Assessing the accuracy of Orbscan II post-LASIK: apparent keratectasia is paradoxically associated with anterior chamber depth reduction in successful procedures

Purpose: To establish a relationship between the forward protrusion of the cornea (keratectasia), following successful LASIK, and anterior chamber depth. Methods: One hundred and fifteen eyes of 59 patients who had undergone Zyoptix LASIK and 39 eyes of 21 patients who had undergone PlanoScan LASIK...

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Veröffentlicht in:Clinical & experimental ophthalmology 2005-04, Vol.33 (2), p.147-152
Hauptverfasser: Cairns, Gerard, Ormonde, Susan E, Gray, Trevor, Hadden, O Bruce, Morris, Tony, Ring, Peter, McGhee, Charles NJ
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container_issue 2
container_start_page 147
container_title Clinical & experimental ophthalmology
container_volume 33
creator Cairns, Gerard
Ormonde, Susan E
Gray, Trevor
Hadden, O Bruce
Morris, Tony
Ring, Peter
McGhee, Charles NJ
description Purpose: To establish a relationship between the forward protrusion of the cornea (keratectasia), following successful LASIK, and anterior chamber depth. Methods: One hundred and fifteen eyes of 59 patients who had undergone Zyoptix LASIK and 39 eyes of 21 patients who had undergone PlanoScan LASIK at the Eye Institute, Centre for Refractive Surgery, Remuera, Auckland, New Zealand, were included in the study. The results of Orbscan II acquisitions, taken before and 8.3 weeks ± 4.0 (mean ± standard deviation) following the procedure, were analysed to determine the amount of forward protrusion of the central 2 mm diameter of the posterior surface. The apparent keratectasia was then related to the Orbscan II anterior chamber depth (ACD) measurement in a linear mixed model analysis that included ‘right or left eye’, ‘sex’, ‘type of LASIK procedure’, ‘change in pachymetry’, ‘postoperative pachymetry’, ‘change in anterior corneal curvature’, ‘postoperative anterior corneal curvature’, ‘planned ablation depth’ and ‘time until follow‐up’ as factors and covariates. Results: The mean ± SD amount of keratectasia determined by Orbscan II was 22.8 ± 26.8 µm for the Zyoptix group and 16.9 ± 24.6 µm for the PlanoScan group. The reduction in depth of the anterior chamber was 14.7 ± 79.3 µm for the Zyoptix group and 18.2 ± 68.8 µm for the PlanoScan group. The mixed model analysis demonstrated strong relationships with postoperative pachymetry and change in anterior corneal curvature (P 
doi_str_mv 10.1111/j.1442-9071.2005.00975.x
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Methods: One hundred and fifteen eyes of 59 patients who had undergone Zyoptix LASIK and 39 eyes of 21 patients who had undergone PlanoScan LASIK at the Eye Institute, Centre for Refractive Surgery, Remuera, Auckland, New Zealand, were included in the study. The results of Orbscan II acquisitions, taken before and 8.3 weeks ± 4.0 (mean ± standard deviation) following the procedure, were analysed to determine the amount of forward protrusion of the central 2 mm diameter of the posterior surface. The apparent keratectasia was then related to the Orbscan II anterior chamber depth (ACD) measurement in a linear mixed model analysis that included ‘right or left eye’, ‘sex’, ‘type of LASIK procedure’, ‘change in pachymetry’, ‘postoperative pachymetry’, ‘change in anterior corneal curvature’, ‘postoperative anterior corneal curvature’, ‘planned ablation depth’ and ‘time until follow‐up’ as factors and covariates. Results: The mean ± SD amount of keratectasia determined by Orbscan II was 22.8 ± 26.8 µm for the Zyoptix group and 16.9 ± 24.6 µm for the PlanoScan group. The reduction in depth of the anterior chamber was 14.7 ± 79.3 µm for the Zyoptix group and 18.2 ± 68.8 µm for the PlanoScan group. The mixed model analysis demonstrated strong relationships with postoperative pachymetry and change in anterior corneal curvature (P &lt; 0.001 and P &lt; 0.001, respectively). Furthermore, the statistical model showed a marked significant difference in the Orbscan II assessment of keratectasia and change in ACD (P &lt; 0.001). Conclusion: Using the Orbscan II device, the forward protrusion of the posterior corneal surface appears to coincide with a paradoxical reduction in depth of the anterior chamber. Although the keratectasia found in this study is accompanied by thin postoperative corneas and larger central pachymetry change, the contradictory decrease in anterior chamber depth creates uncertainty of measurement, and of ectasia as a mechanism of regression.