Corneal Deformation Parameters Provided by the Corvis-ST Pachy-Tonometer in Healthy Subjects and Glaucoma Patients.

Abstract

PURPOSE:

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.

MATERIALS AND METHODS:

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.

RESULTS:

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 (P<0.05). CDPs significantly differed between glaucoma patients and controls (P<0.05). GAT and Corvis-ST IOP was related to CCT (P<0.05) and CDPs (P<0.001).

CONCLUSIONS:

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.

• Authors: Maria L Salvetat, Marco Zeppieri, Claudia Tosoni, Mirella Felletti, Leonardo Grasso, Paolo Brusini
• Journal: Journal of glaucoma (J Glaucoma) 2015 Oct-Nov Vol. 24 Issue 8 Pg. 568-74 ISSN: 1536-481X [Electronic] United States
• PMID: 25318572 (Publication Type: Journal Article, Observational Study, Randomized Controlled Trial)

Chemical References

• Antihypertensive Agents

Topics

• Adult
• Aged
• Antihypertensive Agents (therapeutic use)
• Biomechanical Phenomena
• Cornea (physiopathology)
• Corneal Pachymetry
• Elasticity (physiology)
• Female
• Glaucoma, Open-Angle (drug therapy, physiopathology)
• Healthy Volunteers
• Humans
• Intraocular Pressure (physiology)
• Male
• Middle Aged
• Prospective Studies
• Tonometry, Ocular (methods)