Abstract
Purpose :
Plane-wave (PW) ultrasound with a linear array probe is capable of visualizing and measuring retrobulbar blood-flow. The goal of this study was to determine if PW ultrasound could be used to image and measure retorbulbar blood-flow velocities in preterm neonates and assess the association of these velocities with retinopathy of prematurity (ROP) stages and zone.
Methods :
Ultrafast PW imaging of the perioptic region was performed with a Verasonics Vantage 128 ultrasound system using an 18 MHz linear array probe. Both eyes of 26 low-birthweight subjects at risk for ROP were scanned in the neonatal intensive care unit. Each scan was compounded from six scan angles, at a rate of 3000 compound scans/sec for 1.5 seconds, capturing at least two cardiac cycles. 16 subjects were scanned twice bringing the total number of eyes scanned to 84. All subjects had a birth-weight of less than 1500 g and a gestational age of less than 30 weeks. PW data were post processed to form color-doppler images and flow-velocity was measured in the central retinal artery (CRA), central retinal vein (CRV) and short posterior ciliary artery (SPCA) using spectrogram analysis. Findings were compared to ophthalmoscopic grading, with ultrasound and ophthalmoscopic findings masked until completion.
Results :
Minimal change in arterial or venous flow was observed in stage 1 and 2 ROP, but systolic and diastolic flow velocities increased significantly (p<.001) compared to non-ROP at stage 3 in the CRA (from 39±14 mm/sec to 64±20 mm/sec systolic) and CRV (from 19±6 mm/sec to 31±12 mm/sec systolic) Systolic flow velocity increased as well in the SPCA (from 45±14 mm/sec to 58±15 mm/sec, p=.007). Resistance indices did not change significantly. Five stage-3 subjects with pre-plus disease did not have significantly different flow velocity than other stage-3 subjects. There was no correlation between flow velocity and blood pressure.
Conclusions :
Flow velocities in the major orbital vessels increased at ROP stage 3. If plus disease is caused by high retinal flow velocities, its detection by PW ultrasound may represent a valuable tool to assess ROP risk in low birthweight neonates, especially because the exam can be performed more frequently than dilated ophthalmoscopy. With few pre-plus and no plus disease in this series, this hypothesis remains to be explored in a larger cohort.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.