Understanding the variability of handheld spectral-domain optical coherence tomography measurements in supine infants

Abstract

Purpose: Central foveal thickness (CFT) measurements from optical coherence tomography (OCT) scans provide a precise measure of severity of pathologic changes in the fovea, progress of disease and response to treatment. Although these measures are additionally valuable to assess foveal development in infants, their reproducibility is not known. The goal of this retrospective study is to evaluate the variation and reproducibility of CFT measurements using handheld spectral-domain OCT (hh-SDOCT) in supine infants compared to conventional adult tabletop imaging.

Methods: Imaging sessions with multiple macular, volume scans in one eye were selected for analysis from two participant groups: Group 1, 25 imaging sessions from 21 preterm infants without macular edema imaged supine in the nursery using hh-SDOCT (Leica/Bioptigen Envisu C2300, RTP, NC); Group 2, 25 imaging sessions from 25 adults imaged using tabletop Bioptigen SDOCT. For each imaging session, three macular OCT volumes with acceptable image quality were selected for analysis. CFTs were measured using a customized script for automatic segmentation. An expert grader and a typical grader corrected the segmentation lines for the central foveal frame. Coefficient of variations (CV) and intraclass correlation coefficients (ICC) were calculated for graders and systems and compared to the previous literature on OCT reproducibility.

Results: CFT measurements were repeatable and reproducible for both handheld and tabletop SDOCT systems. For handheld, grader ICC (CI) and mean CV were 0.94 (0.90-0.97) and 3.8 (typical) and 0.98 (0.96-0.99) and 2.9 (expert), and for tabletop were 0.91(0.83-0.96) and 2.1 (typical) and 0.92 (0.86-0.96) and 1.9 (expert). Intergrader reproducibility of handheld and tabletop SDOCT systems were ICC(CI) 0.97 (0.95-0.98) and 0.93 (0.89-0.96) respectively, and both are comparable to previously reported reproducibility of tabletop systems.

Conclusion: Handheld SDOCT is a reproducible instrument to measure foveal thicknesses in supine infants. It can be used in clinical research to evaluate foveal changes during retinal development and pathological conditions.

Conflict of interest statement

Dr. Toth receives royalties from Alcon, for surgical technologies unrelated to this research. The authors would like to declare the following patents/patent applications associated with this research: Dr. Toth has unlicensed patents for OCT imaging and image analytic technologies. This does not alter our adherence to PLOS ONE policies on sharing data and materials. The other authors have declared that no competing interests exist.

Figures

Fig 1. Sample foveal OCT B-scans from infant and adult participant scan volumes.

The inner border of internal limiting membrane (white line) and outer border of Bruch’s membrane (purple line) were marked at the foveal center (yellow star) of foveal b-scans from three volumes for each participant: a) a preterm infant imaged using hh-SDOCT (Group 1) and b) a healthy adult imaged using tabletop SDOCT (Group 2). CFT measurements were calculated as the distance between the lines at the foveal center.

Fig 2

Box and whisker plots of coefficients of variation for a) expert grader measurements from handheld images versus tabletop images, and b) typical grader measurements from handheld images versus tabletop images (one CV outlier (19.6) is not shown for typical grader of handheld images for proper sizing of the box and whisker plot).

Fig 3

Comparison of central foveal thickness measurements between expert and typical graders for a) hh-SDOCT in preterm infants and b) tabletop SDOCT in adults. Note a greater range in foveal thicknesses in infants (~80–240 μm) than adults (~200–300 μm) was observed.