Runescribe by Megan Derr

Near-blind without his glasses, regarded as a burden to his family, Tyri left his clan to attempt a career as a runescribe in the city, taking his mute sister Vess with him so she doesn’t grow up tormented as he was.
But finding a job proves more difficult than he anticipated, and his last hope to avoid being thrown out on the streets depends on the interview he has that morning.
A morning that comes crashing down on him by way of a thunderstorm and the stranger who runs into him and destroys his glasses…