Comparability and repeatability of pachymetry in keratoconus using four noncontact techniques.

Area of Science:

• Ophthalmology
• Corneal Imaging
• Keratoconus Research

Background:

• Accurate central corneal thickness (CCT) measurement is crucial for diagnosing and managing keratoconus.
• Noncontact pachymetry devices are widely used, but their agreement in keratoconus eyes requires evaluation.

Purpose of the Study:

• To compare the repeatability of CCT measurements using four noncontact pachymetry instruments.
• To assess interdevice agreement and correlation for CCT measurements in keratoconus patients.

Main Methods:

• CCT was measured in 50 eyes of 25 keratoconus patients using swept source OCT (SS-OCT), Pentacam (Scheimpflug), Orbscan IIz (scanning slit), and hand-held SD-OCT (HHSD-OCT).
• Test-retest variability, measurement correlation, and interdevice agreement were analyzed.

Main Results:

• All four devices demonstrated good correlation (r > 0.9, P < 0.001) in CCT measurements.
• Mean CCT values ranged from 447 ± 42 mm (Pentacam) to 462 ± 41 mm (HHSD-OCT).
• HHSD-OCT overestimated CCT, and significant numerical differences were observed between all device pairs, despite good correlation.

Conclusions:

• While CCT measurements from the four devices correlate well, the numerical discrepancies limit their interchangeable use in clinical practice.
• Further research is needed to establish the clinical utility of each device for specific keratoconus management decisions.