{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,16]],"date-time":"2026-06-16T23:56:46Z","timestamp":1781654206879,"version":"3.54.5"},"reference-count":9,"publisher":"F1000 Research Ltd","license":[{"start":{"date-parts":[[2012,11,15]],"date-time":"2012-11-15T00:00:00Z","timestamp":1352937600000},"content-version":"unspecified","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":["f1000research.com"],"crossmark-restriction":false},"short-container-title":["F1000Res"],"abstract":"\n Purpose:<\/ns4:bold>\n To study the tomographic features of pellucid-like keratoconus (PLK), and to report a new sign on the pachymetry map (PM) in pellucid marginal degeneration (PMD).\n <\/ns4:p>\n \n Patients and methods:<\/ns4:bold>\n A retrospective descriptive case series was performed in Damascus University in 2011. Clinical and tomographic findings of 15 eyes (9 patients) that had the claw pattern of the anterior sagital map (ASM) were reviewed. Patients were distributed into two groups: (1) 4 eyes were considered PMD since they had inferior corneal thinning on both slitlamp biomicroscopy and PM; (2) 11 eyes were considered as PLK since they did not show inferior corneal thinning. Patients were studied using slitlamp biomicroscopy and Scheimpflug-based tomography (Pentacam HR). The ASM, anterior elevation map (AEM) and PM were analyzed and compared to study the \u201ckissing birds\u201d sign, the \u201cbell\u201d sign, and cone location.\n <\/ns4:p>\n \n Results:<\/ns4:bold>\n Patients\u2019 average age was 25.93\u00b18.05 (16\u201344 years). In total, 60% of patients were male. In group 1, the AEM in the best fit sphere (BFS) mode revealed no kissing birds sign, and the cone was central in 1 eye (25%) and paracentral in 3 eyes (75%). PM showed the bell sign in 4 eyes (100%). In group 2, the AEM in the BFS mode revealed the kissing birds sign in 2 eyes (18.2%), and the cone was central in 1 eye (9.1%), paracentral in 8 eyes (72.7%) and peripheral in 2 eyes (18.2%). PM didn\u2019t show the bell sign in any eye.\n <\/ns4:p>\n \n Conclusion:<\/ns4:bold>\n The claw pattern on the ASM is not a hallmark of PMD; it can be seen in PLK. Cone location does not relate to diagnosis. The \u201cbell\u201d sign on the PM is a deferential diagnostic sign in PMD.\n <\/ns4:p>","DOI":"10.12688\/f1000research.1-48.v1","type":"journal-article","created":{"date-parts":[[2013,5,9]],"date-time":"2013-05-09T12:23:43Z","timestamp":1368102223000},"page":"48","update-policy":"https:\/\/doi.org\/10.12688\/f1000research.crossmark-policy","source":"Crossref","is-referenced-by-count":9,"title":["Case Report: Pellucid-like keratoconus"],"prefix":"10.12688","volume":"1","author":[{"given":"Mazen M","family":"Sinjab","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lara N","family":"Youssef","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"2560","published-online":{"date-parts":[[2012,11,15]]},"reference":[{"key":"ref-1","doi-asserted-by":"publisher","first-page":"297-319","DOI":"10.1016\/S0039-6257(97)00119-7","article-title":"Keratoconus.","volume":"42","author":"Y Rabinowitz","year":"1998","journal-title":"Surv Ophthalmol."},{"key":"ref-2","doi-asserted-by":"publisher","first-page":"393-9","DOI":"10.1038\/sj.eye.6700643","article-title":"Superior pellucid marginal corneal degeneration.","volume":"18","author":"M Sridhar","year":"2004","journal-title":"Eye (Lond)."},{"key":"ref-3","doi-asserted-by":"crossref","first-page":"519-24","DOI":"10.1016\/S0161-6420(87)33416-5","article-title":"Corneal topography of pellucid marginal degeneration.","volume":"94","author":"L Maguire","year":"1987","journal-title":"Ophthalmology."},{"key":"ref-4","first-page":"154-6","article-title":"Ectatic disorders associated with a claw-shaped pattern on corneal topography.","volume":"144","author":"B Lee","year":"2007","journal-title":"Am J Ophthalmol."},{"key":"ref-5","doi-asserted-by":"publisher","first-page":"451-455","DOI":"10.1038\/eye.1996.99","article-title":"Topographic analysis in pellucid marginal corneal degeneration and keratoglobus.","volume":"10","author":"C Karabatsas","year":"1996","journal-title":"Eye (Lond)."