"date-time":"2022-09-08T00:00:00Z","timestamp":1662595200000},"content-version":"unspecified","delay-in-days":7,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"name":"FCT","award":["PTDC\/DPT-EPI\/0412\/2012"],"award-info":[{"award-number":["PTDC\/DPT-EPI\/0412\/2012"]}]},{"name":"FCT","award":["SFRH\/BD\/119420\/2016"],"award-info":[{"award-number":["SFRH\/BD\/119420\/2016"]}]}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Open"],"accepted":{"date-parts":[[2022,7,6]]},"published-print":{"date-parts":[[2022,9]]},"abstract":"<jats:sec>\n                    <jats:title>Objectives<\/jats:title>\n                    <jats:p>The aim of this study was to estimate the prevalence and causes of vision impairment (VI) in Portugal.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Setting<\/jats:title>\n                    <jats:p>Information about people with VI was obtained from primary care centres, blind association (ACAPO) and from hospitals (the PCVIP study) in the Northwest of Portugal during a period spanning years 2014\u20132015. Causes of VI were obtained from hospitals.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Participants<\/jats:title>\n                    <jats:p>Administrative and medical records of people with visual acuity in the better seeing eye of 0.5 decimal (0.30logMAR) or worse and\/or visual field less than 20\u00b0 were investigated. Capture\u2013recapture with log-linear models was applied to estimate the number of individuals missing from lists of cases obtained from available sources.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Primary and secondary outcome measures<\/jats:title>\n                    <jats:p>Log-linear models were used to estimate the crude prevalence and the category specific prevalence of VI.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Crude prevalence of VI was 1.97% (95% CI 1.56% to 2.54%), and standardised prevalence was 1% (95% CI 0.78% to 1.27%). The age-specific prevalence was 3.27% (95% CI 2.36% to 4.90%), older than 64 years, 0.64% (95% CI 0.49% to 0.88%), aged 25\u201364 years, and 0.07% (95% CI 0.045% to 0.13%), aged less than 25 years. The female-to-male ratio was 1.3, that is, higher prevalence among females. The five leading causes of VI were diabetic retinopathy, cataract, age-related macular degeneration, glaucoma and disorders of the globe.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>The prevalence of VI in Portugal was within the expected range and in line with other European countries. A significant number of cases of VI might be due to preventable cases and, therefore, a reduction of the prevalence of VI in Portugal seems possible. Women and old people were more likely to have VI and, therefore, these groups require extra attention. Future studies are necessary to characterise temporal changes in prevalence of VI in Portugal.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/bmjopen-2021-056995","type":"journal-article","created":{"date-parts":[[2022,9,8]],"date-time":"2022-09-08T11:36:28Z","timestamp":1662636988000},"page":"e056995","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":4,"title":["Cross-sectional study investigating the prevalence and causes of vision impairment in Northwest Portugal using capture\u2013recapture"],"prefix":"10.1136","volume":"12","author":[{"given":"Pedro Lima","family":"Ramos","sequence":"first","affiliation":[{"name":"Department of Medicine and Optometry, Linnaeus University, Kalmar, Sweden"},{"name":"Low Vision and Visual Rehabilitation Lab, Department and Center of Physics - Optometry and Vision Science, University of Minho, Braga, Portugal"}]},{"given":"Rui","family":"Santana","sequence":"additional","affiliation":[{"name":"Escola Nacional Saude Publica, Comprehensive Health Research Centre Universidade Nova de Lisboa, Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8242-7021","authenticated-orcid":false,"given":"Ana Patricia","family":"Marques","sequence":"additional","affiliation":[{"name":"Escola Nacional Saude Publica, Comprehensive Health Research Centre Universidade Nova de Lisboa, Lisboa, Portugal"},{"name":"International Centre for Eye Health, London School of Hygiene and Tropical