圆锥角膜偏心病理比中心病理表现出更强的生物力学反应

IF 3.2 Q1 OPHTHALMOLOGY

Ophthalmology science Pub Date : 2024-12-20 DOI:10.1016/j.xops.2024.100682

Cameron D. Bruner BS, MD , Ashraf M. Mahmoud BS , Cynthia J. Roberts PhD

{"title":"圆锥角膜偏心病理比中心病理表现出更强的生物力学反应","authors":"Cameron D. Bruner BS, MD , Ashraf M. Mahmoud BS , Cynthia J. Roberts PhD","doi":"10.1016/j.xops.2024.100682","DOIUrl":null,"url":null,"abstract":"<div><h3>Purpose</h3><div>To investigate the difference in biomechanical response metrics between central and eccentric pathology and compare axial vs. tangential curvature, as well as zonal vs. single-point values.</div></div><div><h3>Design</h3><div>Prospective, observational, cross-sectional study.</div></div><div><h3>Participants</h3><div>The study included 67 eyes of 41 subjects diagnosed with keratoconus (KCN).</div></div><div><h3>Methods</h3><div>Pentacam tomography and Corvis ST examinations were acquired, and disease severity was defined by maximum curvature, comparing single point of maximum anterior axial curvature (Kmax) vs. magnitude of surrounding 2 mm zonal value (ZKmax) on axial maps, vs. magnitude of steepest 2 mm zone on axial (CSpot_Axi) and tangential (CSpot_Tan) maps located by Cone Location and Magnitude Index (CLMI). Distance between the corneal center and Kmax (Kmax_dist) was compared to radial distance with CLMI (CRad_Axi and CRad_Tan). Single-point Kmax, ZKmax, and CLMI-derived zones were compared with biomechanical metrics via regression analyses, including stiffness parameter at first applanation (SP-A1), deformation amplitude ratio at 2 mm (DA Ratio), integrated inverse radius (IIR), and stress–strain index (SSI). Measurements were analyzed using paired <em>t</em> tests, with <em>t</em> tests between central and eccentric disease, and a significance threshold, <em>P</em> < 0.05.</div></div><div><h3>Main Outcome Measures</h3><div>Maximum curvature using axial vs. tangential curvature, zonal vs. single-point curvature, and corneal stiffness metrics compared with cone location.</div></div><div><h3>Results</h3><div>Significantly greater central pathology was found using tangential (58 central and 9 eccentric) vs. axial curvature (28 central and 39 eccentric). ZKmax was significantly different than CSpot_Axi and CSpot_Tan (<em>P</em> < 0.0001). CRad_Axi (1.53 ± 0.41 mm) was significantly greater (<em>P</em> < 0.001) than Kmax_dist (1.33 ± 0.56 mm) and CRad_Tan (0.99 ± 0.34 mm). Kmax (56.09 ± 8.99 diopter [D]) was significantly greater than ZKmax (51.81 ± 7.50 D). Regressions for ZKmax, CSpot_Axi, and CSpot_Tan were significantly negative to SP-A1, stiffness parameter at highest concavity, and SSI, whereas significantly positive to DA Ratio and IIR. Regressions for Kmax_dist, CRad_Axi, and CRad_Tan had significantly positive relationships to SSI and significantly negative relationships to DA Ratio and IIR.</div></div><div><h3>Conclusions</h3><div>Central pathology has greater frequency with tangential than axial curvature. Corneal stiffness increases as the distance of the cone from the center increases, consistent with the focal nature of KCN. Central stiffness decreases as cone curvature (disease severity) increases. Recommendation is to use zonal values with tangential curvature to evaluate the location of the greatest curvature and changes in curvature over time.</div></div><div><h3>Financial Disclosure(s)</h3><div>Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.</div></div>","PeriodicalId":74363,"journal":{"name":"Ophthalmology science","volume":"5 3","pages":"Article 100682"},"PeriodicalIF":3.2000,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Eccentric Pathology in Keratoconus Exhibits Stiffer Biomechanical Response than Central Pathology\",\"authors\":\"Cameron D. Bruner BS, MD , Ashraf M. Mahmoud BS , Cynthia J. Roberts PhD\",\"doi\":\"10.1016/j.xops.2024.100682\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><h3>Purpose</h3><div>To investigate the difference in biomechanical response metrics between central and eccentric pathology and compare axial vs. tangential curvature, as well as zonal vs. single-point values.