It is dependent on the ability of the eye to refract light rays and focus them on the retina.
The shape of the eye is one determinant in the refractive and focusing processes of vision.
What is emmetropia?
It is the normal refrective condition of the eye in which light rays are brought into sharp focus on the retina.
What is Myopia?
Nearsighted...It is generally inherited.
Occurs when the eye is longer than normal
Light focuses in front of the retina.
What is hyperopia?
It is farsightedness. an inherited condition
-eye is shorter than normal
-light rays focuses behind the retina
What is astigmatism?
familial condition in which the refraction of the light is spread over a wide area rather than on a distinct point on the retina. in the normal eye, the cornea is round shape, whereas, in astigmatism cornea curves more in one direction than another.
What is presbyopia ?
it is an age related condition in which the lens of the eye loses the ability to accommodate. As a result, light is focused behind the retina and focus on near objects becomes difficult.
where are blind spots located in the eye?
in the localized damaged areas.
Optive nerve or globe lesion results in?
unilateral blindness meaning you are blind with one eye
What is optic chaism lesion?
(When your blind from both end sides of your eye) bilateral heteronymous hemianopsia (loss of temporal visual fields)
What is retinal detachment?
vision diminishes in affected area.
What is left hemianopsia?
Lesion occurs in uncrossed fibers of optic chiasm
what is homonymous hemianopsia?
Right optic or optic radiation lesion resulting in loss of right nasal and left temporal fields.
What is eye movement controlled by
by six extraocular muscles and cranial nerve III, IV, VI.
How is muscle weakness or dysfunction of a cranial nerve can be identified
by assesing the fields of gaze, corneal light reflex, and performing the cover test.
what is strabismus?
a condition in which the axes of the eyes can't be directed at the same object.
There are two types of strabismus which are
esotropia and exotropia
convergent in which the eye deviates inward
divergent in which the eye deviates outward
Adie's Pupil also known as
what is Adie's pupil?
Unilateral and sluggish pupillary response
what is Argyll Robertson Pupils?
Pupil exist bilaterally and are small, irregular and nonreactive to light.
when does Argyll robertson pupils occur
it occurs with central nervous system disorders including tumor, syphilis and narcotic use.
What is Anisocoria?
unequal pupillary size, which may be normal finding or central nerous system disease
what happens when cranial nerve III is damaged?
it results in unilaterally dlated pupil.
No reaction to light.
Ptosis may be seen
it is a result of blockage of sympathetic nerve stimulation.
what are the findings of horner's syndrome?
unilateral, small regular pupil that is nonreactive to light. Ptosis and anhidorosis of the same side accompany the pupillary signs.
What is Mydriasis?
a fixed and dilated pupils. it occurs with sympathetic nerve stimulation, glaucoma, central nervous damage or deep anesthesia.
what is miosis?
a fixed and constricted pupils. it occurs with the use of narcotics, damage to the pons or a result of treatment for glaucoma.
what is monocular blindness?
it results in direct and consenual response to light directed in the normal eye and absence of response in either eye when light is directed in the blind eye.