{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,3]],"date-time":"2026-10-03T08:40:22Z","timestamp":1791016822430,"version":"4.1.0"},"reference-count":25,"publisher":"Public Library of Science (PLoS)","issue":"4","license":[{"start":{"date-parts":[[2026,4,24]],"date-time":"2026-04-24T00:00:00Z","timestamp":1776988800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"<jats:sec id=\"sec001\">\n                    <jats:title>Purpose<\/jats:title>\n                    <jats:p>Although regional disparities in access to surgical care have been reported across medical specialties, nationwide evaluations of variation in ophthalmic surgical services remain limited. This study examined prefecture-level differences in major ophthalmic surgeries in Japan using publicly available claims data.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec002\">\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>We analyzed the ninth release of the National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB Open Data) for fiscal year 2022 (April 2022\u2013March 2023). Prefecture-level procedure counts were extracted for cataract surgery (K282), vitrectomy (K279\u2013K281 and related codes), glaucoma surgery (relevant K-codes), and corneal transplantation. To reduce potential underestimation in non\u2013Diagnosis Procedure Combination settings, ophthalmology-related procedures reimbursed under the Short-Stay Surgery Basic Fee 3 (A400) were identified and incorporated according to predefined mapping rules. Surgical rates per 100,000 population and per board-certified ophthalmologist were calculated. Regional inequality was quantified using population-weighted Gini coefficients. Associations between ophthalmologist density and surgical volume were assessed using Pearson\u2019s correlation coefficients.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec003\">\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Nationwide totals were 1,777,502 cataract surgeries, 154,336 vitrectomies, 80,753 glaucoma surgeries, and 2,895 corneal transplantations. Prefecture-level surgical rates per 100,000 population varied 1.8-fold for cataract surgery, 3.3-fold for vitrectomy, and 7.8-fold for glaucoma surgery. Several prefectures reported no corneal transplantation cases. Population-weighted Gini coefficients were 0.064 for cataract surgery, 0.125 for vitrectomy, 0.190 for glaucoma surgery, and 0.351 for corneal transplantation. Similar patterns were observed after adjusting for age structure, indicating that regional disparities were not solely explained by demographic differences. Ophthalmologist density varied 2.5-fold across prefectures and was positively correlated with surgical volume for cataract surgery and vitrectomy, but not for glaucoma surgery.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec004\">\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Using nationwide claims data, we identified substantial regional variation in major ophthalmic surgical procedures in Japan, with greater inequality observed for more specialized surgeries. These findings provide a population-level description of ophthalmic surgical distribution and may inform future evaluations of healthcare resource allocation.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1371\/journal.pone.0347587","type":"journal-article","created":{"date-parts":[[2026,4,24]],"date-time":"2026-04-24T17:40:20Z","timestamp":1777052420000},"page":"e0347587","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":1,"title":["Disparity of ophthalmic surgeries in Japan"],"prefix":"10.1371","volume":"21","author":[{"given":"Teruna","family":"Shiga","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ayane","family":"Tanaka","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yoshiko","family":"Fukuda","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8506-8503","authenticated-orcid":true,"given":"Kenji","family":"Kashiwagi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2026,4,24]]},"reference":[{"key":"pone.0347587.ref001","doi-asserted-by":"crossref","first-page":"183","DOI":"10.1007\/s10384-021-00898-6","article-title":"Recent trends in glaucoma surgery: a nationwide database study in Japan, 2011-2019","volume":"66","author":"A Fujita","year":"2022","journal-title":"Jpn J Ophthalmol"},{"key":"pone.0347587.ref002","article-title":"Trends in ophthalmic surgery among older patients in Japan (fiscal years 2018 to 2022): A national claims database study on surgical shifts and the COVID-19 pandemic\u2019s impact","volume":"17","author":"Y Kabata","year":"2025","journal-title":"Cureus"},{"issue":"7","key":"pone.0347587.ref003","doi-asserted-by":"crossref","first-page":"1047","DOI":"10.3390\/jpm13071047","article-title":"Nationwide Analysis of Glaucoma Surgeries in Fiscal Years of 2014 and 2020 in Japan","volume":"13","author":"M Tanito","year":"2023","journal-title":"J Pers Med"},{"key":"pone.0347587.ref004","doi-asserted-by":"crossref","first-page":"22884","DOI":"10.1038\/s41598-023-49705-x","article-title":"Annual trends of ophthalmic surgeries in Japan\u2019s super-aged society, 2014-2020: a national claims database study","volume":"13","author":"S Wada","year":"2023","journal-title":"Scientific Reports"},{"issue":"8","key":"pone.0347587.ref005","doi-asserted-by":"crossref","first-page":"1583","DOI":"10.1038\/s41433-022-02181-5","article-title":"Ophthalmic surgery in New Zealand: analysis of 410,099 surgical procedures and nationwide surgical intervention rates from 2009 to 2018","volume":"37","author":"RR Hossain","year":"2023","journal-title":"Eye (Lond)"},{"issue":"1","key":"pone.0347587.ref006","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1620\/tjem.251.1","article-title":"Physician Distribution by Specialty and