{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T04:50:56Z","timestamp":1787028656837,"version":"build-2736575974"},"reference-count":41,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2025,4,24]],"date-time":"2025-04-24T00:00:00Z","timestamp":1745452800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JCM"],"abstract":"<jats:p>Background\/Objectives: Keratoconus is a progressive corneal disorder that significantly impairs visual quality and daily functioning. This study aimed to translate, culturally adapt, and validate the Polish version of the Keratoconus Outcomes Research Questionnaire (KORQ), a tool designed to assess keratoconus-related vision problems and their impact on quality of life. Methods: This study involved three phases: translation, validation, and optimization. The translation followed cross-cultural adaptation guidelines, including forward translation, back translation, and pretesting. In the validation phase, 100 patients with keratoconus completed the Polish KORQ. Psychometric properties were assessed using Rasch analysis to evaluate item fit, reliability, unidimensionality, and targeting. Exploratory and confirmatory factor analyses (EFA and CFA) were conducted to examine the latent structure of the questionnaire. Regression analysis examined the demographic and clinical factors influencing keratoconus severity and vision-related quality of life, with the total KORQ score as the dependent variable. Results: The Polish KORQ demonstrated excellent psychometric properties. Internal consistency was high (\u03b1 = 0.95 for activity limitation, \u03b1 = 0.87 for symptoms). Rasch analysis confirmed good item fit and measurement reliability. EFA identified a two-factor structure consistent with the original questionnaire, explaining 53% of the total variance. CFA supported this model, with good fit indices (CFI = 0.981, TLI = 0.980), despite slightly elevated RMSEA (0.104) and SRMR (0.109). The two latent factors were moderately correlated (r = 0.729). Regression analysis showed that uncorrected visual acuity and disease severity significantly predicted lower quality of life. Conclusions: The Polish KORQ is a reliable and valid tool for assessing the impact of keratoconus in clinical and research settings.<\/jats:p>","DOI":"10.3390\/jcm14092959","type":"journal-article","created":{"date-parts":[[2025,4,24]],"date-time":"2025-04-24T11:44:52Z","timestamp":1745495092000},"page":"2959","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Validation of the Polish Version of the Keratoconus Outcomes Research Questionnaire: Tool for Vision-Related Quality of Life in Patients with Keratoconus"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4386-1217","authenticated-orcid":false,"given":"Magdalena","family":"Nandzik","sequence":"first","affiliation":[{"name":"Department of Ophthalmology, Faculty of Medical Sciences, Zabrze Medical University of Silesia, 40-760 Katowice, Poland"},{"name":"Department of Ophthalmology, District Railway Hospital in Katowice, Medical University of Silesia, Panewnicka 65, 40-760 Katowice, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7295-4936","authenticated-orcid":false,"given":"Adam","family":"Wyl\u0119ga\u0142a","sequence":"additional","affiliation":[{"name":"Department of Ophthalmology, Faculty of Medical Sciences, Zabrze Medical University of Silesia, 40-760 Katowice, Poland"},{"name":"Department of Ophthalmology, District Railway Hospital in Katowice, Medical University of Silesia, Panewnicka 65, 40-760 Katowice, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0267-7835","authenticated-orcid":false,"given":"Magdalena","family":"Kijonka","sequence":"additional","affiliation":[{"name":"Department of Ophthalmology, Faculty of Medical Sciences, Zabrze Medical University of Silesia, 40-760 Katowice, Poland"},{"name":"Department of Ophthalmology, District Railway Hospital in Katowice, Medical University of Silesia, Panewnicka 65, 40-760 Katowice, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8120-7801","authenticated-orcid":false,"given":"Dominika","family":"Szkodny","sequence":"additional","affiliation":[{"name":"Department of Ophthalmology, Faculty of Medical Sciences, Zabrze Medical University of Silesia, 40-760 Katowice, Poland"},{"name":"Department of Ophthalmology, District Railway Hospital in Katowice, Medical University of Silesia, Panewnicka 65, 40-760 Katowice, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5733-5923","authenticated-orcid":false,"given":"Bart\u0142omiej","family":"Markuszewski","sequence":"additional","affiliation":[{"name":"Department of Ophthalmology, District Railway Hospital in Katowice, Medical University of Silesia, Panewnicka 65, 40-760 Katowice, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6707-5790","authenticated-orcid":false,"given":"Edward","family":"Wyl\u0119ga\u0142a","sequence":"additional","affiliation":[{"name":"Department of Ophthalmology, Faculty of Medical Sciences, Zabrze Medical University of Silesia, 40-760 Katowice, Poland"},{"name":"Department of Ophthalmology, District Railway Hospital in Katowice, Medical University of Silesia, Panewnicka 65, 40-760 Katowice, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,4,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"527","DOI":"10.1016\/j.ajo.2004.04.031","article-title":"Quality of life in keratoconus","volume":"138","author":"Kymes","year":"2004","journal-title":"Am. J. Ophthalmol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"573","DOI":"10.1097\/ICO.0000000000003119","article-title":"Patient-reported outcomes in keratoconus: A Save Sight Keratoconus Registry study","volume":"42","author":"Kandel","year":"2023","journal-title":"Cornea"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"111234","DOI":"10.3389\/fmed.2023.1212314","article-title":"Management of keratoconus: An updated review","volume":"10","author":"Deshmukh","year":"2023","journal-title":"Front. Med."