With it's baselines up to 130 m, VLTI/GRAVITY is able to achieve more than a order of magnitude better angular resolution than single dish 10-m class telescopes. WIth this, we have been able to achieve 10-100 μas astrometric position on known exoplanets, allowing us to reveal small dynamical effects such as measuring the planet-planet perturbations in their orbits.

To the left is a plot of the orbit of HR 8799 e, with a 2x zoom in the bottom right panel to see the error bars from the single dish telescopes, and with 200x zoom in the top right panal to see the GRAVITY astrometric precision.

Source: https://www.aanda.org/articles/aa/pdf/2019/03/aa35253-19.pdf