Medicine, London, UK"}]},{"given":"Ines","family":"Sousa","sequence":"additional","affiliation":[{"name":"Department of Mathematics and Applications and Center of Molecular and Environmental Biology, School of Sciences, University of Minho, Braga, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8374-0298","authenticated-orcid":false,"given":"Amandio","family":"Rocha-Sousa","sequence":"additional","affiliation":[{"name":"Department of Surgery and Physiology, Faculty of Medicine, University of Porto, Porto, Portugal"},{"name":"Department of ophthalmology, Centro Hospitalar e Universit\u00e1rio de S\u00e3o Jo\u00e3o, Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3436-2010","authenticated-orcid":false,"given":"Antonio Filipe","family":"Macedo","sequence":"additional","affiliation":[{"name":"Department of Medicine and Optometry, Linnaeus University, Kalmar, Sweden"},{"name":"Low Vision and Visual Rehabilitation Lab, Department and Center of Physics - Optometry and Vision Science, University of Minho, Braga, Portugal"}]}],"member":"239","published-online":{"date-parts":[[2022,9,8]]},"reference":[{"key":"2025121513385599000_12.9.e056995.1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1755-3768.2008.01191.x"},{"key":"2025121513385599000_12.9.e056995.2","doi-asserted-by":"publisher","DOI":"10.1001\/archopht.120.6.774"},{"key":"2025121513385599000_12.9.e056995.3","doi-asserted-by":"crossref","first-page":"e783","DOI":"10.1111\/aos.13430","article-title":"Visual and health outcomes, measured with the activity inventory and the EQ-5D, in visual impairment","volume":"95","author":"Macedo","year":"2017","journal-title":"Acta Ophthalmol"},{"key":"2025121513385599000_12.9.e056995.4","doi-asserted-by":"crossref","first-page":"1341","DOI":"10.1177\/0269215521997991","article-title":"Is perceived social support more important than visual acuity for clinical depression and anxiety in patients with age-related macular degeneration and diabetic retinopathy?","volume":"35","author":"Hern\u00e1ndez-Moreno","year":"2021","journal-title":"Clin Rehabil"},{"key":"2025121513385599000_12.9.e056995.5","doi-asserted-by":"crossref","first-page":"378","DOI":"10.1080\/09286586.2019.1632904","article-title":"Productivity losses and their explanatory factors amongst people with impaired vision","volume":"26","author":"Marques","year":"2019","journal-title":"Ophthalmic Epidemiol"},{"key":"2025121513385599000_12.9.e056995.6","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pone.0198631","article-title":"The use of informal care by people with vision impairment","volume":"13","author":"Marques","year":"2018","journal-title":"PLoS One"},{"key":"2025121513385599000_12.9.e056995.7","first-page":"289","article-title":"The prevalence of visual impairment in the adult population","volume":"116","author":"Wolfram","year":"2019","journal-title":"Dtsch Arztebl Int"},{"key":"2025121513385599000_12.9.e056995.8","unstructured":"Welp A , Woodbury R . Making eye health a population health imperative: vision for tomorrow surveillance and research. Available: https:\/\/www.ncbi.nlm.nih.gov\/books\/NBK402371\/2016"},{"key":"2025121513385599000_12.9.e056995.9","doi-asserted-by":"crossref","first-page":"e888","DOI":"10.1016\/S2214-109X(17)30293-0","article-title":"Magnitude, temporal trends, and projections of the global prevalence of blindness and distance and near vision impairment: a systematic review and meta-analysis","volume":"5","author":"Bourne","year":"2017","journal-title":"Lancet Glob Health"},{"key":"2025121513385599000_12.9.e056995.10","doi-asserted-by":"crossref","first-page":"53","DOI":"10.3109\/09286586.2015.1066396","article-title":"Danish rural eye study: epidemiology of adult visual impairment","volume":"23","author":"H\u00f8eg","year":"2016","journal-title":"Ophthalmic Epidemiol"},{"key":"2025121513385599000_12.9.e056995.11","doi-asserted-by":"publisher","DOI":"10.1001\/archopht.123.8.1117"},{"key":"2025121513385599000_12.9.e056995.12","doi-asserted-by":"crossref","first-page":"168","DOI":"10.1111\/aos.13542","article-title":"Visual impairment and blindness in Hungary","volume":"96","author":"Szab\u00f3","year":"2018","journal-title":"Acta Ophthalmol"},{"key":"2025121513385599000_12.9.e056995.13","first-page":"484","article-title":"Blindness