Quantitative Ciliary Body Imaging Using Image-Registered Swept-Source AS-OCT and Ultrasound Biomicroscopy

Area of Science:

• Ophthalmology
• Biomedical Imaging
• Anatomical Measurement

Background:

• Accurate measurement of ciliary body (CB) parameters is crucial for understanding ocular physiology and managing various eye conditions.
• Traditional methods like ultrasound biomicroscopy (UBM) are contact-based, potentially causing discomfort and introducing variability.
• Advancements in non-contact imaging, such as swept-source anterior segment optical coherence tomography (AS-OCT), offer potential alternatives for CB assessment.

Purpose of the Study:

• To evaluate the inter- and intra-device agreement of ciliary body (CB) biometric parameters obtained using image-registered swept-source AS-OCT (ANTERION) and ultrasound biomicroscopy (UBM; Insight 100).
• To compare the consistency and repeatability of CB measurements between two distinct imaging modalities.

Main Methods:

• Prospective enrollment of patients undergoing anterior segment imaging.
• Acquisition of horizontal scans using standardized illumination; one eye per participant was randomly selected.
• Manual measurement of maximum ciliary muscle thickness (CMTMAX), maximum CB thickness (CBTMAX), sulcus-to-sulcus (STS) distance, and scleral spur-to-scleral spur (SSS) distance. Inter- and intra-device agreement assessed using intraclass correlation coefficients (ICCs), linear regression, and Bland-Altman analysis.

Main Results:

• Seventy-eight eyes were analyzed, revealing good to excellent inter-device agreement between AS-OCT and UBM (ICC = 0.60–0.85).
• Mean absolute inter-device differences ranged from 0.18 ± 0.16 mm (STS) to 57.6 ± 36.6 µm (CBTMAX), with relative differences below 6%.
• Intra-device repeatability was excellent for both systems (ICC = 0.78–0.94). Greater baseline CBTMAX was associated with inter-device differences in CB thickness measurements.

Conclusions:

• Image-registered AS-OCT and UBM provide largely concordant and highly repeatable ciliary body (CB) measurements.
• Systematic inter-device differences exist, indicating that AS-OCT and UBM cannot be considered fully interchangeable for quantitative CB assessment.
• Modern AS-OCT represents a viable, non-contact alternative to UBM for quantitative CB analysis.