Concentration & Evil Eye

[Pex]

The Witch's Evil Eye hex allows the option of giving a penalty to the victim's ability check or skill check. Does the concentration check, to cast defensively for example, count as either of those? I lean towards it being an ability check, but I couldn't find clarification, if any, in the rules. The rules are naming it a "concentration" check specifically, implying a different type of check altogether that Evil Eye can't affect because it's not given as an option.

[Psyren]

It's not clear unfortunately - though I will point out that I've seen them listed separately, suggesting they are not the same (e.g. the Medium (http://www.d20pfsrd.com/occult-adventures/occult-classes/medium)'s Marshal spirit has an ability that buffs your ability checks, skill checks, concentration checks, attack rolls or saving throws once per round.)

[Kurald Galain]

The Witch's Evil Eye hex allows the option of giving a penalty to the victim's ability check or skill check. Does the concentration check, to cast defensively for example, count as either of those?

Yes, a concentration check is an ability check, as per the definition of "ability check". Yes, a concentration check explicitly benefits from (e.g.) a Circlet of Persuasion, assuming you're a charisma-based caster of course, as per the FAQ and explicit response from the game designers. Yes, that means it is penalized by Evil Eye as well.

[Pex]

Cool. Thanks.