{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,16]],"date-time":"2026-06-16T12:57:00Z","timestamp":1781614620401,"version":"3.54.5"},"reference-count":12,"publisher":"BMJ","issue":"6","content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Case Rep"],"accepted":{"date-parts":[[2026,5,29]]},"published-print":{"date-parts":[[2026,6]]},"abstract":"<jats:p>A patient in their early 40s presented with a bilateral gradual painless decrease in vision. Best-corrected visual acuity (BCVA) was 20\/40p OD and 20\/20 OS. Tomography using Pentacam (OCULUS) demonstrated a bilateral claw-like appearance on keratometry maps with inferior peripheral thinning, suggestive of pellucid marginal corneal degeneration (PMCD). Given the patient\u2019s age is more typical for PMCD and the crab-claw pattern, a diagnosis of PMCD was made. Vision and tomography were stable over 2 years. At year 3, OD developed Vogt\u2019s striae and Fleischer\u2019s ring with tomography showing increased inferior steepening and loss of the characteristic vertical \u2018flat\u2019 band between inferior lobes; BCVA was 20\/50 OD and 20\/20p in OS. The diagnosis was revised to inferior keratoconus (KC) OD and epithelium-off collagen cross-linking (CXL). Progressive inferior KC can present in the fifth decade of life, and a case of early inferior KC at this age is likely to get misdiagnosed as PMCD due to the crab-claw appearance.<\/jats:p>","DOI":"10.1136\/bcr-2025-269951","type":"journal-article","created":{"date-parts":[[2026,6,16]],"date-time":"2026-06-16T12:15:12Z","timestamp":1781612112000},"page":"e269951","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Progressive inferior keratoconus in a patient misdiagnosed as pellucid marginal corneal degeneration"],"prefix":"10.1136","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0009-0006-1917-4598","authenticated-orcid":false,"given":"Rohini","family":"Sonar","sequence":"first","affiliation":[{"name":"Centre for Ocular Regeneration (CORE), Prof. Brien Holden Eye Research Centre (BHERC), LV Prasad Eye Institute, Hyderabad, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9614-951X","authenticated-orcid":false,"given":"Rashmi","family":"Deshmukh","sequence":"additional","affiliation":[{"name":"Shantilal Shanghvi Cornea Institute, LV Prasad Eye Institute, Hyderabad, LV Prasad Eye Institute, Hyderabad, Telangana, India"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2026,6,16]]},"reference":[{"key":"2026061605150694000_19.6.e269951.1","doi-asserted-by":"crossref","first-page":"325","DOI":"10.1097\/ICO.0000000000001169","article-title":"Pellucid marginal degeneration vs inferior keratoconus: why it matters","volume":"46","author":"Belin","year":"2020","journal-title":"J Cataract Refract Surg"},{"key":"2026061605150694000_19.6.e269951.2","doi-asserted-by":"publisher","DOI":"10.1016\/j.ajo.2007.02.032"},{"key":"2026061605150694000_19.6.e269951.3","first-page":"575","article-title":"Evolving Trends in the Diagnosis and Management of Keratoconus Over 3 Decades","volume":"44","author":"Deshmukh","year":"2024","journal-title":"Cornea"},{"key":"2026061605150694000_19.6.e269951.4","doi-asserted-by":"crossref","first-page":"341","DOI":"10.1016\/j.clae.2018.11.010","article-title":"Pellucid marginal degeneration: Detection, discrimination from other corneal ectatic disorders and progression","volume":"42","author":"Mart\u00ednez-Abad","year":"2019","journal-title":"Cont Lens Anterior Eye"},{"key":"2026061605150694000_19.6.e269951.5","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1038\/eye.2017.198","article-title":"Crab claw pattern on corneal topography: pellucid marginal degeneration or inferior keratoconus?","volume":"32","author":"Koc","year":"2018","journal-title":"Eye (Lond)"},{"key":"2026061605150694000_19.6.e269951.6","doi-asserted-by":"publisher","DOI":"10.1001\/archopht.1984.01040030715026"},{"key":"2026061605150694000_19.6.e269951.7","doi-asserted-by":"publisher","DOI":"10.3109\/09286589609080117"},{"key":"2026061605150694000_19.6.e269951.8","doi-asserted-by":"crossref","first-page":"65","DOI":"10.1016\/j.oftal.2022.09.006","article-title":"Clinical-epidemiological characteristics of keratoconus in Asturias","volume":"98","author":"Fern\u00e1ndez Berdasco","year":"2023","journal-title":"Arch Soc Esp Oftalmol (Engl Ed)"},{"key":"2026061605150694000_19.6.e269951.9","doi-asserted-by":"crossref","first-page":"3488","DOI":"10.4103\/ijo.IJO_553_21","article-title":"Clinical profile and demographic distribution of pellucid marginal corneal degeneration in India: A study of 559 patients","volume":"69","author":"Das","year":"2021","journal-title":"Indian J Ophthalmol"},{"key":"2026061605150694000_19.6.e269951.10","doi-asserted-by":"crossref","unstructured":"Sinjab MM , Youssef LN . Pellucid-like keratoconus. F1000Res 2012;1. doi:10.12688\/F1000RESEARCH.1-48.V1\/DOI","DOI":"10.12688\/f1000research.1-48.v1"},{"key":"2026061605150694000_19.6.e269951.11","doi-asserted-by":"publisher","DOI":"10.1136\/bjophthalmol-2020-316496"},{"key":"2026061605150694000_19.6.e269951.12","doi-asserted-by":"crossref","first-page":"101792","DOI":"10.1016\/j.clae.2022.101792","article-title":"Progressive keratoconus in patients older than 48 years","volume":"46","author":"Kollros","year":"2023","journal-title":"Cont Lens Anterior Eye"}],"container-title":["BMJ Case Reports"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/syndication.highwire.org\/content\/doi\/10.1136\/bcr-2025-269951","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,6,16]],"date-time":"2026-06-16T12:15:16Z","timestamp":1781612116000},"score":1,"resource":{"primary":{"URL":"https:\/\/casereports.bmj.com\/lookup\/doi\/10.1136\/bcr-2025-269951"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,6]]},"references-count":12,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2026,6,16]]},"published-print":{"date-parts":[[2026,6]]}},"alternative-id":["10.1136\/bcr-2025-269951"],"URL":"https:\/\/doi.org\/10.1136\/bcr-2025-269951","relation":{},"ISSN":["1757-790X"],"issn-type":[{"value":"1757-790X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,6]]}}}