NORMAL VISION is perfect sight at all distances. The Snellen test card is the standard for testing the vision. When the ten foot line of the card can be read at ten feet or further, and fine print can be read at six inches or less, one has normal vision.
MYOPIA or NEAR-SIGHTEDNESS: The vision for near objects is good, while the distant vision is imperfect.
HYPERMETROPIA or FAR-SIGHTEDNESS: The sight is not so good at a near point as it is for more distant objects.
PRESBYOPIA or OLD AGE SIGHT: The vision is imperfect when the patient tries to read fine print at a near point. The distant vision may or may not be good.
ASTIGMATISM is an imperfect curvature of the eye. Usually the front part of the eye has one curve which is different from all the other curves.
CATARACT is an opacity of the lens in the pupil, which interferes with good vision.
RETINITIS PIGMENTOSA is a disease of the interior of the eye, accompanied by the formation of black pigment spots.
FLOATING SPECKS are not real, they are imagined.
IRITIS is an inflammation of the iris, or the colored part of the eye.
CHALAZION TUMOR is a swelling of one of the glands of the eyelids.
MEMORY, or IMAGINATION, is the ability to see or recall letters, or other objects, when the eyes are closed, as well as they can be seen with the eyes open.
The SNELLEN TEST CARD has letters or other objects printed in varying sizes. The smallest letter or picture seen clearly on the card is a measure of the vision.
POT HOOKS is the name used for test cards which have a letter "E" printed with the opening pointing up or down, in or out. The test letter is made of different sizes similar to other Snellen test cards. It is usually employed to test the vision of children or adults who do not know the alphabet. The smallest "E" which the patient recognizes "pointing" in the true direction, measures the amount of sight.
DIAMOND TYPE is one of the smallest types used in printing and helps to improve the vision if it is read every day.