and visual impairment in Germany: a slight fall in prevalence","volume":"109","author":"Finger","year":"2012","journal-title":"Dtsch Arztebl Int"},{"key":"2025121513385599000_12.9.e056995.14","doi-asserted-by":"publisher","DOI":"10.1038\/sj.eye.6700606"},{"key":"2025121513385599000_12.9.e056995.15","doi-asserted-by":"publisher","DOI":"10.1136\/bmjopen-2015-009006"},{"key":"2025121513385599000_12.9.e056995.16","doi-asserted-by":"publisher","DOI":"10.1136\/bjophthalmol-2011-300908"},{"key":"2025121513385599000_12.9.e056995.17","doi-asserted-by":"publisher","DOI":"10.1167\/iovs.09-3486"},{"key":"2025121513385599000_12.9.e056995.18","doi-asserted-by":"publisher","DOI":"10.1136\/jnnp-2016-314839"},{"key":"2025121513385599000_12.9.e056995.19","doi-asserted-by":"publisher","DOI":"10.1136\/bjophthalmol-2012-302563"},{"key":"2025121513385599000_12.9.e056995.20","doi-asserted-by":"publisher","DOI":"10.1111\/j.1600-0420.2006.00867.x"},{"key":"2025121513385599000_12.9.e056995.21","doi-asserted-by":"publisher","DOI":"10.1080\/14766650252962649"},{"key":"2025121513385599000_12.9.e056995.22","doi-asserted-by":"crossref","first-page":"27","DOI":"10.1046\/j.0742-3071.2001.00603.x","article-title":"What is the prevalence of visual impairment in the general and diabetic populations: are there ethnic and gender differences?","volume":"19","author":"Hayward","year":"2002","journal-title":"Diabet Med"},{"key":"2025121513385599000_12.9.e056995.23","first-page":"1444","article-title":"Measuring and interpreting the incidence of congenital ocular anomalies: lessons from a national study of congenital cataract in the UK","volume":"42","author":"Rahi","year":"2001","journal-title":"Invest Ophthalmol Vis Sci"},{"key":"2025121513385599000_12.9.e056995.24","first-page":"236","article-title":"Capture-recapture analysis of ascertainment by active surveillance in the British congenital cataract study","volume":"40","author":"Rahi","year":"1999","journal-title":"Invest Ophthalmol Vis Sci"},{"key":"2025121513385599000_12.9.e056995.25","doi-asserted-by":"publisher","DOI":"10.1136\/bjo.2004.059915"},{"key":"2025121513385599000_12.9.e056995.26","doi-asserted-by":"crossref","first-page":"201","DOI":"10.1007\/s00347-019-0853-y","article-title":"Epidemiologie hochgradiger Sehbehinderungen und Blindheit \u00e4lterer Menschen in Deutschland","volume":"116","author":"Mauschitz","year":"2019","journal-title":"Der Ophthalmologe"},{"key":"2025121513385599000_12.9.e056995.27","doi-asserted-by":"crossref","first-page":"1354","DOI":"10.1353\/hpu.2010.0939","article-title":"Methodological issues in the collection, analysis, and reporting of granular data in Asian American populations: historical challenges and potential solutions","volume":"21","author":"Islam","year":"2010","journal-title":"J Health Care Poor Underserved"},{"key":"2025121513385599000_12.9.e056995.28","doi-asserted-by":"crossref","first-page":"310","DOI":"10.1080\/09286586.2020.1749286","article-title":"A review of capture-recapture methods and its possibilities in ophthalmology and vision sciences","volume":"27","author":"Ramos","year":"2020","journal-title":"Ophthalmic Epidemiol"},{"key":"2025121513385599000_12.9.e056995.29","unstructured":"Statistics Portugal . Census 2011, 2011. Available: https:\/\/censos.ine.pt\/xportal\/xmain?xpid=CENSOS&xpgid=censos2011_apresentacao"},{"key":"2025121513385599000_12.9.e056995.30","unstructured":"International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10)-WHO Version for 2016, 2016. H54: visual impairment including blindness (binocular or monocular). Available: https:\/\/icd.who.int\/browse10\/2010\/en#\/H54"},{"key":"2025121513385599000_12.9.e056995.31","unstructured":"Rep\u00fablica Dda . Decreto-Lei n.\u00ba 202\/96 Di\u00e1rio da Rep\u00fablica, 1996. Available: https:\/\/dre.pt\/pesquisa\/-\/search\/226809\/details\/maximized"},{"key":"2025121513385599000_12.9.e056995.32","unstructured":"Rep\u00fablica Dda . Decreto-Lei n.