The main part of the post is how to get brighter eyes and since its in the strobe and lighting section and not post process section. My main statement sticks, the more light you get into the eyes the brighter they will be. The modeling light is key if you want more iris and less pupil. The brighter the modeling light / ambient light in the studio the small the pupil and larger the iris. The more reflection off the iris the brighter they will be come and no need to pp unless your adding sharping.
I certainly agree that having a dilated pupil is distracting and unnatural looking. And it is a very common mistake we see a lot of out there. And again....at the other extreme, if you have someone in very bright light where their eye is totally stopped down to like f/132 
, then that too looks weird to me.
The reason I asked the OP to show us an example where they thought could be better, was because I was wondering if perhaps it is a framing/composition issue. Sometimes photographers look at a photo like that, and for instance, it's a full body shot, plus some more BG, etc, and then they wonder why the eyes are not a prominent part of the photograph. A shot like that, the eyes might only be a fraction of one percent of the entire image.....so we won't be "seeing much light in the eyes" so to speak.
Another thing I find distracting is when the eyeball is turned to an odd position in the socket, leaving a lot of white on one side, and none on the other. I spend a fair bit of time directing the subject to move their eyeball here and there, after I get their head positioned where I want it.
My main statement sticks, the more light you get into the eyes the brighter they will be. The modeling light is key if you want more iris and less pupil. The brighter the modeling light / ambient light in the studio the small the pupil and larger the iris. The more reflection off the iris the brighter they will be come and no need to pp unless your adding sharping.
