Before revision:  Le and Solomon (2020) constructed Steiner (1+\varepsilon)-spanners of lightness O(\varepsilon^{-1}\log\Delta) in the plane, where \Delta \in \Omega(\log n ) is the spread of the point set, defined as the ratio between the maximum and minimum distance between a pair of points.
After revision:  Le and Solomon (2020) constructed Steiner (1+\varepsilon)-spanners of lightness O(\varepsilon^{-1}\log\Delta) in the plane, where \Delta \geq \Omega(\sqrt{n ) is the spread of the point set, defined as the ratio between the maximum and minimum distance between a pair of points.