Visual acuity
Ability to perceive and comprehend the sense of sight
Snellen charts
Used to test distant vision (nearsightedness) ; can contain pictures or letters which have specific heights
20/20 vision
Standing 20 feet from a chart, and can see characters that are 20 millimeters high
Myopia
Nearsightedness
Jaeger system
Tests defects in close vision (farsightedness); uses printed card with short paragraphs
Hyperopia
Farsightedness
Ishihara method
Tests defects in color vision/ blindness; contains series of numbers printed in colored dots against a background of dots in contrasting color
OD
Abbreviation for right eye
OS
Abbreviation for left eye
OU
Abbreviation for both eyes
Ophthalmoscope
Instrument for checking the eye
Tonometer
Instrument to measure intraocular tension or pressure; increased pressure often indicates glaucoma