Choroid development and feasibility of choroidal imaging in the preterm and term infants utilizing SD-OCT

Abstract

Purpose: To determine whether choroidal imaging is feasible in preterm and term infants using an 840-nm portable spectral domain optical coherence tomography (SD-OCT) system without the use of enhanced-depth imaging techniques and to assess choroidal development by comparing choroidal thickness of preterm infants, term infants, and adults.

Methods: SD-OCT images were obtained from 86 preterm infants, 59 term infants, and nine adults using a portable SD-OCT system plus nine adults using a tabletop system. An unprocessed image across the macula from one randomly selected eye of each participant was selected for determination of whether the choroidal-scleral junction (CSJ) could be visualized and for measurement of choroidal thickness.

Results: Subfoveal CSJ was visualized in 96% of young-preterm infants (imaged from 30-36 weeks postmenstrual age [PMA]); 78% of term-aged preterm infants (imaged from 37-42 weeks PMA); 49% of term infants; and 39% of adult subjects. Racial pigmentation did not affect CSJ visibility in young-preterm infants (P = 0.57). Subfoveal choroidal thickness (SFCT) in young-preterm infants, term-aged preterm infants, term infants, and adults was 176 ± 53 μm, 289 ± 92 μm, 329 ± 66 μm, and 258 ± 66 μm, respectively, and these were all statistically significantly different from one another except term-aged preterms to adults.

Conclusions: Infant choroid can be imaged with a portable SD-OCT system without enhanced depth imaging. Melanin in the RPE and choroid does not hinder outer choroidal imaging in young-preterm infants without advanced retinopathy of prematurity (ROP). In preterm infants, choroidal thickness increased with age but was thinner when compared to term infants suggesting delayed development due to ROP.

Keywords: choroid; ocular development; optical coherence tomography; retinopathy of prematurity.

Figure 1

Single, unprocessed foveal B-scans from young premature infant eyes (A, B), term infant eyes (C, D), and adult eyes (E, F), acquired with a handheld SD-OCT system (Bioptigen). (A, C, E) Scans are from African American subjects while (B, D, F) are from Caucasian subjects. CSJ was visible in the African American premature infant (A) and Caucasian premature infant ([B], white arrow). CSJ was not visible in the African American term infant (C) and adult (E), but is noted in the Caucasian term infant (D) and adult (F).

Figure 2

Subfoveal choroidal thickness in all four groups. The median subfoveal choroidal thickness is greatest in term infants (329 ± 66 μm). The median subfoveal choroidal thicknesses of all age groups are significantly different from one another except for the comparison between adult subjects and term-aged preterm infants where there is no statistical difference.

Figure 3

Preterm subfoveal choroidal thickness increased with age. Six subjects that had five or more visits (subjects 1–6) all showed the choroid thickness increasing with age. A Wilcoxon signed rank matched pair analysis including 13 subjects (P = 0.009) (subjects 1–14, excluding subject 3 since it did not have a visit in the young preterm age group) and a linear regression for all the preterm subjects in the study (P = 0.002), represented by the solid black line across the graph, also showed that choroid increased with age.

Figure 4

Choroidal thickness across vertical scans (superior to inferior) follow the same trend as central choroidal thickness with term infants having the greatest choroidal thickness followed by term-aged preterm infants then young preterm infants. Young preterm and term-aged preterm infants seem to have a slightly flatter overall choroid when compared to term infants.