Retinal Vascular Response to the Handgrip Test in Type 1 Diabetes using OCT-Angiography

Abstract

Purpose : Autonomic changes and inflammatory mediators’ production occur early in diabetes mellitus (DM). Isometric exercise, such as the Handgrip test, induce a sympathomimetic response with an increase in arterial pressure and peripheral vasoconstriction. We aimed to compare the retinal vascular response and inflammatory mediators between patients with type 1 diabetes (T1D) without diabetic retinopathy, and an age and gender-matched cohort of healthy subjects, using ocular coherence tomography angiography (OCT-A).

Methods : Comparative cohort study. The handgrip test was performed using the Jamar® hydraulic dynamometer. Maximal grip force (MGF) was calculated first, and the participants were asked to keep a continuous contraction equal to a third of MGF during three minutes. OCT-A (AngioVue®) was carried out at baseline and 90 seconds after the beginning of the handgrip test. Macular superficial and deep vessel densities were calculated using the built-in software Angioanalytics®. A quality score equal or higher than 8/10 was required in all exams. Tumor necrosis factor (TNF) and interleukin-1-beta (IL1b) concentrations were determined in tears and venous blood samples of all participants. Mean comparison analyses were performed using STATA v14.

Results : Studied population included 48 subjects (24 T1D), with a mean age of 34.4±9.7 [range 18-59] years. Three minutes after the handgrip test start, heart rate and systolic and diastolic blood pressure increased in both groups compared to baseline conditions, as a consequence of sympathetic nervous system activation. In the control group, the handgrip test induced a decrease in vessel density in both superficial and deep plexus of parafoveal and perifoveal regions (all p<0.05). However, in the T1D group, this physiologic response was not observed and vessel density did not change significantly during isometric exercise. Tear TNF concentration was higher in patients with T1D (0.26±0.06 pg/mL vs. 0.05±0.03 pg/mL, p=0.01), but this was not associated with the retinal vascular response pattern. Tear IL1b and serum TNF/IL1b concentrations were not significantly different between groups.

Conclusions : Our work suggests there is an early impairment of the physiologic retinal vascular response in patients with T1D without clinical diabetic retinopathy.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.