word | definition |
accommodation | the process whereby the eyes make adjustments for seeing objects at various distances. These adjustments include constriction(narrowing) or dilation(widening) of the pupil, movement of the eyes, and changes in the shape of the lens. |
convergence | the simultaneous inward movement of both eyes (toward each other), usually in an effort to maintain single binocular vision as an abject comes nearer |
ectropion | the eversion of the edge of the eyelid |
entropion | the inversion of the edge of the eyelid |
anisocoria | a condition in which the pupils are unequal in size. This may be congenital (present at birth) or caused by a head injury, aneurysm, or pathology of the central nervous system |
cataract | the loss of transparency of the lens. This may be congenital (present at birth) or caused by trauma (injury) or disease; however, the formation of most cataracts is associated with ageing |
nystagmus | an involuntary, constant, rhythmic, movement of the eyeball |
glaucoma | characterized by increased intraocular pressure. If untreated this pressure damages the optic nerve and causes the loss of peripheral vision and eventually blindness |
diplopia | also known as double vision; the perception of two images of a single object |
nyctalopia | also known as night blindness; is a condition in which the individual has difficulty seeing at night |
presbyopia | describes the changes in the eyes that occur with aging |
strabismus | also known as squint; is a disorder in which the eyes cannot be directed in a parallel manner toward the same object |
esotrophia | also known as cross-eyes; is strabismus characterized by an inward deviation of one eye in relation to the other |
exotropia | also known as wall-eye; is strabismus characterized by an inward deviation of one eye in relation to the other |
astigmatism | a condition which the eye does not focus properly because of unequal curvatures of the cornea |
hyperopia | also known as farsightedness; is a defect in which light rays focus beyond the retina. |
myopia | also known as nearsightedness; is a defect in which light rays focus in front of the retina. |