</div></div><div><h3>Design</h3><div>Prospective, observational, cross-sectional study.</div></div><div><h3>Participants</h3><div>The study included 67 eyes of 41 subjects diagnosed with keratoconus (KCN).</div></div><div><h3>Methods</h3><div>Pentacam tomography and Corvis ST examinations were acquired, and disease severity was defined by maximum curvature, comparing single point of maximum anterior axial curvature (Kmax) vs. magnitude of surrounding 2 mm zonal value (ZKmax) on axial maps, vs. magnitude of steepest 2 mm zone on axial (CSpot_Axi) and tangential (CSpot_Tan) maps located by Cone Location and Magnitude Index (CLMI). Distance between the corneal center and Kmax (Kmax_dist) was compared to radial distance with CLMI (CRad_Axi and CRad_Tan). Single-point Kmax, ZKmax, and CLMI-derived zones were compared with biomechanical metrics via regression analyses, including stiffness parameter at first applanation (SP-A1), deformation amplitude ratio at 2 mm (DA Ratio), integrated inverse radius (IIR), and stress–strain index (SSI). Measurements were analyzed using paired <em>t</em> tests, with <em>t</em> tests between central and eccentric disease, and a significance threshold, <em>P</em> < 0.05.</div></div><div><h3>Main Outcome Measures</h3><div>Maximum curvature using axial vs. tangential curvature, zonal vs. single-point curvature, and corneal stiffness metrics compared with cone location.</div></div><div><h3>Results</h3><div>Significantly greater central pathology was found using tangential (58 central and 9 eccentric) vs. axial curvature (28 central and 39 eccentric). ZKmax was significantly different than CSpot_Axi and CSpot_Tan (<em>P</em> < 0.0001). CRad_Axi (1.53 ± 0.41 mm) was significantly greater (<em>P</em> < 0.001) than Kmax_dist (1.33 ± 0.56 mm) and CRad_Tan (0.99 ± 0.34 mm). Kmax (56.09 ± 8.99 diopter [D]) was significantly greater than ZKmax (51.81 ± 7.50 D). Regressions for ZKmax, CSpot_Axi, and CSpot_Tan were significantly negative to SP-A1, stiffness parameter at highest concavity, and SSI, whereas significantly positive to DA Ratio and IIR. Regressions for Kmax_dist, CRad_Axi, and CRad_Tan had significantly positive relationships to SSI and significantly negative relationships to DA Ratio and IIR.</div></div><div><h3>Conclusions</h3><div>Central pathology has greater frequency with tangential than axial curvature. Corneal stiffness increases as the distance of the cone from the center increases, consistent with the focal nature of KCN. Central stiffness decreases as cone curvature (disease severity) increases. Recommendation is to use zonal values with tangential curvature to evaluate the location of the greatest curvature and changes in curvature over time.</div></div><div><h3>Financial Disclosure(s)</h3><div>Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.</div></div>\",\"PeriodicalId\":74363,\"journal\":{\"name\":\"Ophthalmology science\",\"volume\":\"5 3\",\"pages\":\"Article 100682\"},\"PeriodicalIF\":3.2000,\"publicationDate\":\"2024-12-20\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Ophthalmology science\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S2666914524002185\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"OPHTHALMOLOGY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Ophthalmology science","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2666914524002185","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"OPHTHALMOLOGY","Score":null,"Total":0}

