Characterization of Long Working Distance Optical Coherence Tomography for Imaging of Pediatric Retinal Pathology

Abstract

Purpose: We determined the feasibility of fovea and optic nerve head imaging with a long working distance (LWD) swept source optical coherence tomography (OCT) prototype in adults, teenagers, and young children.

Methods: A prototype swept source OCT system with a LWD (defined as distance from the last optical element of the imaging system to the eye) of 350 mm with custom fixation targets was developed to facilitate imaging of children. Imaging was performed in 49 participants from three age groups: 26 adults, 16 children 13 to 18 years old (teenagers), and seven children under 6 years old (young children) under an approved institutional review board protocol. The imaging goal was to acquire high quality scans of the fovea and optic nerve in each eye in the shortest time possible. OCT B-scans and volumes of the fovea and optic nerve head of each eligible eye were captured and graded based on four categories (lateral and axial centration, contrast, and resolution) and on ability to determine presence or absence of pathology.

Results: LWD-OCT imaging was successful in 88 of 94 eligible eyes, including seven of 10 eyes of young children. Of the successfully acquired OCT images, 83% of B-scan and volumetric images, including 86% from young children, were graded as high-quality scans. Pathology was observed in high-quality OCT images.

Conclusions: The prototype LWD-OCT system achieved high quality retinal imaging of adults, teenagers, and some young children with and without pathology with reasonable alignment time.

Translational relevance: The LWD-OCT system can facilitate imaging in children.

Keywords: long working distance; optical coherence tomography; pediatric imaging; retinal imaging.

Figures

Figure 1

LWD OCT prototype sample arm. The distance between the dichroic mirror and the participant's eye is approximately 35 cm.

Figure 2

Demonstrations of the typical positioning of older and younger children with the imaging system. (a) A 9-year-old child aligned with the system by the operator. (b) A 2-year-old child seated in the parent's lap and aligned by the parent. (All photographs with parental permission.) The green dot on the pupil camera image indicates the location of the OCT beam.

Figure 3

(a) Volumetric image centered on the fovea of a 6-year-old child before motion correction. (b) Single B-scan at the center of the fovea with a segmentation line (red) at the top of the IS/OS band. (c) The same volumetric image after motion correction.

Figure 4

Representative SSOCT images acquired from a teenager and young child with and without pathology are illustrated and obtained with the prototype system. (a) Ten averaged B-scans of a healthy 6-year-old child. (b) Volume of the fovea of a healthy 2-year-old child. (c, d) Ten averaged B-scans and volume of optic nerve of a healthy 6-year-old child. (e, f) Ten averaged B-scans and the cross section of volume of a 5-year-old child with retinoschisis. (g, h) Ten averaged B-scans and volume of a 16-year-old child with optic nerve head elevation. All B-scans and volumetric images here were graded as high-quality scans.

Figure 5

Boxplot of image grading scores of three age groups in the study, and results of the Wilcoxon rank sum test between every pair of two age groups. Outliers are defined as the scores larger than 1.5 times the interquartile range of the box.

Figure 6

Alignment time of 38 eyes of adults (red dots), six eyes of teenagers (green circles), and seven eyes of young children (blue diamonds).

Figure 7

Representative “acceptable” (score between 5 and 6) and “unacceptable” (score under 5) quality images from participants with and without pathology are illustrated and obtained with the prototype system. (a) Seven averaged B-scans of fovea of a 21-month-old child with possible cysts or split in the inner nuclear layer. The total score is 5 (contrast, 1; resolution, 1; lateral centration, 2; vertical centration, 1). (b) Ten averaged B-scans of fovea of a 16-year-old teenager with +4.25 D astigmatism. The total score is 6 (contrast, 1; resolution, 1; lateral centration, 2; vertical centration, 2). (c) Ten averaged B-scans of optic nerve of a 17-year-old teenager with congenital glaucoma (severe stage) with eccentric fixation. The total score is 6 (contrast, 1; resolution, 1; lateral centration, 2; vertical centration, 2). (d) Ten averaged B-scans of fovea of a 51-year-old adult. The total score is 4 (contrast, 1; resolution, 1; lateral centration, 0; vertical centration, 2).