\u00ba 352\/2007 Di\u00e1rio da Rep\u00fablica. Available: https:\/\/dre.pt\/application\/file\/a\/629015"},{"key":"2025121513385599000_12.9.e056995.33","doi-asserted-by":"crossref","DOI":"10.1186\/s12886-018-0889-9","article-title":"Predicting participation of people with impaired vision in epidemiological studies","volume":"18","author":"Ramos","year":"2018","journal-title":"BMC Ophthalmol"},{"key":"2025121513385599000_12.9.e056995.34","article-title":"Prevalence of visual impairment in the municipality of Braga -Portugal using capture-recapture methods","volume":"59","author":"Lima Ramos","year":"2018","journal-title":"Invest Ophthalmol Vis Sci"},{"key":"2025121513385599000_12.9.e056995.35","article-title":"Capture-recapture: a method for determining the prevalence of vision impaiment in the population","volume":"45","author":"Gordon","year":"2017","journal-title":"Clin Experiment Ophthalmol"},{"key":"2025121513385599000_12.9.e056995.36","doi-asserted-by":"publisher","DOI":"10.1126\/science.240.4855.991"},{"key":"2025121513385599000_12.9.e056995.37","doi-asserted-by":"publisher","DOI":"10.1093\/ije\/25.3.474"},{"key":"2025121513385599000_12.9.e056995.38","doi-asserted-by":"publisher","DOI":"10.1002\/sim.996"},{"key":"2025121513385599000_12.9.e056995.39","unstructured":"Rivest L-P , Baillargeon S . Package \u2018Rcapture\u2019 v1.4-3. CRANR-Projectorg, 2019. Available: https:\/\/CRAN.R-project.org\/package=Rcapture"},{"key":"2025121513385599000_12.9.e056995.40","doi-asserted-by":"crossref","DOI":"10.18637\/jss.v019.i05","article-title":"Rcapture: Loglinear models for capture-recapture in R","volume":"19","author":"Baillargeon","year":"2007","journal-title":"J Stat Softw"},{"key":"2025121513385599000_12.9.e056995.41","unstructured":"A A . Chapter 9: Loglinear Models for Contingency Tables. In: Categorical data analysis. 3rd ed. John Wiley and Sons, 2013."},{"key":"2025121513385599000_12.9.e056995.42","doi-asserted-by":"crossref","first-page":"95","DOI":"10.1146\/annurev-statistics-031017-100641","article-title":"Multiple systems estimation (or capture-recapture estimation) to inform public policy","volume":"5","author":"Bird","year":"2018","journal-title":"Annu Rev Stat Appl"},{"key":"2025121513385599000_12.9.e056995.43","doi-asserted-by":"crossref","first-page":"408","DOI":"10.1016\/j.ophtha.2013.07.017","article-title":"Visual impairment and blindness in Spanish adults: geographic inequalities are not explained by age or education","volume":"121","author":"Rius","year":"2014","journal-title":"Ophthalmology"},{"key":"2025121513385599000_12.9.e056995.44","doi-asserted-by":"publisher","DOI":"10.1016\/j.ophtha.2003.05.010"},{"key":"2025121513385599000_12.9.e056995.45","doi-asserted-by":"crossref","first-page":"1089","DOI":"10.1007\/s00417-020-04885-4","article-title":"Markedly decreasing incidence of cause-specific blindness in Saxony (eastern Germany)","volume":"259","author":"Claessen","year":"2021","journal-title":"Graefes Arch Clin Exp Ophthalmol"},{"key":"2025121513385599000_12.9.e056995.46","doi-asserted-by":"crossref","first-page":"2473","DOI":"10.1016\/j.ophtha.2015.08.004","article-title":"First incidence and progression study for diabetic retinopathy in Portugal, the RETINODIAB study: evaluation of the screening program for Lisbon region","volume":"122","author":"Dutra Medeiros","year":"2015","journal-title":"Ophthalmology"},{"key":"2025121513385599000_12.9.e056995.47","doi-asserted-by":"publisher","DOI":"10.1016\/j.pcd.2016.05.003"},{"key":"2025121513385599000_12.9.e056995.48","unstructured":"Sa\u00fade D-Gda . Norma n.016\/2018. Available: https:\/\/normas.dgs.min-saude.pt\/2018\/09\/13\/rastreio-da-retinopatia-diabetica\/2018 https:\/\/normas.dgs.min-saude.pt\/2018\/09\/13\/rastreio-da-retinopatia-diabetica\/"},{"key":"2025121513385599000_12.9.e056995.49","doi-asserted-by":"crossref","first-page":"1149","DOI":"10.1016\/j.ophtha.2018.02.005","article-title":"The decreasing prevalence of Nonrefractive visual impairment in older Europeans: a meta-analysis of published and unpublished data","volume":"125","author":"Delcourt","year":"2018","journal-title":"Ophthalmology"},{"key":"2025121513385599000_12.9.e056995.50","doi-asserted-by":"crossref","first-page":"119","DOI":"10.1159\/000371584","article-title":"Prevalence of age-related macular degeneration in Portugal: the coimbra eye study - Report 