It’s written éar and éas and must be pronounced [e:r] [e:s].
A Marcoman, a chara, where did you find these spellings? I suppose it’s hard to tell what is the correct spelling, given the fact that hardly anyone uses Irish names for the letters, but The Christian Brothers’ Grammar spells both letters with a short “e”.
Sorry, I misread those names. Then they sre pronounsed [ar] and [as], e is not pronounced before a at the beginning of words if they are not preceded by the article (it is not pronounced anyway but it slenderizes the previous consonant).