{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,13]],"date-time":"2026-06-13T10:20:19Z","timestamp":1781346019326,"version":"3.54.1"},"reference-count":52,"publisher":"Wiley","issue":"2","license":[{"start":{"date-parts":[[2015,11,2]],"date-time":"2015-11-02T00:00:00Z","timestamp":1446422400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Acta Ophthalmologica"],"published-print":{"date-parts":[[2016,3]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Purpose<\/jats:title><jats:p>To evaluate the differences in central and non\u2010central keratoconus (based on cone location), and their effect on the objective screening thresholds for keratoconus.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>This comparative case series was performed at tertiary care cornea and refractive surgery service. Three groups were made: <jats:styled-content style=\"fixed-case\">KC<\/jats:styled-content> apex within central 2 mm (central keratoconus, <jats:italic>n<\/jats:italic>\u00a0=\u00a050), apex outside central 2mm (non\u2010central keratoconus, <jats:italic>n<\/jats:italic>\u00a0=\u00a050) and normal controls (<jats:italic>n<\/jats:italic>\u00a0=\u00a0100, with 50 cases each with apex within and outside central 2 mm). All cases underwent clinical evaluation and corneal topography (<jats:styled-content style=\"fixed-case\">CSO<\/jats:styled-content>, Sirius, Italy). Apex keratometry (ApexK), simulated keratometry at 3\u00a0mm (SimK), central corneal thickness (<jats:styled-content style=\"fixed-case\">CCT<\/jats:styled-content>) and minimum corneal thickness (<jats:styled-content style=\"fixed-case\">MCT<\/jats:styled-content>), anterior corneal higher\u2010order aberrations root mean square (<jats:styled-content style=\"fixed-case\">HOARMS<\/jats:styled-content>), and Zernike's coefficients up to fourth order at different zones were measured.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>In spite of the keratoconic groups having comparable ApexK (p\u00a0&gt;\u00a00.05), central keratoconus had higher SimK and thinner <jats:styled-content style=\"fixed-case\">CCT<\/jats:styled-content> and <jats:styled-content style=\"fixed-case\">MCT<\/jats:styled-content> (p\u00a0&lt;\u00a00.001). <jats:styled-content style=\"fixed-case\">HOARMS<\/jats:styled-content> was significantly more for central keratoconus at 3\u00a0mm zones. These findings had moderate to large effect size (Cohen's d). Receiver operating curve analysis was carried out to compare central keratoconus and non\u2010central keratoconus with control group. ApexK and <jats:styled-content style=\"fixed-case\">HOARMS<\/jats:styled-content> had best discriminative parameters. Using single parametric suspicion cut\u2010offs of \u2018either SimK steep &gt;47.2\u00a0D or <jats:styled-content style=\"fixed-case\">CCT<\/jats:styled-content>\u00a0&lt;\u00a0491.6\u00a0<jats:italic>\u03bc<\/jats:italic>\u2019 had a good sensitivity (0.98) for central keratoconus, but not for non\u2010central keratoconus (0.80). Changing this cut\u2010off to \u2018either SimK steep <jats:italic>K<\/jats:italic>\u00a0\u2265\u00a045.8\u00a0D or <jats:styled-content style=\"fixed-case\">CCT<\/jats:styled-content>\u00a0\u2264\u00a0503\u00a0<jats:italic>\u03bc<\/jats:italic>\u2019 gave a sensitivity and specificity of 0.95 and 0.87 for non\u2010central keratoconus and 0.99 and 0.87 for central keratoconus.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>Non\u2010central keratoconus has lesser effect on SimK, pachymetry and smaller\u2010aperture <jats:styled-content style=\"fixed-case\">HOARMS<\/jats:styled-content>. Using \u2018SimK steep &gt;47.2\u00a0D or <jats:styled-content style=\"fixed-case\">CCT<\/jats:styled-content>\u00a0&lt;\u00a0491.6\u00a0<jats:italic>\u03bc<\/jats:italic>\u2019 may miss timely referral for topography in many of these cases. Using more stringent criteria of SimK steep <jats:italic>K<\/jats:italic>\u00a0\u2265\u00a045.8\u00a0D or <jats:styled-content style=\"fixed-case\">CCT<\/jats:styled-content>\u00a0\u2264\u00a0503\u00a0<jats:italic>\u03bc<\/jats:italic> to get a corneal topography done to rule out keratoconus is recommended, especially in cohorts with higher risk.<\/jats:p><\/jats:sec>","DOI":"10.1111\/aos.12899","type":"journal-article","created":{"date-parts":[[2015,11,2]],"date-time":"2015-11-02T13:31:45Z","timestamp":1446471105000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":28,"title":["Differences in central and non\u2010central keratoconus, and their effect on the objective screening thresholds for keratoconus"],"prefix":"10.1111","volume":"94","author":[{"given":"Gaurav","family":"Prakash","sequence":"first","affiliation":[{"name":"Department of Cornea and Refractive Surgery NMC Eye Care New Medical Center Specialty Hospital Abu Dhabi United Arab Emirates"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dhruv","family":"Srivastava","sequence":"additional","affiliation":[{"name":"Department of Cornea and Refractive Surgery NMC Eye Care New Medical Center Specialty Hospital Abu Dhabi United Arab Emirates"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sounak","family":"Choudhuri","sequence":"additional","affiliation":[{"name":"Department of Cornea and Refractive Surgery NMC Eye Care New Medical Center Specialty Hospital Abu Dhabi United Arab Emirates"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sandeep Mark","family":"Thirumalai","sequence":"additional","affiliation":[{"name":"Department of Cornea and Refractive Surgery NMC Eye Care New Medical Center Specialty Hospital Abu Dhabi United Arab Emirates"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ruthchel","family":"Bacero","sequence":"additional","affiliation":[{"name":"Department of Cornea and Refractive Surgery NMC Eye Care New Medical Center Specialty Hospital Abu Dhabi United Arab Emirates"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2015,11,2]]},"reference":[{"key":"e_1_2_5_2_1","doi-asserted-by":"publisher","DOI":"10.3928\/1081-597X-20060601-05"},{"key":"e_1_2_5_3_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.jcrs.2010.10.046"},{"key":"e_1_2_5_4_1","doi-asserted-by":"publisher","DOI":"10.3928\/1081597X-20110721-01"},{"key":"e_1_2_5_5_1","unstructured":"American Academy of Ophthalmology Cornea\/External Disease Panel(2013):Preferred practice pattern\u00aeguidelines. 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