  We present a comment to a recent paper by Dominguez et. al. They claimed that
the electrostatic interaction between charged colloids trapped at an interface
formed by a dielectric and a screening phase is always isotropic to order
$d^-3$. Base on this result, they claimed that in-plane dipolar attraction of
order $d^-3$ between colloids cannot exist, in contrast to previous proposals.
We point out that their analysis is not completed and anisotropic (dipolar)
interaction between colloids can exist up to order $d^-3$.
