Ocular blood flow in low-birthweight neonates

Abstract

Purpose : Low-birthweight premature neonates are at risk for development of retinopathy of prematurity (ROP), a leading cause blindness in infancy. Timely detection of neovascularization in the setting of "plus disease," thought by some to represent a state of abnormally high retinal blood flow, is key to preventing vision loss. We here describe use of plane-wave ultrasound to image and measure blood flow in the central retinal artery (CRA) and vein (CRV) and the short posterior ciliary arteries (SPCA) in a cohort of low birthweight neonates at risk for ROP.

Methods : We performed plane-wave imaging with a Verasonics Vantage 128 ultrasound system using an 18 MHz linear array probe. Imaging was performed in a horizontal plane including the optic nerve head. Six plane wave transmissions over a ±9^o angle were added coherently to form 3000 compound images/sec. We acquired data continuously for 1.5 seconds in each scan. Plane-wave data were post-processed to form color-flow images and flow velocities were determined from spectrograms of the CRA, CRV and one or more SPCAs.
Both eyes of 10 neonates (3 M, 7 F) were examined in the neonatal intensive care unit, and all but one subject had a followup exam. Mean postmenstrual age (PMA) at birth was 26.3 weeks and mean birthweight was 731g. The average age at time of exam was 83 days (PMA=37.4 weeks). ROP status was graded by the ophthalmologists, masked with respect to ultrasound analyses, using indirect ophthalmoscopy.

Results : Color-flow power-Doppler images are filtered to suppress stationary or slow-moving structures. Arterial flow is depicted in red and venous flow in blue. In the Figure, the CRA and CRV are readily seen in close proximity. SPCAs feeding the choroid are also easily seen.
The table summarizes mean±SD systolic (Vs) and end-diastolic (Vd) velocities (mm/sec) in the major vessels by ROP stage.

Conclusions : Although the cohort size is small in this pilot study, we found that flow velocities in the major orbital vessels increased with the severity of ROP stage (p <.01). This finding suggests that high-resolution plane-wave ultrasound may represent a valuable dynamic imaging tool to assess ROP severity and progression, as well as gain important insights into ROP pathogenesis and response to treatment.

This is a 2020 ARVO Annual Meeting abstract.

 

Directionally encoded power Doppler image of the posterior pole in a Stage 0 eye.

 

Mean values and standard deviations of systolic and end-diastolic velocity for the major retrobulbar vessels by ROP stage.