{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T19:28:50Z","timestamp":1786649330864,"version":"build-2736575974"},"reference-count":38,"publisher":"Ovid Technologies (Wolters Kluwer Health)","issue":"6","content-domain":{"domain":["lww.com","ovid.com"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2021,6]]},"abstract":"<jats:sec>\n                    <jats:title>Purpose:<\/jats:title>\n                    <jats:p>The aim of this study was to test a method for estimating corneal rigidity before and after cross-linking (CXL) using a Schi\u00f8tz tonometer.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods:<\/jats:title>\n                    <jats:p>\n                      The study was performed in the Kyiv City Clinical Ophthalmological Hospital \u201cEye Microsurgical Center\u201d, Ukraine. This was a prospective, consecutive, randomized, masked, case-by-case, clinical study. Corneal rigidity, indicated by the gradient (G) between lg applied weight and corresponding lg scale reading during Schi\u00f8tz tonometry, were obtained by increasing (A-mode) then reducing (D-mode) weights by two operators [A] in keratoconus, post-CXL and control subjects for estimation of (i) interoperator and (ii) intersessional errors, (iii) intergroup differences; [B] before and after CXL. Central corneal thickness CCT was measured by scanning slit pachymetry. ANOVA,\n                      <jats:italic toggle=\"yes\">t<\/jats:italic>\n                      tests, linear regression were the statistical tools used.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results:<\/jats:title>\n                    <jats:p>\n                      Average interoperator difference (\u0394G) was \u20130.120 (SD = \u00b10.294, 95%CI = \u20130.175 to \u20130.066). A significant correlation between \u0394G and the mean of each pair of G values was found (\n                      <jats:italic toggle=\"yes\">r = \u2013<\/jats:italic>\n                      0.196,\n                      <jats:italic toggle=\"yes\">n =<\/jats:italic>\n                      112,\n                      <jats:italic toggle=\"yes\">P<\/jats:italic>\n                      = 0.038). Intersessional differences in mean G values were insignificant (\n                      <jats:italic toggle=\"yes\">P<\/jats:italic>\n                      &gt; 0.05). There was a significant correlation between G at first session (X\n                      <jats:sub>1<\/jats:sub>\n                      ) and difference between sessions (\u0394G) [Operator 1, \u0394G = 0.598x\n                      <jats:sub>1<\/jats:sub>\n                      \u20130.461,\n                      <jats:italic toggle=\"yes\">r<\/jats:italic>\n                      = 0.601,\n                      <jats:italic toggle=\"yes\">n =<\/jats:italic>\n                      27,\n                      <jats:italic toggle=\"yes\">P<\/jats:italic>\n                      = 0.009]. Significant intergroup differences in G were found (Operator 1, one-way ANOVA, F = 4.489,\n                      <jats:italic toggle=\"yes\">P<\/jats:italic>\n                      = 0.014). The difference (\u0394) between the pre-(X\n                      <jats:sub>2<\/jats:sub>\n                      ) and post-CXL treatment G values was significantly associated with the pre-CXL treatment value (Operator 1, \u0394 = 1.970x\n                      <jats:sub>2<\/jats:sub>\n                      -1.622,\n                      <jats:italic toggle=\"yes\">r<\/jats:italic>\n                      = 0.642,\n                      <jats:italic toggle=\"yes\">n =<\/jats:italic>\n                      18,\n                      <jats:italic toggle=\"yes\">P<\/jats:italic>\n                      = &lt;.001). G values were correlated with CCT in keratoconus and post-CXL.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion:<\/jats:title>\n                    <jats:p>Corneal rigidity (G) estimated using the Schi\u00f8tz tonometer can be useful for detecting changes after CXL. However, G values are linked to CCT, can vary from time-to-time and the procedure is operator dependent.