The timeframe isn't quite right (it was published in 2010), and a few other details are off as well, but the general gist of this sounds like The Passage by Justin Cronin. The novel starts early as the vampires start to take over, and then jumps to a situation very much like you remember. It's a small group of survivors.
Children are raised communally and told the truth at the age of eight (not eighteen), as described in this interview:
This is a kind of deep greed that they commit, because they fail to notice that we are already immortal, because the future we do not personally live to see is the one our children live in. The sanctuary is a protective enclave within this colony of survivors. It sits at the center. Its an old elementary school. It's fortified. It is the last retreat in the event that the Colony is invaded. And all the children in the Colony live there until the age of eight, and they live in a bubble of not knowing.
The world in which they live is one that is so potentially psychologically traumatic that the founders of this society have decided, well, we'll give people eight years not to know the truth. And so the children live there sort of sealed away, not just from other people, but from the knowledge of what the world really is. And one person, who's called Teacher, it's her job when you turn eight to tell you what the truth is, so that you dont hate your parents for it, actually. So she bears the collective trauma of this resentment.
A character with progressive vision loss is Galen Strauss described (in the Wiki's "Characters" page) as:
A member of the First Colony watch, Galen experiences progressive loss of vision—he suffers from severe glaucoma, which renders him almost entirely blind.