1","volume":"233","author":"Cachulo","year":"2015","journal-title":"Ophthalmologica"},{"key":"2025121513385599000_12.9.e056995.51","doi-asserted-by":"publisher","DOI":"10.1038\/eye.2009.32"},{"key":"2025121513385599000_12.9.e056995.52","doi-asserted-by":"publisher","DOI":"10.1038\/sj.eye.6702837"},{"key":"2025121513385599000_12.9.e056995.53","doi-asserted-by":"publisher","DOI":"10.1136\/bjophthalmol-2013-303578"},{"key":"2025121513385599000_12.9.e056995.54","doi-asserted-by":"publisher","DOI":"10.1016\/j.ajo.2008.11.021"},{"key":"2025121513385599000_12.9.e056995.55","doi-asserted-by":"publisher","DOI":"10.1016\/j.ophtha.2013.05.025"},{"key":"2025121513385599000_12.9.e056995.56","doi-asserted-by":"crossref","first-page":"661","DOI":"10.1093\/eurpub\/cky245","article-title":"Why are there gender inequalities in visual impairment?","volume":"29","author":"Rius Ulldemolins","year":"2019","journal-title":"Eur J Public Health"},{"key":"2025121513385599000_12.9.e056995.57","doi-asserted-by":"publisher","DOI":"10.1136\/bjo.86.7.716"},{"key":"2025121513385599000_12.9.e056995.58","doi-asserted-by":"publisher","DOI":"10.1016\/S0161-6420(02)01898-5"},{"key":"2025121513385599000_12.9.e056995.59","doi-asserted-by":"crossref","first-page":"e505","DOI":"10.1097\/MD.0000000000000505","article-title":"The prevalence and causes of visual impairment and blindness among older adults in the city of Lodz, Poland","volume":"94","author":"Nowak","year":"2015","journal-title":"Medicine"},{"key":"2025121513385599000_12.9.e056995.60","doi-asserted-by":"crossref","first-page":"519","DOI":"10.1007\/s10654-012-9705-7","article-title":"Evidence for a considerable decrease in total and cause-specific incidences of blindness in Germany","volume":"27","author":"Claessen","year":"2012","journal-title":"Eur J Epidemiol"},{"key":"2025121513385599000_12.9.e056995.61","doi-asserted-by":"publisher","DOI":"10.1136\/bmjopen-2016-015024"},{"key":"2025121513385599000_12.9.e056995.62","doi-asserted-by":"crossref","first-page":"521","DOI":"10.1007\/s00592-021-01687-w","article-title":"The contribution of the English NHS diabetic eye screening programme to reductions in diabetes-related blindness, comparisons within Europe, and future challenges","volume":"58","author":"Scanlon","year":"2021","journal-title":"Acta Diabetol"},{"key":"2025121513385599000_12.9.e056995.63","doi-asserted-by":"publisher","DOI":"10.1038\/sj.eye.6701879"},{"key":"2025121513385599000_12.9.e056995.64","doi-asserted-by":"crossref","first-page":"e000076","DOI":"10.1136\/bmjophth-2017-000076","article-title":"Monocular and binocular visual impairment in the UK Biobank study: prevalence, associations and diagnoses","volume":"3","author":"McKibbin","year":"2018","journal-title":"BMJ Open Ophthalmol"},{"key":"2025121513385599000_12.9.e056995.65","unstructured":"Vaz de Sousa A . Gest\u00e3o de listas de espera para a cirurgia eletiva: O caso Portugu\u00eas, 2018."},{"key":"2025121513385599000_12.9.e056995.66","doi-asserted-by":"crossref","first-page":"350","DOI":"10.1111\/opo.12665","article-title":"Cost-effectiveness of basic vision rehabilitation (the basic VRS-effect study): study protocol for a randomised controlled trial","volume":"40","author":"Hern\u00e1ndez-Moreno","year":"2020","journal-title":"Ophthalmic Physiol Opt"},{"key":"2025121513385599000_12.9.e056995.67","doi-asserted-by":"publisher","DOI":"10.1136\/bjo.86.7.795"}],"container-title":["BMJ Open"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/syndication.highwire.org\/content\/doi\/10.1136\/bmjopen-2021-056995","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,12,15]],"date-time":"2025-12-15T21:39:06Z","timestamp":1765834746000},"score":1,"resource":{"primary":{"URL":"https:\/\/bmjopen.bmj.com\/lookup\/doi\/10.1136\/bmjopen-2021-056995"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,9]]},"references-count":67,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2022,9,8]]},"published-print":{"date-parts":[[2022,9]]}},"alternative-id":["10.1136\/bmjopen-2021-056995"],"URL":"https:\/\/doi.org\/10.1136\/bmjopen-2021-056995","relation":{"has-preprint":[{"id-type":"doi","id":"10.1101\/2021.07.06.21260069","asserted-by":"object"}]},"ISSN":["2044-6055","2044-6055"],"issn-type":[{"value":"2044-6055","type":"print"},{"value":"2044-6055","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,9]]}}}