</description><identifier>ISSN: 1442-6404</identifier><identifier>EISSN: 1442-9071</identifier><identifier>DOI: 10.1111/j.1442-9071.2005.00975.x</identifier><identifier>PMID: 15807822</identifier><language>eng</language><publisher>Oxford, UK: Blackwell Science Pty</publisher><subject>Adult ; Anterior Chamber - pathology ; cornea ; Cornea - pathology ; Corneal Topography - methods ; Dilatation, Pathologic - diagnosis ; Female ; Humans ; keratectasia ; Keratomileusis, Laser In Situ ; LASIK ; Male ; Middle Aged ; Orbscan ; Postoperative Care ; Reproducibility of Results ; Retrospective Studies ; topography</subject><ispartof>Clinical &amp; experimental ophthalmology, 2005-04, Vol.33 (2), p.147-152</ispartof><lds50>peer_reviewed</lds50><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-c4045-5132123c1058c5ed32b8b1686714ff1c279e27734680f92d081f3a3d3c29487f3</citedby><cites>FETCH-LOGICAL-c4045-5132123c1058c5ed32b8b1686714ff1c279e27734680f92d081f3a3d3c29487f3</cites></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><linktopdf>$$Uhttps://onlinelibrary.wiley.com/doi/pdf/10.1111%2Fj.1442-9071.2005.00975.x$$EPDF$$P50$$Gwiley$$H</linktopdf><linktohtml>$$Uhttps://onlinelibrary.wiley.com/doi/full/10.1111%2Fj.1442-9071.2005.00975.x$$EHTML$$P50$$Gwiley$$H</linktohtml><link.rule.ids>314,776,780,1411,27901,27902,45550,45551</link.rule.ids><backlink>$$Uhttps://www.ncbi.nlm.nih.gov/pubmed/15807822$$D View this record in MEDLINE/PubMed$$Hfree_for_read</backlink></links><search><creatorcontrib>Cairns, Gerard</creatorcontrib><creatorcontrib>Ormonde, Susan E</creatorcontrib><creatorcontrib>Gray, Trevor</creatorcontrib><creatorcontrib>Hadden, O Bruce</creatorcontrib><creatorcontrib>Morris, Tony</creatorcontrib><creatorcontrib>Ring, Peter</creatorcontrib><creatorcontrib>McGhee, Charles NJ</creatorcontrib><title>Assessing the accuracy of Orbscan II post-LASIK: apparent keratectasia is paradoxically associated with anterior chamber depth reduction in successful procedures</title><title>Clinical &amp; experimental ophthalmology</title><addtitle>Clin Exp Ophthalmol</addtitle><description>Purpose: To establish a relationship between the forward protrusion of the cornea (keratectasia), following successful LASIK, and anterior chamber depth. Methods: One hundred and fifteen eyes of 59 patients who had undergone Zyoptix LASIK and 39 eyes of 21 patients who had undergone PlanoScan LASIK at the Eye Institute, Centre for Refractive Surgery, Remuera, Auckland, New Zealand, were included in the study. The results of Orbscan II acquisitions, taken before and 8.3 weeks ± 4.0 (mean ± standard deviation) following the procedure, were analysed to determine the amount of forward protrusion of the central 2 mm diameter of the posterior surface. The apparent keratectasia was then related to the Orbscan II anterior chamber depth (ACD) measurement in a linear mixed model analysis that included ‘right or left eye’, ‘sex’, ‘type of LASIK procedure’, ‘change in pachymetry’, ‘postoperative pachymetry’, ‘change in anterior corneal curvature’, ‘postoperative anterior corneal curvature’, ‘planned ablation depth’ and ‘time until follow‐up’ as factors and covariates. Results: The mean ± SD amount of keratectasia determined by Orbscan II was 22.8 ± 26.8 µm for the Zyoptix group and 16.9 ± 24.6 µm for the PlanoScan group. The reduction in depth of the anterior chamber was 14.7 ± 79.3 µm for the Zyoptix group and 18.2 ± 68.8 µm for the PlanoScan group. The mixed model analysis