Unfortunately we can only use registered stock here. By registered I mean with the Hebridean Sheep Society, so we have each animals full pedigree ie a record of all the registered parents, grandparents and so on back to when Hebs were first registered with the Rare Breeds Survival Trust.
Split eyelids happen occasionally in multi-horned sheep of all breeds - Heb, Manx Loaghtan, Jacob, Navajo Churro etc. It is clearly associated with multi horns, but the exact genetics of the condition are not yet known. If it occurs in a female it is not too big a worry unless the eyes are badly affected, but because it appears to be hereditary to some (as yet unknown) degree, it is not usual to use a tup if he has a split and if you are breeding for breeding stock. The split is of the upper eyelid, so that there is a break in the smooth line - this can vary from very slight to a fully split eyelid and sometimes even marks on the cornea.
If all looks well then that is fine - don't worry about it
Hebs, especially the multihorns, are very striking and wonderful sheep so I hope you will breed up some more.