},{"key":"ref-6","doi-asserted-by":"publisher","first-page":"1102-1107","DOI":"10.1016\/j.ophtha.2003.09.035","article-title":"Pellucid marginal corneal degeneration.","volume":"111","author":"M Sridhar","year":"2004","journal-title":"Ophthalmology."},{"key":"ref-7","first-page":"11-12","article-title":"Detecting Forme Fruste Keratoconus With the Pentacam.","author":"J Holladay","year":"2008"},{"key":"ref-8","doi-asserted-by":"publisher","first-page":"927-8","DOI":"10.1136\/bjo.80.10.927-a","article-title":"Unilateral pellucid marginal degeneration in an elderly patient.","volume":"80","author":"B Wagenhorst","year":"1996","journal-title":"Br J Ophthalmol."},{"key":"ref-9","doi-asserted-by":"publisher","first-page":"895-6","DOI":"10.1001\/archopht.1984.01040030715026","article-title":"Keratoconus with pellucid marginal corneal degeneration.","volume":"102","author":"F Kayazawa","year":"1984","journal-title":"Arch Ophthalmol."}],"container-title":["F1000Research"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/f1000research.com\/articles\/1-48\/v1\/xml","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/f1000research.com\/articles\/1-48\/v1\/pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/f1000research.com\/articles\/1-48\/v1\/iparadigms","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2018,11,30]],"date-time":"2018-11-30T07:30:30Z","timestamp":1543563030000},"score":1,"resource":{"primary":{"URL":"https:\/\/f1000research.com\/articles\/1-48\/v1"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2012,11,15]]},"references-count":9,"URL":"https:\/\/doi.org\/10.12688\/f1000research.1-48.v1","relation":{"has-review":[{"id-type":"doi","id":"10.5256\/f1000research.217.r379","asserted-by":"subject"},{"id-type":"doi","id":"10.5256\/f1000research.217.r377","asserted-by":"subject"},{"id-type":"doi","id":"10.5256\/f1000research.217.r378","asserted-by":"subject"},{"id-type":"doi","id":"10.5256\/f1000research.217.r377","asserted-by":"object"},{"id-type":"doi","id":"10.5256\/f1000research.217.r379","asserted-by":"object"},{"id-type":"doi","id":"10.5256\/f1000research.217.r378","asserted-by":"object"}]},"ISSN":["2046-1402"],"issn-type":[{"value":"2046-1402","type":"electronic"}],"subject":[],"published":{"date-parts":[[2012,11,15]]},"assertion":[{"value":"Indexed","URL":"https:\/\/f1000research.com\/articles\/1-48\/v1#article-reports","order":0,"name":"referee-status","label":"Referee status","group":{"name":"current-referee-status","label":"Current Referee Status"}},{"value":"10.5256\/f1000research.217.r377, Virender Sangwan, L V Prasad Eye Institute, Kallam Anji Reddy Campus, Hyderabad. Andhra Pradesh, India, 19 Nov 2012, version 1, indexed","URL":"https:\/\/f1000research.com\/articles\/1-48\/v1#referee-response-377","order":0,"name":"referee-response-377","label":"Referee Report","group":{"name":"article-reports","label":"Article Reports"}},{"value":"Mazen Sinjab<\/b>; \nPosted: 19 Nov 2012<\/i>; Thank you Virender for your endorsement.","URL":"https:\/\/f1000research.com\/articles\/1-48\/v1#referee-comment-80","order":1,"name":"referee-comment-80","label":"Referee Comment","group":{"name":"article-reports","label":"Article Reports"}},{"value":"10.5256\/f1000research.217.r378, Michael W Belin, Department of Ophthalmology, University of Arizona, Tucson, AZ, USA, 26 Nov 2012, version 1, indexed","URL":"https:\/\/f1000research.com\/articles\/1-48\/v1#referee-response-378","order":2,"name":"referee-response-378","label":"Referee Report","group":{"name":"article-reports","label":"Article Reports"}},{"value":"Mazen Sinjab<\/b>; \nPosted: 12 Dec 2012<\/i>; Dear Prof Belin, Thank you so much for your valuable comments.Before I make any changes in my article, I would like to ask some questions. I have read the article \u201cScheimpflug Photographic Diagnosis of PellucidMarginal Degeneration\u201d by Walker RN \net al.