Agreement between spectral-domain and time-domain OCT for measuring RNFL thickness

Area of Science:

• Ophthalmology
• Medical Imaging
• Glaucoma Research

Background:

• Retinal nerve fibre layer (RNFL) thickness is a key indicator in glaucoma diagnosis.
• Assessing RNFL thickness requires reliable and reproducible imaging techniques.
• Comparing different optical coherence tomography (OCT) technologies is crucial for clinical practice.

Purpose of the Study:

• To evaluate the reproducibility of spectral-domain OCT (SD-OCT) for RNFL measurements.
• To assess the agreement between SD-OCT and time-domain OCT (TD-OCT) RNFL measurements.

Main Methods:

• Acquired SD-OCT and TD-OCT scans from healthy participants and glaucoma patients.
• Evaluated SD-OCT reproducibility using within-subject standard deviation, coefficient of variation, and intraclass correlation coefficient.
• Assessed agreement between SD-OCT and TD-OCT using correlation and Bland-Altman plots.

Main Results:

• SD-OCT demonstrated excellent reproducibility for RNFL thickness in both healthy and glaucoma patient groups.
• Strong correlations were observed between RNFL parameters measured by SD-OCT, especially for average RNFL thickness.
• Bland-Altman analysis revealed good agreement between SD-OCT and TD-OCT, though TD-OCT yielded thicker RNFL measurements.

Conclusions:

• SD-OCT is a highly reproducible method for measuring RNFL thickness.
• While there is good agreement, SD-OCT and TD-OCT measurements are not interchangeable due to systematic differences.
• Clinicians should be aware of the differences when interpreting RNFL data from different OCT devices.