Corneal Deformation Parameters Provided by the Corvis-ST Pachy-Tonometer in Healthy Subjects and Glaucoma Patients. Issue 8 (October 2015)

• Record Type: Journal Article
• Authors: Salvetat, Maria L.; Zeppieri, Marco; Tosoni, Claudia; Felletti, Mirella; Grasso, Leonardo; Brusini, Paolo
• Is Part Of: Journal of glaucoma. Volume 24:Issue 8(2015:Oct./Nov.)
• Publication Date: 2015-10
• Subjects: Glaucoma -- Periodicals; 617.741005
• DOI: 10.1097/IJG.0000000000000133
• Languages: English
• ISSNs: 1057-0829

Abstract

<abstract> <title> <x xml:space="preserve">Abstract</x> </title> <sec> <title>Purpose:</title> <p>To evaluate precision and accuracy of Corvis-ST, a new noncontact tonometer equipped with a high-speed Scheimpflug technology, which measures intraocular pressure (IOP), central corneal thickness (CCT), and corneal deformation parameters (CDPs). Relationships among IOP, CCT, and CDPs were also assessed.</p> </sec> <sec> <title>Materials and Methods:</title> <p>This prospective, randomized study included 1 eye of 164 subjects (79 controls and 85 glaucoma patients), which underwent IOP measurements taken 3 times with Goldmann applanation tonometry (GAT) and Corvis-ST in random order. Precision was evaluated using intraclass correlation coefficients. Intermethod agreement was assessed using Bland-Altman method. Relationships amongst IOP, CCT and CDPs were evaluated using linear regression analysis.</p> </sec> <sec> <title>Results:</title> <p>Corvis-ST intraclass correlation coefficients ranged between 0.95 and 0.99 for IOP and CCT; between 0.17 and 0.97 for CDPs. Mean (GAT−Corvis-ST) IOP was 1.4±2.7 mm Hg, which appeared related to IOP and CDPs (<italic>P</italic><0.05). CDPs significantly differed between glaucoma patients and controls (<italic>P</italic><0.05). GAT and Corvis-ST IOP was related to CCT (<italic>P</italic><0.05) and CDPs (<italic>P</italic><0.001).</p> </sec> <sec> <title>Conclusions:</title> <p>Corvis-ST precision was excellent for IOP and CCT; moderate for CDPs. Corvis-ST underestimated GAT IOP, especially at higher IOP and at lower corneal deformability levels. GAT and Corvis-ST IOP increased in thicker and less deformable corneas. Glaucoma patients showed significantly less deformable corneas than controls.</p> </sec> </abstract>