Results of a clinical study show that a modified correcting applanation tonometry surface (CATS) prism (CATS Tonometer Prism, Intuor Technologies) reduces measurement errors due to corneal biomechanical parameters and improves the accuracy of IOP measurements compared with a standard Goldmann applanation tonometer (GAT) prism, said Sean McCafferty, MD.
The CATS prism, which received 510(k) clearance in March 2018, fits onto any existing Goldmann or Perkins tonometer without need for recalibration or alteration in measurement technique or interpretation.
Designed to overcome IOP measurement errors due to patient variability in corneal thickness, rigidity, curvature, and tear film adhesion force, the CATS prism differs from a standard GAT prism by its shaped contact surface, which has a central concave region surrounded by an annular convexity.
Dr. McCafferty compared the measurement accuracy of the GAT and CATS prisms and the effects of corneal thickness and biomechanics on the data acquired in a study that included 58 eyes undergoing cataract surgery. Manometrically modulated and maintained IOP measured with an intracameral pressure transducer was used as the reference.