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"380","DOI":"10.1097\/ICO.0000000000002170","article-title":"Measurement of quality of life in keratoconus","volume":"39","author":"Kandel","year":"2020","journal-title":"Cornea"},{"key":"ref_5","first-page":"212","article-title":"Polish adaptation and validation of the Visual Function Questionnaire (VFQ-25) in multiple sclerosis patients","volume":"63","author":"Brola","year":"2010","journal-title":"Wiad. Lek."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"395","DOI":"10.1097\/OPX.0000000000001035","article-title":"Development of a keratoconus-specific questionnaire using Rasch analysis","volume":"94","author":"Khadka","year":"2017","journal-title":"Optom. Vis. Sci."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"211","DOI":"10.1097\/ICO.0000000000003506","article-title":"Evaluation of the German version of the Keratoconus Outcomes Research Questionnaire","volume":"43","author":"Pomberger","year":"2024","journal-title":"Cornea"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"3026","DOI":"10.1177\/11206721211028044","article-title":"The Italian version of the Keratoconus Outcomes Research Questionnaire (KORQ): Translation and validation of psychometric properties","volume":"31","author":"Ferrini","year":"2021","journal-title":"Eur. J. Ophthalmol."},{"key":"ref_9","first-page":"589","article-title":"Translation and validation of the \u201cQuestionnaire for research on keratoconus results\u201d (KORQ) in the Colombian population","volume":"95","author":"Balparda","year":"2020","journal-title":"Arch. Soc. Esp. Oftalmol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"450","DOI":"10.5935\/0004-2749.20210067","article-title":"Translation and validation of the Portuguese version of the Keratoconus Outcomes Research Questionnaire (KORQ)","volume":"84","author":"Pinto","year":"2021","journal-title":"Arq. Bras. Oftalmol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"101725","DOI":"10.1016\/j.clae.2022.101746","article-title":"Impact of corneal collagen cross-linking on vision-related quality of life measured with the Keratoconus Outcomes Research Questionnaire (KORQ) in patients with keratoconus","volume":"46","author":"Ferrini","year":"2023","journal-title":"Contact Lens Anterior Eye"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1410","DOI":"10.1097\/ICO.0000000000003185","article-title":"Cross-linking improves the quality of life of people with keratoconus: A cross-sectional and longitudinal study from the Save Sight Keratoconus Registry","volume":"42","author":"Kandel","year":"2023","journal-title":"Cornea"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"297","DOI":"10.1007\/BF02310555","article-title":"Coefficient alpha and the internal structure of tests","volume":"16","author":"Cronbach","year":"1951","journal-title":"Psychometrika"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"93","DOI":"10.1177\/014662168701100107","article-title":"Statistical inference for coefficient alpha","volume":"11","author":"Feldt","year":"1987","journal-title":"Appl. Psychol. Meas."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"561","DOI":"10.1007\/BF02293814","article-title":"A rating formulation for ordered response categories","volume":"43","author":"Andrich","year":"1978","journal-title":"Psychometrika"},{"key":"ref_16","unstructured":"Bond, T.G., and Fox, C.M. (2007). Applying the Rasch Model: Fundamental Measurement in the Human Sciences, Lawrence Erlbaum Associates. [2nd ed.]."},{"key":"ref_17","first-page":"84","article-title":"Computation of outfit and infit statistics","volume":"3","author":"Wright","year":"1990","journal-title":"Rasch Meas. Trans."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"189","DOI":"10.1891\/jnum.10.3.189.52562","article-title":"An introduction to Rasch measurement for scale development and person assessment","volume":"10","author":"Smith","year":"2002","journal-title":"J. Nurs. Meas."},{"key":"ref_19","unstructured":"Smith, E.V., and Smith, R.M. (2004). Introduction to Rasch Measurement: Theory, Models and Applications, JAM Press. [1st ed.]."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Wind, S.A., and Hua, C. (2022). Rasch Measurement Theory Analysis in R, Taylor & Francis.","DOI":"10.1201\/9781003174660"},{"key":"ref_21","unstructured":"R Core Team (2024). R: A Language and Environment for Statistical Computing, R Foundation for Statistical Computing. Available online: https:\/\/www.r-project.org."