I suspect I have presbyopia or cataracts... Please recommend an ophthalmologist.

If you are in your late 40s, it is a good idea to get a checkup... especially since conditions like glaucoma have almost no symptoms, so you won't know if you don't get a checkup.

I had a check-up at Gangnam Cube Eye Clinic, and they even examined the fundus in detail. It puts my mind at ease that they checked everything at once.

I recommend comparing 2 or 3 places instead of just going to one.

My father also thought he just had presbyopia, so I was surprised to hear that he has early-stage cataracts...

Based on the symptoms you described, it sounds like presbyopia, but I think it would be a good idea to get a checkup.