A particularly interesting fresco of the Nativity is found in the little Greek church called the Omorfi/Omorphe Ekklesia (Ομορφη Εκκλησία) — literally “Beautiful Church” — on the island of Aegina (Αίγινα), off the coast of Piraeus.
It has the usual Byzantine elements common to the type, but with some interesting variations. The most obvious is that Mary — instead of lying on her pallet — is seated and nursing the child Jesus. We see the traditional ox and ass feeding from the manger beside her, but a very peculiar feature of this rendering is the cave in which she sits. The edges of the cave are ornamented with open eyes:
Iconologists customarily explain the cave eyes this way: First there is the common belief in the “Evil Eye,” and both newborn children and new mothers were thought to be particularly vulnerable to its influences. To counteract the Evil Eye, the superstitious used the principle of “like cures like,” so they used an eye — whether painted or in amulet form — to counteract the harmful influence of any potential Evil Eye.
The second — and related — potential source often mentioned for the eyes is the metaphor of man as a cave of robbers and demons, found, for example, in a Christmas homily by Anthimos of Athens:
“The Lord was born in a poor and humble cave, to transform man who is the cave and dwelling of the robber and the murderous demon, the fearful evil Devil, into the temple and house of the Holy Spirit.“
That man is the residence of demons is a notion found as early as the Epistle of Barnabas:
“Understand you. Before we believed in God, the
abode of our heart was corrupt and weak, a temple truly built by
hands; for it was full of idolatry and was a house of demons, because
we did whatever was contrary to God.”
In any case, the supposition is that the cave — being a potential residence of demons, whether in actuality or as a symbol of mankind — could have its potential evil averted by the use of painted eyes as talismans. So what we see in this depiction is the eyes painted on the cave to avert the Evil Eye from the mother and newborn child — at least that is a common interpretation. It is difficult to say if that was what the painter actually intended.
It is also possible that someone got a bit too literal in reading the Protoevangelion of James in Greek. Here is a relevant portion: