You’ve hit on a problem that the Deaf community faces. There’s often an entire Deaf society in places. Deaf jobs, Deaf schools (including universities), Deaf media… They do read English but it’s harder and it’s not their primary language (though I’ve heard the internet is helping a lot there).
But yeah, there are Deaf universities, including prestigious ones like Gallaudet. Nobody teaches medicine or engineering in sign language from what I can see. I did check and I was pleasantly surprised that Gallaudet offered shit like math, biology, and IT with even grad programs in stuff that isn’t explicitly about deafness.