Reliability coefficients of three corneal pachymeters

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Optometry

Background:

• Accurate corneal thickness measurement is crucial for diagnosing and managing various ocular conditions.
• Ultrasound pachymetry and specular microscopy are common methods for assessing corneal thickness.
• Evaluating the performance of new and existing pachymetry devices is essential for clinical practice.

Purpose of the Study:

• To compare the accuracy and reproducibility of the Pach-Pen handheld ultrasound pachymeter against the DGH 1000 ultrasound pachymeter and the Pro-Cem 4 specular microscope.
• To assess the performance of these instruments in measuring corneal thickness at central and peripheral locations.
• To determine the reliability of each instrument for clinical use.

Main Methods:

• A comparative study involving 18 healthy human subjects.
• Corneal thickness was measured using the Pach-Pen, DGH 1000, and Pro-Cem 4.
• Five repeated measurements were taken at five corneal locations (central and four peripheral) for each instrument.
• Accuracy of ultrasound pachymeters was validated using test blocks of known thickness.

Main Results:

• The Pach-Pen exhibited higher accuracy than the DGH 1000, with measurements closer to the true thickness.
• All three instruments demonstrated excellent intraobserver reproducibility (reliability coefficients >90%).
• Consistency in mean thickness measurements was highest at the center of the cornea for all devices.

Conclusions:

• The Pach-Pen handheld ultrasound pachymeter is a more accurate device for measuring corneal thickness compared to the DGH 1000.
• All evaluated instruments offer high intraobserver reproducibility, crucial for reliable clinical assessments.
• The findings support the clinical utility of the Pach-Pen for accurate corneal thickness measurements.