Since you mention zenni… If you are using a 27" monitor and blended bifocals, you really owe it to yourself to get a pair of $14 single vision computer glasses

Since you mention zenni… If you are using a 27" monitor and blended bifocals, you really owe it to yourself to get a pair of $14 single vision computer glasses tuned to your work distance. (anti glare pushes the price up from $7.)