[Clinical value of new tonometers]

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Medical Instrumentation

Background:

• Accurate intraocular pressure (IOP) measurement is crucial for diagnosing and managing glaucoma.
• Various tonometry devices exist, each with differing principles and reported accuracy.
• Comparing the performance of different tonometers is essential for clinical decision-making.

Purpose of the Study:

• To evaluate and compare the accuracy and precision of three different tonometers against a standard hand-held applanation tonometer (HAT).
• To determine the suitability of Mackay-Marg and non-contact tonometers (NCTs) for clinical and scientific applications.

Main Methods:

• A clinical study involving 99 patients was conducted.
• Four tonometers were tested: a hand-held applanation tonometer (HAT), a Mackay-Marg type tonometer, and two non-contact tonometers (NCT A and NCT B).
• Two physicians performed six randomized measurements on both eyes of each patient, with a 3-minute interval between measurements on the same eye.

Main Results:

• The hand-held applanation tonometer (HAT) demonstrated good precision (r = 0.985, SD = 1.66 mmHg).
• The Mackay-Marg type tonometer and NCTs showed significantly lower precision in repetitive measurements (r = 0.85 to 0.91, SD = 2.93 to 3.5 mmHg).
• Accuracy comparisons revealed moderate correlations between the Mackay-Marg/NCTs and HAT (r = 0.84 to 0.89, SD = 3.26 to 4.55 mmHg), indicating significant deviations.

Conclusions:

• The Mackay-Marg type tonometer and the two non-contact tonometers tested exhibit insufficient accuracy and precision.
• These devices are deemed unsuitable for reliable clinical and scientific use in IOP measurement.
• The hand-held applanation tonometer remains a more dependable option based on this study's findings.