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1","DOI":"10.18637\/jss.v048.i06","article-title":"Mirt: A multidimensional item response theory package for the R environment","volume":"48","author":"Chalmers","year":"2012","journal-title":"J. Stat. Softw."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1","DOI":"10.18637\/jss.v020.i09","article-title":"Extended Rasch modeling: The eRm package for the application of IRT models in R","volume":"20","author":"Mair","year":"2007","journal-title":"J. Stat. Softw."},{"key":"ref_24","unstructured":"Makowski, D., Ben-Shachar, M.S., Patil, I., and L\u00fcdecke, D. (2024, December 05). Automated Results Reporting as a Practical Tool to Improve Reproducibility and Methodological Best Practices Adoption. CRAN; 2023. Available online: https:\/\/cran.r-project.org\/web\/packages\/report\/index.html."},{"key":"ref_25","unstructured":"Sarkar, D. (2024, December 05). Lattice: Multivariate Data Visualization with R. R Package Version 0.22-5. Available online: https:\/\/CRAN.R-project.org\/package=lattice."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"570","DOI":"10.32614\/RJ-2021-053","article-title":"Reproducible summary tables with the gtsummary package","volume":"13","author":"Sjoberg","year":"2021","journal-title":"R. J."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1","DOI":"10.18637\/jss.v021.i12","article-title":"Reshaping data with the reshape package","volume":"21","author":"Wickham","year":"2007","journal-title":"J. Stat. Softw."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Wickham, H. (2016). Ggplot2: Elegant Graphics for Data Analysis, Springer. [2nd ed.]. Available online: https:\/\/ggplot2.tidyverse.org.","DOI":"10.1007\/978-3-319-24277-4_9"},{"key":"ref_29","unstructured":"Wickham, H., Fran\u00e7ois, R., Henry, L., and M\u00fcller, K. (2024, December 05). Dplyr: A Grammar of Data Manipulation. R Package Version 1.1.4. Available online: https:\/\/CRAN.R-project.org\/package=dplyr."},{"key":"ref_30","unstructured":"Revelle, W. (2024, December 05). Psych: Procedures for Psychological, Psychometric, and Personality Research. R Package Version 2.4.6. Available online: https:\/\/CRAN.R-project.org\/package=psych."},{"key":"ref_31","unstructured":"Zhu, H. (2024, December 05). KableExtra: Construct Complex Tables with Knitr. R Package Version 1.3.4. Available online: https:\/\/CRAN.R-project.org\/package=kableExtra."},{"key":"ref_32","unstructured":"Xie, Y. (2024, December 05). Knitr: A General-Purpose Package for Dynamic Report Generation in R. R Package Version 1.46. Available online: https:\/\/yihui.org\/knitr\/."},{"key":"ref_33","unstructured":"Kline, R.B. (2016). Principles and Practice of Structural Equation Modeling, The Guilford Press. [4th ed.]."},{"key":"ref_34","unstructured":"Bollen, K.A., and Long, J.S. (1993). Alternative ways of assessing model fit. Testing Structural Equation Models, Sage."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Nandzik, M., Wyl\u0119ga\u0142a, A., Szkodny, D., Wr\u00f3blewska-Czajka, E., Wyl\u0119ga\u0142a, E., and Orzechowska-Wyl\u0119ga\u0142a, B. (2024). Risk factors for glaucoma and ocular hypertension and post-transplant complications in keratoconus: A multivariable analysis. J. Clin. Med., 13.","DOI":"10.3390\/jcm13185407"},{"key":"ref_36","first-page":"957","article-title":"The Keratoconus Outcome Research Questionnaire: A cross-cultural validation study of the Danish version","volume":"39","author":"Groenborg","year":"2020","journal-title":"Cornea"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1417","DOI":"10.1016\/0895-4356(93)90142-N","article-title":"Cross-cultural adaptation of health-related quality of life measures: Literature review and proposed guidelines","volume":"46","author":"Guillemin","year":"1993","journal-title":"J. Clin. Epidemiol."},{"key":"ref_38","first-page":"361","article-title":"Quality of life of a sample of people with keratoconus in KSA","volume":"18","author":"Alatawi","year":"2023","journal-title":"J. Taibah Univ. Med. Sci."},{"key":"ref_39","first-page":"257","article-title":"Asymmetry in keratoconus and vision-related quality of life","volume":"32","author":"Walline","year":"2013","journal-title":"Cornea"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"1043","DOI":"10.1007\/s11136-015-1117-1","article-title":"The influence of the refractive correction on vision-related quality of life in keratoconus patients","volume":"25","author":"Perez","year":"2016","journal-title":"Qual. Life Res."},{"key":"ref_41","first-page":"694542","article-title":"Vision-related quality of life in patients with keratoconus","volume":"2014","author":"Altun","year":"2014","journal-title":"J. Ophthalmol."}],"container-title":["Journal of Clinical Medicine"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2077-0383\/14\/9\/2959\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T17:21:06Z","timestamp":1760030466000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2077-0383\/14\/9\/2959"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,4,24]]},"references-count":41,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2025,5]]}},"alternative-id":["jcm14092959"],"URL":"https:\/\/doi.org\/10.3390\/jcm14092959","relation":{},"ISSN":["2077-0383"],"issn-type":[{"value":"2077-0383","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,4,24]]}}}