demonstrated strong relationships with postoperative pachymetry and change in anterior corneal curvature (P &lt; 0.001 and P &lt; 0.001, respectively). Furthermore, the statistical model showed a marked significant difference in the Orbscan II assessment of keratectasia and change in ACD (P &lt; 0.001). Conclusion: Using the Orbscan II device, the forward protrusion of the posterior corneal surface appears to coincide with a paradoxical reduction in depth of the anterior chamber. Although the keratectasia found in this study is accompanied by thin postoperative corneas and larger central pachymetry change, the contradictory decrease in anterior chamber depth creates uncertainty of measurement, and of ectasia as a mechanism of regression.</description><subject>Adult</subject><subject>Anterior Chamber - pathology</subject><subject>cornea</subject><subject>Cornea - pathology</subject><subject>Corneal Topography - methods</subject><subject>Dilatation, Pathologic - diagnosis</subject><subject>Female</subject><subject>Humans</subject><subject>keratectasia</subject><subject>Keratomileusis, Laser In Situ</subject><subject>LASIK</subject><subject>Male</subject><subject>Middle Aged</subject><subject>Orbscan</subject><subject>Postoperative Care</subject><subject>Reproducibility of Results</subject><subject>Retrospective Studies</subject><subject>topography</subject><issn>1442-6404</issn><issn>1442-9071</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>2005</creationdate><recordtype>article</recordtype><sourceid>EIF</sourceid><recordid>eNqNkU1z0zAQhj0MDC2Fv8DoxM1GH7YlM1wymbakBMLwedTI8poodWyjlafJz-k_rUIy5You2tl93t2V3iQhjGYsnrebjOU5TysqWcYpLTJKK1lkuyfJ-WPh6Skuc5qfJS8QNzSSXJTPkzNWKCoV5-fJ_QwREF3_m4Q1EGPt5I3dk6ElK1-jNT1ZLMg4YEiXs2-Lj--IGUfjoQ_kFrwJYINBZ4hDEtOmGXbOmq7bE4M4WBeBhty5sCamD-Dd4Ildm20NnjQwxrSHZrLBDT1xPcHJ2rhMO3Vk9IONJQ_4MnnWmg7h1em-SH5cXX6ff0iXq-vFfLZMbXxgkRZMcMaFZbRQtoBG8FrVrFSlZHnbMstlBVxKkZeKthVvqGKtMKIRlle5kq24SN4c-8bRfybAoLcOLXSd6WGYUJdS0pxyGkF1BK0fED20evRua_xeM6oP9uiNPvy8PrigD_bov_boXZS-Ps2Y6i00_4QnPyLw_gjcuQ72_91Yzy9XMYjy9Ch3GGD3KDf-Nq4vIvnr87X-efPl69Wn-Y0W4gH1Ra9y</recordid><startdate>200504</startdate><enddate>200504</enddate><creator>Cairns, Gerard</creator><creator>Ormonde, Susan E</creator><creator>Gray, Trevor</creator><creator>Hadden, O Bruce</creator><creator>Morris, Tony</creator><creator>Ring, Peter</creator><creator>McGhee, Charles NJ</creator><general>Blackwell Science Pty</general><scope>BSCLL</scope><scope>CGR</scope><scope>CUY</scope><scope>CVF</scope><scope>ECM</scope><scope>EIF</scope><scope>NPM</scope><scope>AAYXX</scope><scope>CITATION</scope><scope>7X8</scope></search><sort><creationdate>200504</creationdate><title>Assessing the accuracy of Orbscan II post-LASIK: apparent keratectasia is paradoxically associated with anterior chamber depth reduction in successful procedures</title><author>Cairns, Gerard ; Ormonde, Susan E ; Gray, Trevor ; Hadden, O Bruce ; Morris, Tony ; Ring, Peter ; McGhee, Charles NJ</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-c4045-5132123c1058c5ed32b8b1686714ff1c279e27734680f92d081f3a3d3c29487f3</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>2005</creationdate><topic>Adult</topic><topic>Anterior Chamber - pathology</topic><topic>cornea</topic><topic>Cornea - pathology</topic><topic>Corneal Topography - methods</topic><topic>Dilatation, Pathologic - diagnosis</topic><topic>Female</topic><topic>Humans</topic><topic>keratectasia</topic><topic>Keratomileusis, Laser In Situ</topic><topic>LASIK</topic><topic>Male</topic><topic>Middle Aged</topic><topic>Orbscan</topic><topic>Postoperative Care</topic><topic>Reproducibility of Results</topic><topic>Retrospective Studies</topic><topic>topography</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Cairns, Gerard</creatorcontrib><creatorcontrib>Ormonde, Susan E</creatorcontrib><creatorcontrib>Gray, Trevor</creatorcontrib><creatorcontrib>Hadden, O Bruce</creatorcontrib><creatorcontrib>Morris, Tony</creatorcontrib><creatorcontrib>Ring, Peter</creatorcontrib><creatorcontrib>McGhee, Charles