Imaging of Pediatric Retinal Pathology with Long Working Distance Swept Source Optical Coherence Tomography

Abstract

Purpose : Conventional optical coherence tomography (OCT) systems have working distances of about 25 mm, and require a chin rest to immobilize the patients. However, imaging young children is challenging due to their lack of attention and inherent fear of large objects close to their face. In this work, we describe a novel 2f OCT system with a long working distance (from the last optical element to the subject’s eye) of 348mm, and demonstrate its utility for adult and pediatric subjects with retinal pathology.

Methods : An optical schematic of the novel 2f scanning configuration of the OCT sample arm is shown in Fig.1 (a). The optical design and performance of the system was detailed previously (Invest. Ophthalmol. Vis. Sci. 2015; 56(7):4094).The objective lens L₂ with f=250mm, results in a working distance of 348mm. An iris camera was used to facilitate subject alignment by placement of the subject’s iris centered on a dot on the camera images. Images were captured either with (mounted on a slit lamp base, to align with the system) or without a chin rest (gently holding the subject’s head) supporting the subject [Fig 1 (b)]. B-scans, volumetric images of the fovea and optic nerve were obtained.

Results : 26 adult subjects (10 with and 16 without retinal disease) and 4 children aged 13-17 (2 with and 2 without retinal disease) were imaged under a Duke Medical Center IRB protocol. Representative images from both adults and children are shown in Fig.2.

Conclusions : We have demonstrated for the first time the use of a novel 2f OCT system with a long working distance of 348mm for imaging adults and children with and without retinal pathology and with and without pupil dilation. This optical design may have significant advantages for imaging patients who are unable to cooperate with a system near their face.

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

 

Fig.1 A: Schematic of the OCT sample arm and subject alignment system. L1, L2: custom lenses; DM: dichroic mirror; G: galvanometer mirror pair; M: first surface mirror; LCD: LCD fixation target monitor; Cam: iris camera; B: 13 year old girl being aligned without a chin rest to the OCT system

 

Fig.2 (a) B-scan from an undilated 14 year old child, and (b) corresponding volumetric foveal scan. (c) B-scan from a 79 year old dilated adult subject with RPE elevation. (d) B-scan from a dialated 16 year old child with juvenile idiopathic arthritis and bilateral optic nerve cupping. All B-scans 10x averaged.