New Tonopen XL: comparison with the Goldmann tonometer

Area of Science:

• Ophthalmology
• Medical Devices
• Tonometry

Background:

• Intraocular pressure (IOP) measurement is crucial for diagnosing and managing glaucoma.
• Goldmann applanation tonometry is the gold standard, but newer devices aim for improved portability and ease of use.

Purpose of the Study:

• To compare intraocular pressure (IOP) measurements between the Goldmann tonometer and the new Tonopen XL.
• To evaluate the accuracy and agreement of the Tonopen XL against the Goldmann tonometer.

Main Methods:

• 104 patients' IOPs were measured using both Goldmann and Tonopen XL tonometers.
• Four observers performed measurements, with varied sequences of device use.
• Statistical analyses included paired t-tests, Pearson's r, Wilcoxon matched-pair tests, and Spearman coefficients.

Main Results:

• A statistically significant difference and correlation were found between Goldmann and Tonopen XL IOP readings (p < 0.0001 and p < 0.001).
• Tonopen XL measurements were lower than Goldmann values for IOPs exceeding 20 mmHg, a statistically significant difference.
• No significant difference in measurement discrepancies was observed across most observers, though observer B showed a significant difference.

Conclusions:

• The Tonopen XL demonstrates good precision for IOP screening, achieving similar results to the Goldmann tonometer in 62% of cases.
• Similar to previous models, the Tonopen XL is slightly less accurate for extreme IOP values compared to the Goldmann tonometer.
• Despite minor inaccuracies with extreme values, the Tonopen XL's precision is adequate for effective screening purposes.