Evaluation of Corvis ST tonometer with the updated software in glaucoma practice

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Corneal Biomechanics

Background:

• Intraocular pressure (IOP) measurement is crucial for glaucoma diagnosis and management.
• Accurate IOP assessment can be influenced by central corneal thickness (CCT).
• The Corvis ST tonometer offers biomechanically corrected IOP (b-IOP) and corneal deformation parameters.

Purpose of the Study:

• To evaluate the agreement between the updated Corvis ST tonometer and traditional methods (Goldmann applanation tonometry - GAT, optical-based corneal pachymetry - OB-CCT).
• To assess b-IOP and Corvis-derived CCT (Corvis-CCT) against GAT IOP and OB-CCT.
• To examine differences in Corvis ST corneal deformation parameters among controls, ocular hypertension (OHT), and primary open-angle glaucoma (POAG) patients.

Main Methods:

• Prospective study including 80 eyes from 80 participants (POAG, OHT, and controls).
• Measurements included GAT IOP, OB-CCT, and updated Corvis ST tonometer readings.
• Bland-Altman analysis was used to assess agreement between measurement methods.

Main Results:

• Good correlation was found between GAT IOP and b-IOP (Spearman's rho=0.767, P<0.001).
• b-IOP showed no significant correlation with OB-CCT (Spearman's rho=-0.13, P=0.917).
• Corvis-CCT correlated well with OB-CCT (Spearman's rho=0.900, P<0.001).
• POAG eyes exhibited a significantly reduced applanation time 2 compared to controls after adjustment.

Conclusions:

• The updated Corvis ST tonometer provides b-IOP and CCT measurements that correlate well with GAT IOP and OB-CCT.
• b-IOP's independence from CCT is advantageous for managing thick or thin corneas.
• Altered corneal viscoelasticity in POAG patients may be reflected by shorter applanation times measured by the Corvis ST.