NJ</creatorcontrib><collection>Istex</collection><collection>Medline</collection><collection>MEDLINE</collection><collection>MEDLINE (Ovid)</collection><collection>MEDLINE</collection><collection>MEDLINE</collection><collection>PubMed</collection><collection>CrossRef</collection><collection>MEDLINE - Academic</collection><jtitle>Clinical &amp; experimental ophthalmology</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Cairns, Gerard</au><au>Ormonde, Susan E</au><au>Gray, Trevor</au><au>Hadden, O Bruce</au><au>Morris, Tony</au><au>Ring, Peter</au><au>McGhee, Charles NJ</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>Assessing the accuracy of Orbscan II post-LASIK: apparent keratectasia is paradoxically associated with anterior chamber depth reduction in successful procedures</atitle><jtitle>Clinical &amp; experimental ophthalmology</jtitle><addtitle>Clin Exp Ophthalmol</addtitle><date>2005-04</date><risdate>2005</risdate><volume>33</volume><issue>2</issue><spage>147</spage><epage>152</epage><pages>147-152</pages><issn>1442-6404</issn><eissn>1442-9071</eissn><abstract>Purpose: To establish a relationship between the forward protrusion of the cornea (keratectasia), following successful LASIK, and anterior chamber depth. Methods: One hundred and fifteen eyes of 59 patients who had undergone Zyoptix LASIK and 39 eyes of 21 patients who had undergone PlanoScan LASIK at the Eye Institute, Centre for Refractive Surgery, Remuera, Auckland, New Zealand, were included in the study. The results of Orbscan II acquisitions, taken before and 8.3 weeks ± 4.0 (mean ± standard deviation) following the procedure, were analysed to determine the amount of forward protrusion of the central 2 mm diameter of the posterior surface. The apparent keratectasia was then related to the Orbscan II anterior chamber depth (ACD) measurement in a linear mixed model analysis that included ‘right or left eye’, ‘sex’, ‘type of LASIK procedure’, ‘change in pachymetry’, ‘postoperative pachymetry’, ‘change in anterior corneal curvature’, ‘postoperative anterior corneal curvature’, ‘planned ablation depth’ and ‘time until follow‐up’ as factors and covariates. Results: The mean ± SD amount of keratectasia determined by Orbscan II was 22.8 ± 26.8 µm for the Zyoptix group and 16.9 ± 24.6 µm for the PlanoScan group. The reduction in depth of the anterior chamber was 14.7 ± 79.3 µm for the Zyoptix group and 18.2 ± 68.8 µm for the PlanoScan group. The mixed model analysis demonstrated strong relationships with postoperative pachymetry and change in anterior corneal curvature (P &lt; 0.001 and P &lt; 0.001, respectively). Furthermore, the statistical model showed a marked significant difference in the Orbscan II assessment of keratectasia and change in ACD (P &lt; 0.001). Conclusion: Using the Orbscan II device, the forward protrusion of the posterior corneal surface appears to coincide with a paradoxical reduction in depth of the anterior chamber. Although the keratectasia found in this study is accompanied by thin postoperative corneas and larger central pachymetry change, the contradictory decrease in anterior chamber depth creates uncertainty of measurement, and of ectasia as a mechanism of regression.</abstract><cop>Oxford, UK</cop><pub>Blackwell Science Pty</pub><pmid>15807822</pmid><doi>10.1111/j.1442-9071.2005.00975.x</doi><tpages>6</tpages></addata></record>
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source MEDLINE; Wiley Online Library Journals Frontfile Complete
subjects Adult
Anterior Chamber - pathology
cornea
Cornea - pathology
Corneal Topography - methods
Dilatation, Pathologic - diagnosis
Female
Humans
keratectasia
Keratomileusis, Laser In Situ
LASIK
Male
Middle Aged
Orbscan
Postoperative Care
Reproducibility of Results
Retrospective Studies
topography
title Assessing the accuracy of Orbscan II post-LASIK: apparent keratectasia is paradoxically associated with anterior chamber depth reduction in successful procedures
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