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.4103\/ijo.ijo_1820_20","type":"journal-article","created":{"date-parts":[[2021,6,2]],"date-time":"2021-06-02T10:42:08Z","timestamp":1622630528000},"page":"1531-1536","update-policy":"https:\/\/doi.org\/10.1097\/lww.0000000000001000","source":"Crossref","is-referenced-by-count":1,"title":["The effect of corneal crosslinking on the rigidity of the cornea estimated using a modified algorithm for the Schi\u00f8tz tonometer"],"prefix":"10.4103","volume":"69","author":[{"given":"Larysa","family":"Tutchenko","sequence":"first","affiliation":[{"name":"Department of Ophthalmology, Shupyk National Medical Academy of Postgraduate Education, Kyiv, Ukraine"},{"name":"Kyiv City Clinical Ophthalmological Hospital \u201cEye Microsurgical Center\u201d, Kyiv, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sudi","family":"Patel","sequence":"additional","affiliation":[{"name":"NHS National Services Scotland, Edinburgh, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mykhailo","family":"Skovron","sequence":"additional","affiliation":[{"name":"Kyiv City Clinical Ophthalmological Hospital \u201cEye Microsurgical Center\u201d, Kyiv, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Olha","family":"Horak","sequence":"additional","affiliation":[{"name":"Kyiv City Clinical Ophthalmological Hospital \u201cEye Microsurgical Center\u201d, Kyiv, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Oleksiy","family":"Voytsekhivskyy","sequence":"additional","affiliation":[{"name":"Kyiv City Clinical Ophthalmological Hospital \u201cEye Microsurgical Center\u201d, Kyiv, Ukraine"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"276","published-online":{"date-parts":[[2021,5,21]]},"reference":[{"key":"R1-20251004","doi-asserted-by":"crossref","first-page":"256","DOI":"10.4103\/0974-9233.58418","article-title":"Riboflavin-ultraviolet A corneal cross-linking for keratoconus","volume":"16","author":"El-Raggal","year":"2009","journal-title":"Middle East Afr J Ophthalmol"},{"key":"R2-20251004","doi-asserted-by":"crossref","first-page":"798","DOI":"10.3928\/1081597X-20121011-09","article-title":"Corneal collagen crosslinking for non-ectatic disorders: A systematic review","volume":"28","author":"Bettis","year":"2012","journal-title":"J Refract Surg"},{"key":"R3-20251004","doi-asserted-by":"crossref","first-page":"583","DOI":"10.1097\/ICO.0b013e31825e8414","article-title":"Prospective study of corneal collagen cross-linking efficacy and tolerance in the treatment of keratoconus and corneal ectasia: 3-year results","volume":"32","author":"Poli","year":"2013","journal-title":"Cornea"},{"key":"R4-20251004","doi-asserted-by":"crossref","first-page":"97","DOI":"10.1006\/exer.1997.0410","article-title":"Induction of cross-links in corneal tissue","volume":"66","author":"Spoerl","year":"1998","journal-title":"Exp Eye Res"},{"key":"R5-20251004","doi-asserted-by":"crossref","first-page":"452","DOI":"10.3928\/1081597X-20110106-01","article-title":"Detection of biomechanical changes after corneal cross-linking using Ocular Response Analyzer software","volume":"27","author":"Spoerl","year":"2011","journal-title":"J Refract Surg"},{"key":"R6-20251004","doi-asserted-by":"crossref","first-page":"1728","DOI":"10.1016\/j.jcrs.2010.06.056","article-title":"Biomechanical parameters of the cornea after collagen crosslinking measured by waveform analysis","volume":"36","author":"Sedaghat","year":"2010","journal-title":"J Cataract Refract Surg"},{"key":"R7-20251004","doi-asserted-by":"crossref","first-page":"669","DOI":"10.3928\/1081597X-20100331-01","article-title":"Intra- and postoperative variation in ocular response analyzer parameters in keratoconic eyes after corneal cross-linking","volume":"26","author":"Vinciguerra","year":"2010","journal-title":"J Refract Surg"},{"key":"R8-20251004","doi-asserted-by":"crossref","first-page":"498","DOI":"10.1097\/ICO.0b013e318190734d","article-title":"Can we measure corneal biomechanical changes after collagen cross-linking in eyes with keratoconus? 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