When you have a patra, the inner eyes always have 24 hp, regardless of the setting `Eyes' HP`.
2.53: guys.cpp L10704
2.55: guys.cpp L14216
((enemy*)guys.spr(i))->hp=12*DAMAGE_MULTIPLIER;
This line is the cause; to use the existing `Eyes' HP` setting, it should be `->hp = dmisc3;` - though this may need a QR, or a new setting for the inner HP, for compatibility reasons.