As a NES, but not a teacher, I would have said:
1. I am astigmatic.
2. I am both astigmatic and short-sighted.
3, I am both astigmatic and long-sighted.
4. I am presbyopic.
5, I am both astigmatic and presbyopic.
"My eyesight is mixed .." doesn't work for me
Presbyopia is a noun for long-sightedness (inability to focus on near objects) rather than an adjective.
Hope this helps