Three-dimensional assessment of vascular and perivascular characteristics in subjects with retinopathy of prematurity

Abstract

Purpose: To study vascular features detected with spectral domain optical coherence tomography (SD-OCT) in subjects undergoing retinopathy of prematurity (ROP) screening.

Design: Cross-sectional study.

Participants and controls: Fifty-seven premature neonates, 10 with plus disease in at least 1 eye and 47 without plus disease.

Methods: Bedside noncontact SD-OCT imaging was performed after obtaining parental consent on 97 consecutive infants between January 2009 and September 2012. Fifty-seven subjects (31-49 weeks' post-menstrual age) who had an SD-OCT scan in at least 1 eye showing the edge of the optic nerve and at least 1 major retinal vascular arcade were included. One eye per subject was randomly selected for analysis. Two masked graders evaluated scans for (1) retinal vessel elevation, (2) scalloped retinal layers, (3) hyporeflective vessels, and (4) retinal spaces. To coalesce the weight of these features, a Vascular Abnormality Score by OCT (VASO) was created. For quantitative assessment of vessel elevation, retinal surface maps were created.

Main outcome measures: Prevalence of SD-OCT vascular abnormalities, the VASO, intergrader agreement, and presence of elevation on surface maps.

Results: From among 67 SD-OCT characteristics that were recorded, the most common characteristics found were vessel elevation (44%), hyporeflective vessels (40%), scalloped layers (22%), and retinal spaces (11%). Features significantly associated with plus disease were vessel elevation (P = 0.01), hyporeflective vessels (P = 0.04), and scalloped retinal layers (P = 0.006). Intragrader agreement was between 74% and 90% for all features. The VASO was significantly higher in subjects with plus disease (P = 0.0013). On 3-dimensional SD-OCT volumes, eyes with plus disease had greater retinal surface elevation that more often matched en face retinal vascular patterns.

Conclusions: We present a novel 3-dimensional analysis of vascular and perivascular abnormalities identified in SD-OCT images of eyes with ROP. The SD-OCT characteristics that are more common in eyes with plus disease provide the first in vivo demonstration of the effects of vascular dilation and tortuosity on perivascular tissue. The VASO and surface maps also delineate the severity of vascular pathology in plus disease. Further studies evaluating these findings in eyes with pre-plus versus normal posterior pole vessels may determine the usefulness of SD-OCT in the early detection of vascular abnormalities in ROP.

Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1

Three-dimensional reconstruction of Spectral Domain Optical Coherence Tomography (SDOCT) scans of a 42 week post-menstrual age (PMA) neonate (A). Vessels were labeled on each SDOCT cross-sectional frame (B-scan) and then the three-dimensional reconstruction with volume rendering was achieved using AVIZO software. Green areas correspond to retinal spaces. These areas were located at acute vessel angulations. SDOCT scans on B and C show the corresponding retinal spaces (green arrows) which are hyporeflective spaces located between vessels. These spaces do not create a shadowing effect as opposed to the normal shadowing effect produced by blood vessels.

Figure 2

Spectral Domain Optical Coherence Tomography (SDOCT) scans from a 31 weeks post-menstrual age (PMA) neonate (A) with Retinopathy of Prematurity (ROP) zone II, stage 2, and normal vasculature per clinical exam and a 48 weeks PMA neonate, ROP zone II, stage 3 and Plus disease (B). Left panel shows no vessel elevation on (A) and severe vessel elevation on (B). Middle panel images (C,D) are retinal images created from axial compression of SDOCT scans. Panels E and F contain same scans as A and B respectively but highlights the smooth retinal layer contour (E) and the scalloped pattern on (F). Red asterisks are placed over vessels and the corresponding location on the retinal image is shown on (C and D). White arrows point to shadow produced by the corresponding vessels. On E and F, the light green line (upper) represents inner plexiform layer and dark green line (lower) represents the outer plexiform layer.

Figure 3

Spectral Domain Optical Coherence Tomography (SDOCT) scans from a 35 weeks post-menstrual age (PMA) neonate (A) and a 43 weeks PMA neonate (B) showing retinal vessels as hyperreflective round-oval structures located at the level of ganglion cell layer. SDOCT on (C) is from a 39 weeks-old PMA neonate with a mid-reflective vessel. SDOCT scan on (D) is from a 48 weeks-old PMA neonate where multiple hyporeflective vessels can be observed (under red asterisks. These vessels are also identified on SDOCT scans due to the hyporeflective “shadowing” columns they produce.

Figure 7

Comparison of color thickness maps in controls and subjects with plus disease. The black area corresponds to the optic nerve. In the plus disease group, all the color thickness maps, except (C) presented retinal elevation that followed the vascular pattern (shown in the corresponding retinal images). The color map on (C) presented elevation only near the optic nerve. Most of the control group maps (A-E) showed no elevation and few of them (F,G,H) had only small islands of elevation near the optic nerve.