<\/i> (2008), I will refer to it as article number 1; and the article \u201cWhat\u2019s in a name: Keratoconus, Pellucid Marginal Degeneration and Related Thinning Disorders\u201d by Belin MW \net al.<\/i> (2011), I will refer to it as article number 2. Unfortunately I could not have the third article which is \u201cSimplified Nomenclature for Describing Keratoconus\u201d by Belin MW \net al.<\/i> (2012). I would be very thankful if you could provide me with it and it would be so kind of you.The questions are:\n1.<\/b> In article 2: the author stated: \u201cin our original review article PMD was described as a typically bilateral, clear, inferior, peripheral corneal thinning disorder, characterized by a narrow band of corneal thinning (often approaching 20% normal thickness) separated from the inferior limbus by a relatively uninvolved area 1 to 2 mm in width.\u201d However, nothing was mentioned in this article and in article 1 about the new definition of PMD and whether it is bilateral or can be unilateral. So the question is: can PMD be unilateral?\n2.<\/b> In article 2 the author stated: \u201cErtan and Bahadir in 2006 described the use of the femtosecond laser and intrastromal rings to correct PMD. While no corneal thickness maps were presented, the posterior elevation maps were typical of KCN and not classic PMD.\u201d But may I ask: what is typical of KCN and not classic PMD on the posterior elevation map? The same question about what the author mentioned about Kubaloglu and associates.\n3. <\/b>How do you define that the cone is central, paracentral or peripheral on the elevation map with the BFS mode? I mean when do say the the cone is central (within 3 mm, 4mm, 5mm\u2026.) since this was not mentioned in both articles?\n4.<\/b>In article 2, the author recommended that \u201cextrapolated data should not be displayed\u201d and thus the 9mm scale should be used, therefore according to this recommendation, the peripheral part of the cornea will not be displayed or estimated and the pachymetric changes of PMD will not be evaluated?! At the same time, the authors use the extrapolated areas in many of their talks during conferences and articles!\n5.<\/b> In article 1: how could the authors recognize the thinning in case of focal edema? And how could they depend on Placido or even Scheimpflug in this very distorted cornea? They also stated:\u201d a bilateral superior flattening\u201d in figure 4 but only OS was displayed; What about OD, is it possible to see the flattening on OD despite edema even if it was focal and inferior?\n6.<\/b> In article 1, page 2: the author stated:\u201d thinning within 2 mm of the limbus, and a more normal corneal thickness inferior to the band of thinning.\u201d But all of that lie in the extrapolated area which should not be displayed as the author recommended in article 2!Sincerely Yours, Mazen","URL":"https:\/\/f1000research.com\/articles\/1-48\/v1#referee-comment-79","order":3,"name":"referee-comment-79","label":"Referee Comment","group":{"name":"article-reports","label":"Article Reports"}},{"value":"Michael Belin<\/b>; \nPosted: 13 Dec 2012<\/i>; Dr. Sinjab, I sent you the requested article via this publisher.In reference to the findings of KCN vs PMD on the posterior elevation, Inf KCN shows the classic positive islands of elevation when using the standard BFS (sphere). Elevation maps are not overly useful in true PMD because the cornea is so flat in the central 8.0 mm zone that the reference surface is so flat as to not accentuate the pathology. This is why the pach map is the most important (opened up to show the full cornea)As far as which is a central cone, vs paracentral, vs peripheral. I do not believe there is anything established but I use the central 3.0 for \u201ccentral\u201d and outside 6.0 for \u201cinferior\u201d but it is often just a visual description.In general we limit our display to 9.0 mm as for routine screening this is easier. That is not the case for peripheral disease. In cases of true PMD, you have to show the entire cornea. It is true that the more peripheral the data the more likely it will be extrapolated but if the Pentacam