引用次数: 0

摘要

目的探讨中枢性和偏心性病理在生物力学反应指标上的差异，比较轴向曲率和切向曲率，以及区向曲率和单点曲率的差异。设计前瞻性、观察性、横断面研究。该研究包括41名被诊断为圆锥角膜（KCN）的受试者的67只眼睛。方法获得spentacam断层扫描和Corvis ST检查，通过最大曲率来定义疾病的严重程度，比较轴向图上最大前轴曲率单点（Kmax）与周围2mm区域值（ZKmax）的大小，以及轴向图（CSpot_Axi）和切向图（CSpot_Tan）上最陡峭2mm区域的大小，通过Cone Location和magnitude Index （CLMI）定位。比较角膜中心到Kmax的距离（Kmax_dist）与CLMI的径向距离（CRad_Axi和CRad_Tan）。通过回归分析，将单点Kmax、ZKmax和clmi衍生区域与生物力学指标进行比较，包括首次压平时刚度参数（SP-A1）、2mm变形幅度比（DA ratio）、积分反半径（IIR）和应力-应变指数（SSI）。测量结果采用配对t检验进行分析，采用中枢性和偏心性疾病之间的t检验和显著性阈值P <；0.05.主要观察指标：轴向曲率与切向曲率的最大曲率，区域曲率与单点曲率的最大曲率，以及与锥体位置相比的角膜刚度指标。结果切向（中心58例，偏心9例）比轴向（中心28例，偏心39例）有更大的中心病变。ZKmax与CSpot_Axi和CSpot_Tan差异显著(P <；0.0001)。CRad_Axi（1.53±0.41 mm）显著增高(P <；0.001)，高于Kmax_dist（1.33±0.56 mm）和CRad_Tan（0.99±0.34 mm）。Kmax（56.09±8.99屈光度[D]）显著大于ZKmax(51.81±7.50 D)， ZKmax、CSpot_Axi和CSpot_Tan与SP-A1、最高凹度刚度参数和SSI呈显著负相关，而与DA Ratio和IIR呈显著正相关。Kmax_dist、CRad_Axi和CRad_Tan回归与SSI呈显著正相关，与DA Ratio和IIR呈显著负相关。结论中枢性病变以切向曲率多于轴向曲率。角膜硬度随角膜锥距中心距离的增加而增加，这与KCN的焦性一致。中心刚度随着锥体曲率（疾病严重程度）的增加而降低。建议使用带切向曲率的分区值来评估最大曲率的位置和曲率随时间的变化。财务披露专有或商业披露可在本文末尾的脚注和披露中找到。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

查看原文本刊更多论文

Eccentric Pathology in Keratoconus Exhibits Stiffer Biomechanical Response than Central Pathology

Purpose

To investigate the difference in biomechanical response metrics between central and eccentric pathology and compare axial vs. tangential curvature, as well as zonal vs. single-point values.

Design

Prospective, observational, cross-sectional study.

Participants

The study included 67 eyes of 41 subjects diagnosed with keratoconus (KCN).

Methods

Pentacam tomography and Corvis ST examinations were acquired, and disease severity was defined by maximum curvature, comparing single point of maximum anterior axial curvature (Kmax) vs. magnitude of surrounding 2 mm zonal value (ZKmax) on axial maps, vs. magnitude of steepest 2 mm zone on axial (CSpot_Axi) and tangential (CSpot_Tan) maps located by Cone Location and Magnitude Index (CLMI). Distance between the corneal center and Kmax (Kmax_dist) was compared to radial distance with CLMI (CRad_Axi and CRad_Tan). Single-point Kmax, ZKmax, and CLMI-derived zones were compared with biomechanical metrics via regression analyses, including stiffness parameter at first applanation (SP-A1), deformation amplitude ratio at 2 mm (DA Ratio), integrated inverse radius (IIR), and stress–strain index (SSI). Measurements were analyzed using paired t tests, with t tests between central and eccentric disease, and a significance threshold, P < 0.05.

Main Outcome Measures

Maximum curvature using axial vs. tangential curvature, zonal vs. single-point curvature, and corneal stiffness metrics compared with cone location.

Results

Significantly greater central pathology was found using tangential (58 central and 9 eccentric) vs. axial curvature (28 central and 39 eccentric). ZKmax was significantly different than CSpot_Axi and CSpot_Tan (P < 0.0001). CRad_Axi (1.53 ± 0.41 mm) was significantly greater (P < 0.001) than Kmax_dist (1.33 ± 0.56 mm) and CRad_Tan (0.99 ± 0.34 mm). Kmax (56.09 ± 8.99 diopter [D]) was significantly greater than ZKmax (51.81 ± 7.50 D). Regressions for ZKmax, CSpot_Axi, and CSpot_Tan were significantly negative to SP-A1, stiffness parameter at highest concavity, and SSI, whereas significantly positive to DA Ratio and IIR. Regressions for Kmax_dist, CRad_Axi, and CRad_Tan had significantly positive relationships to SSI and significantly negative relationships to DA Ratio and IIR.

Conclusions

Central pathology has greater frequency with tangential than axial curvature. Corneal stiffness increases as the distance of the cone from the center increases, consistent with the focal nature of KCN. Central stiffness decreases as cone curvature (disease severity) increases. Recommendation is to use zonal values with tangential curvature to evaluate the location of the greatest curvature and changes in curvature over time.