Multicentre study: reliability and repeatability of Scheimpflug system measurement in keratoconus

Area of Science:

• Ophthalmology
• Corneal Imaging
• Refractive Surgery

Background:

• Keratoconus diagnosis and monitoring are crucial for preserving vision.
• Accurate and repeatable measurements are essential for effective patient management.
• The Pentacam HR is a widely used device for corneal tomography.

Purpose of the Study:

• To evaluate the repeatability and reliability of key tomographic parameters for keratoconus characterization using the Pentacam HR.
• To assess the impact of keratoconus severity on measurement repeatability.

Main Methods:

• Analysis of 230 eyes from 158 keratoconus patients.
• Five consecutive corneal tomography examinations per eye using Pentacam HR.
• Classification of eyes into three grades based on maximum posterior elevation (max_BFS_post).
• Calculation of intraclass correlation coefficients (ICCs) and repeatability limits for tomographic and aberrometric parameters.

Main Results:

• Excellent ICCs (0.9) were observed for all parameters, indicating high reliability.
• Repeatability limits varied: >0.5D for power, 20° for astigmatism axis, 10µm for thinnest cornea, >0.1µm for aberrometry, and >15° for coma axis.
• Repeatability generally increased with keratoconus severity, except for the coma axis.

Conclusions:

• The Pentacam HR demonstrates high reliability, supporting its use in keratoconus diagnosis.
• Repeatability limits highlight the need for updated criteria for monitoring keratoconus progression.
• Future monitoring strategies should incorporate the practical measurement capabilities of the Pentacam HR.