produced a thickness reading it is useful for visual diagnosis. If the number is produced, but extrapolated, it means it did not meet the strict machine criteria. If no number (thickness) is produced then the map needs to be repeated as there is no useful data.In article 1 the thinning was easily seen in the other eye as this was bilateral. The Scheimplfug images were still reliable in the eye with the hydrops except for the far periphery so the central and paracentral flattening could still be seen. The reason both eyes were not shown in all displays is a limit of the journal for case reports.","URL":"https:\/\/f1000research.com\/articles\/1-48\/v1#referee-comment-109","order":4,"name":"referee-comment-109","label":"Referee Comment","group":{"name":"article-reports","label":"Article Reports"}},{"value":"Mazen Sinjab<\/b>; \nPosted: 13 Dec 2012<\/i>; Thank you very much Prof. Belin, and many thank to this journal that gave me the opportunity to learn from you. You were so kind to send me the article.But may I ask you: could PMD be unilateral?Sincerely Yours, Mazen","URL":"https:\/\/f1000research.com\/articles\/1-48\/v1#referee-comment-110","order":5,"name":"referee-comment-110","label":"Referee Comment","group":{"name":"article-reports","label":"Article Reports"}},{"value":"Michael Belin<\/b>; \nPosted: 14 Dec 2012<\/i>; UNILATERAL \u2013 I don\u2019t know. I would guess that if PMD (as is KCN) is ultimately a disorder of collagen (i.e. genetic \/ biochemical) that the collagen would be abnormal in both eyes though clinical presentations may be unilateral or highly asymmetic.","URL":"https:\/\/f1000research.com\/articles\/1-48\/v1#referee-comment-150","order":6,"name":"referee-comment-150","label":"Referee Comment","group":{"name":"article-reports","label":"Article Reports"}},{"value":"10.5256\/f1000research.217.r379, Natalie Afshari, Department of Ophthalmology, Duke University School of Medicine, Durham, NC, USA, 27 Nov 2012, version 1, indexed","URL":"https:\/\/f1000research.com\/articles\/1-48\/v1#referee-response-379","order":7,"name":"referee-response-379","label":"Referee Report","group":{"name":"article-reports","label":"Article Reports"}},{"value":"Mazen Sinjab<\/b>; \nPosted: 27 Nov 2012<\/i>; Dear Professor Afshari,During my past 16 years of practice as a refractive surgeon, I have seen more than 3000 cases of keratoconus and ectatic corneal disorders at my center and in the refractive clinic in the Damascus University hospital, and many of those cases were referred to me for a second opinion. This number seems to be large, but the cause behind it was that in Syria such diseases are relatively common due to close intermarriage, environment and to the high prevalence of vernal keratoconjunctivitis; this registers an incidence higher than the international one which is 1:2000, to be about 1:400 in Syria, and in some well known regions in Syria one can say 1:100. PMD consists of about 20% of the seen cases, and it is seen not only in adults but also in young patients, which gives the disease a more aggressive nature. The same can be said about KC, I have seen many cases with ages younger than 10 years old (the youngest was 4 years old!). Due to such a high number of cases that I have seen, I could recognize cases that lie in between KC and PMD although both entities have their own tomographic features; and that was the idea behind my study.","URL":"https:\/\/f1000research.com\/articles\/1-48\/v1#referee-comment-78","order":8,"name":"referee-comment-78","label":"Referee Comment","group":{"name":"article-reports","label":"Article Reports"}},{"value":"The author(s) declared that no grants were involved in supporting this work","order":9,"name":"grant-information","label":"Grant Information"},{"value":"This is an open access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Data associated with the article are available under the terms of the Creative Commons Zero \"No rights reserved\" data waiver (CC0 1.0 Public domain dedication).","order":0,"name":"copyright-info","label":"Copyright"}]}}