P4-33: Variations of retinal arteriolar wall-lumen ratio depend on mechanism of blood pressure changes

Abstract

Background A recently developed non-invasive opto-electronic technology (Adaptive Optics Camera, AOC) provides a morphologic analysis of the retinal arteriolar tree. Coupled with a validated semi-automated segmentation software it allows reproducible and reliable measurements of wall thickness (WT), internal diameter (ID), wall cross sectional area (WCSA) and calculation of wall-to-lumen ratio (WLR). Our aim was to assess the determinants of WLR along the temporal retinal artery and in case of acute Blood Pressure (BP) rise or drug-induced short term BP drop. Methods We studied 3 groups of patients : 1/ We consecutively enrolled 48 patients and calculated WLR before the first bifurcation (parental vessel) and on its large and small post-bifurcation branches on the right eye temporal superior artery. 2/ In a subgroup of 10 patients WLR was measured at rest and right after exercise dynamic test. 3/ In 55 hypertensive subjects AOC assessment was repeated after a median of 49 days in 27 subjects with stable BP and 38 days in 28 subjects with a drop in BP secondary to antihypertensive drug adaptation. WT and ID were directly measured using non-invasive rtx1® AOC (ImagineEyes-Orsay, France) and a dedicated software analysis system was used to calculate WLR and WCSA. BP was measured at the time of AOC examination in standard conditions. Hypertension was defined as the presence of Systolic Blood Pressure (SBP)>140 mmHg and/or Diastolic blood pressure (DBP)>90 mmHg. Results 1/ In the first group, in both normo- and hypertensive patients, a significant decrease in ID, WT and WCSA was observed on post-bifurcation branches whereas WLR remained constant (table 1, next page). 2/ In the second group, while SBP acutely increased of 47±8 mmHg, ANOVA analysis did not show any significant changes in WLR. 3/ At 6 weeks, in the follow-up group with a short-term SBP drop (–19.3±7.7%), a decrease of WLR (–7.0±8.0 mmHg) due to ID increase (+5.6±5.9%) without significant changes in WT and WSCA were observed. No changes were observed in the group with a stable BP (see table next page). Conclusions WLR, the index of remodeling in retinal small arteries, is constant along the arterial tree despite changes in WT and ID. While WLR did not change during acute exercise-induced BP surge, it decreased due to a ID increase after a short-term drug-induced BP drop. Those results confirm the homogeneity of remodeling along the retinal arteriolar tree and that mechanisms of BP changes have different effects on remodeling. P4-33 – Tableau : Retinal arteriolar microvascular indices in parental vesse, large and small branches Parental Vessel Large Branch Small Branch p Wall to lumen ratio 0.295±0.051 0.296 ± 0.064 0.317±0.071 NS Internal diameter - μm 79.8012±9.23 71.0716±10.78¥ 54.498±8.05*† <0.001 Wall Thickness - μm 23.4015±4.12 20.7199±4.13§ 17.1838±4.31*† <0.001 Wall Cross Sectionnal Area - μm 3376.34±849.73 2680.75±775.56¥ 1891.40±1110.74*† <0.001 Small branch vs parental vessel: * p<0.001. Small branch vs large branch: † p<0.001. Large branch vs parental vessel: § p<0.05; ¥ p<0.01 Full-size table Table options View in workspace Download as CSV