From how it earned its name Eyebright has, of course, chiefly been used to assist with ailments of the eyes; conjunctivitis, red-eye, styes, itchy eyes, stinging eyes and weak vision from diverse causes.
Eyebright had the folklore reputation to be able to restore sight to people after their 'three score and 10' (70 years of age). Whilst this probably sounds like a complete exaggeration it should be considered that many such ageing people may have had degenerative changes to the structure of their eyes that could have been considerably improved with the regular use of Eyebright.