Can higher end tonometers be used interchangeably in routine clinical practice?

Area of Science:

• Ophthalmology
• Glaucoma Management
• Ophthalmic Instrumentation

Background:

• Accurate intraocular pressure (IOP) measurement is critical for glaucoma management.
• Several instruments exist for IOP assessment, raising questions about their interchangeability.
• Understanding the agreement between different tonometers is essential for clinical practice.

Purpose of the Study:

• To evaluate the agreement in intraocular pressure (IOP) measurements among noncontact tonometer (NCT), rebound tonometer (RBT), Goldmann applanation tonometer (GAT), and dynamic contour tonometer (DCT).
• To determine if IOP measurements from newer tonometers are interchangeable with the Goldmann applanation tonometer (GAT), considered the gold standard.

Main Methods:

• A study involving 499 eyes from 250 patients over 24 months.
• Intraocular pressure (IOP) was measured sequentially using NCT, RBT, GAT, and DCT.
• Bland-Altman plots were utilized to assess agreement, with GAT serving as the reference standard.

Main Results:

• The mean IOP readings across all devices (NCT, RBT, GAT, DCT) were similar, approximately 15.9-16.0 mm Hg.
• Limits of agreement between GAT and DCT, NCT, and RBT were found to be ±5.2 to ±5.4 mm Hg.
• While a strong correlation existed, the calculated limits of agreement were deemed clinically unacceptable.

Conclusions:

• Newer tonometers show a strong correlation with the Goldmann applanation tonometer (GAT).
• However, the limits of agreement between these devices are clinically unacceptable for interchangeable use.
• Consistent use of a single tonometer per patient during follow-up visits is recommended in glaucoma clinics.