Are you considered legally blind if it is just in one eye?

[Rainman12]

No. Based on Best eye worse than 20/200, or field of vision 20 degrees or less..

[DoninGA]

From the IRS Form 1040 Instructions page 16 - https://www.irs.gov/pub/irs-pdf/i1040gi.pdf#page=16

Blindness
If you weren’t totally blind as of December 31, 2021, you must get a statement certified by your eye doctor (ophthalmologist or optometrist) that:
• You can't see better than 20/200 in your better eye with glasses or contact lenses, or
• Your field of vision is 20 degrees or less.

If your eye condition isn't likely to improve beyond the conditions listed above, you can get a statement certified by your eye doctor (ophthalmologist or optometrist) to this effect instead.
You must keep the statement for your records.