Pediatric Anterior Segment Ultrasound Biomicroscopy Image Analysis: Intra and Inter-observer Agreement

Abstract

Purpose : Previous studies have validated the use of ultrasound biomicroscopy (UBM) to measure anterior segment (AS) structures in adults. This is a novel study depicting a standardized imaging and measurement protocol with reliability analysis using UBM and ImageJ software.

Methods : Patients undergoing exam under anesthesia for AS pathology (including cataract, glaucoma, and dysgenesis) were imaged using UBM. Using the trabecular-iris angle (TIA) as a landmark reference point, 40 UBM images from 20 pediatric patients’ eyes were analyzed by 4 trained observers. 46 structural parameters, some of which relied on the TIA as a landmark and others did not (TIA-dependent [TD] and non-TIA dependent [NTD], respectively), were measured in each image twice using ImageJ by the same observer. Some measurements required reference lines/measurements to be taken first and were classified as a certain degree removed from the reference (seen in Tables 1 & 2). Corresponding measurements were compared between observers. Intra-observer repeatability (IOR) and inter-observer agreement (IOA) for the measurements were determined using coefficient of variation (CV) and intra-class correlation (ICC) followed by assessment of Bland-Altman plots (BAP) for each pair of observers, respectively.

Results : For NTD parameters, non-ciliary body (CB) related measurements showed CV range 0.60-16.22% and ICC range 0.84-0.89, whereas CB-related parameters showed CV range 2.86-23.40% and ICC range 0.29-0.92. For TD parameters, parameters < 2 degrees removed from reference showed CV range 0.024-5.40% and ICC range 0.89-1.00, whereas parameters > 1 degree removed showed CV range 0.63-27.44% and ICC range 0.22-1.00. Results shown in Tables 1 & 2. BAP’s demonstrated no variation in reliability related specifically to measurements’ underlying values.

Conclusions : Preplaced landmarks yielded good IOR and IOA in quantitative assessment of AS structures that were NTD and non-CB related, or less removed from reference. NTD measurements based on CB varied greatly in IOR and IOA, suggesting protocol modifications to improve accuracy or qualitative assessment for the CB. Increasing variability in TD measurements with increasing degrees removed from the reference landmark supports use of another reference landmark to minimize variation. This study provides an assessment of reliability of AS measurements that may be applied to UBM image analysis.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.