Practice Setting: Findings in Japan in 2000, 2010 and 2016","volume":"251","author":"R Ikesu","year":"2020","journal-title":"Tohoku J Exp Med"},{"issue":"2","key":"pone.0347587.ref007","first-page":"7163","article-title":"Geographic distribution of family physicians in Japan and the USA: a cross-sectional comparative study","volume":"22","author":"Y Okazaki","year":"2022","journal-title":"Rural Remote Health"},{"issue":"9","key":"pone.0347587.ref008","doi-asserted-by":"crossref","first-page":"784","DOI":"10.1136\/bjo.80.9.784","article-title":"Geographical variations in rates of ophthalmic surgery","volume":"80","author":"HS Jones","year":"1996","journal-title":"Br J Ophthalmol"},{"issue":"2","key":"pone.0347587.ref009","doi-asserted-by":"crossref","first-page":"117","DOI":"10.1001\/jamaophthalmol.2024.5605","article-title":"Geographic Distribution of US Ophthalmic Surgical Subspecialists","volume":"143","author":"A Ahmed","year":"2025","journal-title":"JAMA Ophthalmol"},{"issue":"1","key":"pone.0347587.ref010","doi-asserted-by":"crossref","first-page":"119","DOI":"10.1016\/j.ophtha.2024.07.032","article-title":"Geographic Access to Eye Care in the United States","volume":"132","author":"JJ Franco","year":"2025","journal-title":"Ophthalmology"},{"key":"pone.0347587.ref011","unstructured":"Ministry of Health LaWJ National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB) Open Data. 2022."},{"key":"pone.0347587.ref012","unstructured":"Ministry of Health LaWJ Population Estimates as of October 1, 2024. 2024."},{"key":"pone.0347587.ref013","unstructured":"Society JO board-certified ophthalmologist Search (Ophthalmology)."},{"key":"pone.0347587.ref014","unstructured":"Ministry of Health LaWM National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB) Open Data. 2022."},{"key":"pone.0347587.ref015","unstructured":"Ministry of Health LaWM National Health and Nutrition Survey (Kokuho & Kenko Ch\u014dsa) 2024. 2025."},{"issue":"4","key":"pone.0347587.ref016","doi-asserted-by":"crossref","first-page":"453","DOI":"10.1111\/ceo.13430","article-title":"Longitudinal changes in global cataract surgery rate inequality and associations with socioeconomic indices","volume":"47","author":"W Yan","year":"2019","journal-title":"Clin Exp Ophthalmol"},{"issue":"6","key":"pone.0347587.ref017","doi-asserted-by":"crossref","first-page":"707","DOI":"10.1097\/OPX.0000000000000590","article-title":"Distribution of cataract surgical rate and its economic inequality in Iran","volume":"92","author":"H Hashemi","year":"2015","journal-title":"Optom Vis Sci"},{"issue":"7","key":"pone.0347587.ref018","doi-asserted-by":"crossref","first-page":"664","DOI":"10.26719\/2018.24.7.664","article-title":"Geographical inequality in cataract surgery among Iranians between 2006 and 2011","volume":"24","author":"C Alinia","year":"2018","journal-title":"East Mediterr Health J"},{"issue":"11","key":"pone.0347587.ref019","doi-asserted-by":"crossref","first-page":"2081","DOI":"10.1016\/j.ophtha.2014.05.013","article-title":"Global prevalence of glaucoma and projections of glaucoma burden through 2040: a systematic review and meta-analysis","volume":"121","author":"Y-C Tham","year":"2014","journal-title":"Ophthalmology"},{"issue":"12","key":"pone.0347587.ref020","doi-asserted-by":"crossref","first-page":"1382","DOI":"10.1016\/j.ophtha.2025.07.011","article-title":"Geographic Distribution of Access to Glaucoma Surgery: An IRIS\u00ae Registry (Intelligent Research in Sight) Analysis","volume":"132","author":"A Lokhande","year":"2025","journal-title":"Ophthalmology"},{"issue":"3","key":"pone.0347587.ref021","doi-asserted-by":"crossref","first-page":"587","DOI":"10.1007\/s00417-019-04484-y","article-title":"Socioeconomic disparities in the global burden of glaucoma: an analysis of trends from 1990 to 2016","volume":"258","author":"J Wu","year":"2020","journal-title":"Graefes Arch Clin Exp Ophthalmol"},{"key":"pone.0347587.ref022","doi-asserted-by":"crossref","first-page":"167","DOI":"10.1001\/jamaophthalmol.2015.4776","volume":"134","author":"P Gain","year":"2016","journal-title":"JAMA Ophthalmol"},{"issue":"3","key":"pone.0347587.ref023","doi-asserted-by":"crossref","first-page":"590","DOI":"10.1016\/j.ophtha.2015.11.001","article-title":"Rates of Vitrectomy among Enrollees in a United States Managed Care Network, 2001-2012","volume":"123","author":"TJ Wubben","year":"2016","journal-title":"Ophthalmology"},{"key":"pone.0347587.ref024","first-page":"24741264251358073","article-title":"Temporal Trends and Regional Variations in Retinal Detachment Repair Procedures in the United States","author":"F Montazeri","year":"2025","journal-title":"J Vitreoretin Dis"},{"key":"pone.0347587.ref025","doi-asserted-by":"crossref","first-page":"608","DOI":"10.1007\/s10384-021-00849-1","article-title":"Trends in surgical procedures and indications for corneal transplantation over 27 years in a tertiary hospital in Japan","volume":"65","author":"A Takahashi","year":"2021","journal-title":"Japanese Journal of Ophthalmology"}],"container-title":["PLOS One"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0347587","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,24]],"date-time":"2026-04-24T17:40:27Z","timestamp":1777052427000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0347587"}},"subtitle":[],"editor":[{"given":"Shinji","family":"Kakihara","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"editor"}]}],"short-title":[],"issued":{"date-parts":[[2026,4,24]]},"references-count":25,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2026,4,24]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pone.0347587","relation":{},"ISSN":["1932-6203"],"issn-type":[{"value":"1932-6203","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,4,24]]}}}