Parafoveal cone photoreceptor imaging in infants and young children using an ultra-compact SLO/OCT handheld probe

Abstract

Purpose : In vivo photoreceptor imaging has enabled numerous advancements in the understanding of retinal structure, function, and the pathogenesis of several ocular diseases. However, the complex interface of current systems capable of resolving photoreceptors precludes the imaging of small children. Here, we show that our handheld probe, weighing only 94 g, can both visualize and quantify photoreceptors in supine children. This work lays the foundation for pediatric research to improve understanding of retinal development, mal-development and early onset of diseases during the beginning stages of human growth.

Methods : The probe design permits ~7° field of view (FOV), ~8 um resolution, and 15 frames per second (fps) imaging for SLO and 40 fps for OCT. Under an IRB approved protocol, infants and children between 14 weeks and 12 years were imaged. SLO and OCT images were acquired sequentially on all subjects in a supine position either in the neonatal intensive care unit or during examination under anesthesia in the operating room. SLO images were digitally deblurred to enhance contrast.

Results : High-resolution in vivo retinal images were successfully obtained from infants and children demonstrating parafoveal cone imaging (Figure 1). Parafoveal cone densities were determined for two subjects: a 25 month old toddler (15700 cones/mm^-2 at 4.2° from fovea) and a 14 month old infant (12200 cones/mm^-2 at 10.7° from fovea).

Conclusions : Ultra-compact, handheld SLO/OCT was used to image the parafoveal cone mosaic in infants and children for the first time. Compared to adults, parafoveal cone densities were 50% higher in infants at 10.7° from fovea. This finding supports the hypothesis that cones migrate toward the fovea with age [Yuodelis et al. Vision Res. (1986)]. Further development and use of this imaging system will aid in the understanding of retinal morphology, development and early onset of pathology in the developing eye.

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

 

Imaging results from a 25 month old toddler in the operating room. A) Large FOV SLO image (~7° FOV, 20 frame average). B) Small FOV SLO image (~3° FOV, 25 frame average, located within green box in (A)) showing parafoveal cones. Cone density was quantified for the region indicated by the red box in (B). C) OCT B-scan (6° FOV, 20 frame average) near the fovea. Asterisks indicate the foveal center in (A) and (C). D) Assembled probe in handheld use. Scale bars, 1°.