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https://observatorio.fm.usp.br/handle/OPI/9817
Title: | Role of Percent Tissue Altered on Ectasia After LASIK in Eyes With Suspicious Topography |
Authors: | SANTHIAGO, Marcony R.; SMADJA, David; WILSON, Steven E.; KRUEGER, Ronald R.; MONTEIRO, Mario L. R.; RANDLEMAN, J. Bradley |
Citation: | JOURNAL OF REFRACTIVE SURGERY, v.31, n.4, p.258-U163, 2015 |
Abstract: | PURPOSE: To investigate the association of the percent tissue altered (PTA) with the occurrence of ectasia after LASIK in eyes with suspicious preoperative corneal topography. METHODS: This retrospective comparative case-control study compared associations of reported ectasia risk factors in 129 eyes, including 57 eyes with suspicious preoperative Placido-based corneal topography that developed ectasia after LASIK (suspect ectasia group), 32 eyes with suspicious topography that remained stable for at least 3 years after LASIK (suspect control group), and 30 eyes that developed ectasia with bilateral normal topography (normal topography ectasia group). Groups were subdivided based on topographic asymmetry into high-or low-suspect groups. The PTA, preoperative central corneal thickness (CCT), residual stromal bed (RSB), and age (years) were evaluated in univariate and multivariate analyses. RESULTS: Average PTA values for normal topography ectasia (45), low-suspect ectasia (39), high-suspect ectasia (36), low-suspect control (32), and high-suspect control (29) were significantly different from one another in all comparisons (P < .003) except high-and low-suspect ectasia groups (P = .033), and presented the highest discriminative capability of all variables evaluated. Age was only significantly different between the high-suspect ectasia and normal topography ectasia groups, and CCT was not significantly different between any groups. Stepwise logistic regression revealed the PTA as the most significant independent variable (P < .0001), with RSB the next most significant parameter. CONCLUSIONS: There remains a significant correlation between PTA values and ectasia risk after LASIK, even in eyes with suspicious corneal topography. Less tissue alteration, or a lower PTA value, was necessary to induce ectasia in eyes with more remarkable signs of topographic abnormality, and PTA provided better discriminative capabilities than RSB for all study populations. |
Appears in Collections: | Artigos e Materiais de Revistas Científicas - FM/MOF Artigos e Materiais de Revistas Científicas - HC/ICHC Artigos e Materiais de Revistas Científicas - LIM/33 |
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