Usage of "Instill Yourself"

English as a Second Language English Vocabulary, Grammar and Idioms
1

Hi again,
Here are a couple of situational questions. I’ll be really thankful if you give me the proper terms:

  1. What is the expression to ask about the amount of weakness(far-saightedness or near-sightedness) in one’s eyes?
  1. What is it called when something is wrong but you try to believe it’s right. Can we say you instill yourself that it’s right?
2

You could ask “How is your vision?” Or you can ask about “visual acuity”. Or you might begin by asking someone whether they have “20/20 vision”.

Words/phrases that come to my mind are “insist (on believing)” and “fool oneself”, for example. Based on your description, “instill” seems quite inappropriate to me.
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