  We present a necessary condition for a pair of $\mathcal{C}(K)$ spaces to be
isomorphic in terms of topological properties of Cantor-Bendixon derivatives of
$K$. This in particular gives a completely new information about the perfect
kernels of such $K$. In the process, we extend known lower estimates of the
Banach-Mazur distance between a pair of spaces of continuous functions from the
case of scattered compact spaces to a more general setting. Next, we apply this
general result to deduce some new information about isomorphisms of spaces of
continuous functions over Eberlein compacta of height $\omega+1$. Further, we
show that isomorphisms of $\mathcal{C}(K)$ spaces preserve the spread of $K$,
and we also prove some new results for pairs of spaces of continuous functions
whose Banach-Mazur distance is less than $3$.
