Side effects are minor (sometimes I get a little irritable after work as it's wearing off) and the prescription is $10/month. But my glasses are on from when I

Side effects are minor (sometimes I get a little irritable after work as it's wearing off) and the prescription is $10/month. But my glasses are on from when I wake up until I go to bed, and I've never felt any eye strain from them. You shouldn't need a backup pair for that reason, there's probably something wrong with your prescription.