Contrast sensitivity significantly contributes to overall visual quality and partially explains why a person seeing “20/20” may still be afflicted by poor vision. From a patient's point of view, poor contrast sensitivity means constantly having foggy, hazy, or cloudy vision. When severe, it greatly affects night driving, visualizing road signs, and seeing pedestrians in the dark.

Color blindness is the term most used to describe a person having a color deficiency – very few individuals are truly color blind in the sense that they only perceive different shades of gray. Determination of proper color vision is necessary as certain careers require normal color vision. Clinicians may also assess color vision to gauge retinal and optic nerve health.

Central visual acuity, usually referred to as visual acuity, is a measurement of visual sharpness when looking directly at a target. Though a best corrected (i.e. with glasses) visual acuity of worse than 20/20 often indicates an ocular abnormality, such as cataracts or macular degeneration, achieving 20/20 vision does not exclude the possibility of an underlying ocular problem

Management of vascular risk factors in cases of glaucoma is the standard nowadays. Nocturnal hypotension or significant fluctuations of blood pressure can provoke ischaemic episodes at the optic nerve head which may lead to progression of glaucomatous optic neuropathy. 24-hour 
ambulatory blood pressure monitoring can play important role for patients with normal tension glaucoma.