Eyes Flashcards
What is the functions of the orbit of the eye?
Ensures that the eye’s functions are optimized
*Its a quadrilateral-shaped bony socket
What is the sclera of the eye?
White covering of the eyeball
*continuous with the dura of the central nervous system
What is the iris of the eye?
Colored circular muscle, that gives us our eye color
What happens when the muscles of the iris dilates?
It controls the amount of light allowed to enter the eye through the central aperture
*Which is the pupil
What is the cornea?
The cornea covers both the pupil and iris and is continuous with the sclera.
What is the palpebral fissure?
The opening between the eyelids
What is the conjunctiva of the eye?
A thin transparent mucous membrane that covers the inner surfaces of the eyelids & eye
*highly vascularized
*Has two components
What is the bulbar conjunctiva?
Covers most of the anterior eyeball
*Meets the cornea at the limbus
What is the limbus?
The point where the cornea and sclera meet
What is the palpebral conjunctiva?
Lines the eyelids
What is the function of the conjunctiva?
To lubricate, protect the eye
What is the function of the meibomian glands?
They open on the lid margin and provide oily lubrication to the ocular surface
What is the primary muscle that moves the upper lid?
Levator palpebrae superioris
*Innervated by cranial nerve III (oculomotor nerve)
What is the function of the tear film?
-Protects the conjunctiva and cornea from drying
-Inhibits microbial growth
-give a smooth surface to the cornea
What are the components of the tear film?
Oily layer: from the meibomian glands
Aqueous layer: from the lacrimal glands
mucinous layer: from the conjunctival glands
Where is the lacrimal gland located?
Lies in the superolateral orbit
Where does tear fluid flow to? (Part one)
Spreads across the eye and drains medial through two tiny holes called the lacrimal puncta
*The tiny holes are located on the superior and inferior medial eyelid margin
After tears exit the lacrimal puncta where do they go?
Then pass to the canaliculi into the lacrimal sac and into the nose through the nasolacrimal duct
Where is the lens located in the eye?
Behind the iris
What controls the thickness of the lens?
Contraction or relaxation of the ligaments in the ciliary body
*which then allows for the eye to focus on near or distant objects
What is accommodation?
Allows the eye to adjust or focus on near or distant objects
What is the function of the retina?
Its the sensory part of the eye
What are the three chambers that contain fluid in the eye?
Anterior chamber
*Between the cornea and iris
Posterior chamber
*Between the iris and the lens
Vitreous chamber
*Between the lens and the retina
What is between the anterior and posterior chamber?
Filed with a clear liquid called aqueous humor
*Produced by the ciliary body
*will drain through the canal of Schlemm
What is the vitreous chamber filled with?
Vitreous humor
*helps maintain the shape of the eye
What is the optic disc and when is it seen?
-The optic disc is usually seen through the ophthalmoscope
-Where the optic nerve is
What surrounds the fovea?
the macula
What is the definition of a visual field?
The entire area seen by an eye when it looks at a central point
What are visual fields limited by?
Brows above
Cheeks below
Nose medially
What produces a blind spot?
A lack of retinal receptors at the optic disc
*Approximately 15 degrees temporal
Describes what happens when a person uses both eyes to see?
The two visual fields overlap which allows for stereopsis or 3D depth perception (bi-ocular vision)
What is direct reaction to light?
When there is pupillary constriction to the eye that is getting light shined on it
What is consensual reaction to light?
Pupillary constriction to the contralateral eye
What is the cranial nerve responsible to light reaction?
Cranial nerve II optic nerve
What are the two reasons for changes in pupillary reactions
- Light
- Effort focusing on near objects
What is the cranial nerve that facilitates near reaction or accommodation
CN III ocular motor
Is accommodation visible to the examiner?
NO
*accommodation takes places behind the iris
What are the extra ocular eye muscles?
Lateral and medial rectus
Superior and inferior rectus
Superior and inferior obliques
What is the action of the superior recuts muscle?
Moves the eye upward
What is the action of the inferior recuts muscle?
Moves the eye downward
What is the action of the medial recuts?
Moves the eye inward toward the nose
What is the action of the Lateral recuts?
movs the eye outward away from the nose
What is the action of the superior oblique muscle?
Rotates the top of the eye toward the nose around the long axis and downward
What is the action of the inferior oblique muscle?
Rotates the top of the eye away from the nose around the long axis and upward
What cranial nerves are innervate the extraocular muscles?
Abducens CN VI
Trochlear CN IV
Oculomotor CN III
What muscles does the Abducens nerve CN VI innervate
Lateral recuts
What muscles does the Trochlear nerve CN IV innervate
Superior oblique muscle
What muscles one’s the oculomotor nerve CN III innervate?
Medial rectus
Superior rectus
Inferior rectus
Inferior oblique
What is the purpose of testing the EOM?
-Can test the function of each CN innervation of the six EOM muscles
-Can also test for eye convergence
What is eye convergence?
Focus on a close object to the point where its no longer possible (medial rectus III)
What is diplopia?
Double vision
*Possible early/initial sign of a neurological disorder *Lesion in the brain stem
What is hyperopia?
Farsightedness
What is presbyopia?
Aging vision
What is myopia?
Nearsightedness
What are the parts of an eye exam?
- visual acuity
- Inspection/ Palpation
- Visual fields by confrontation
- Pupils
- EOM and convergence
- Fundoycopic examination
What are PERRLA stand for?
Pupils are equally round and reactive to light and accommodation
What are the two types of vision tests
Snellen
Rosenbaum (can be down bedside)
What does visual acuity asses?
Central vision
*CN II optic
What does OD stand for?
Right eye
What does os stand for?
Left eye
What does OU stand for?
Both eyes
What is ptosis?
Drooping of the upper eyelid
*Damage to the ocular motor
What is exophthalmos?
Lid retraction
Caused by hypothroidism
eyeballs will be protruding forward
What is entropion?
Inward turning
What is ectropion?
Lower eyelid turns outward
*Tears wont drain and exposed conjunctiva
What is a chalazion?
Non-tender inflammation caused by a blockage of the meibomian gland
What is a xanthelasma?
Raised yellow plaques
*Lipid disorder
What is a subconjunctival hemorrhage?
Benign hematoma of the conjunctiva
How do you inspect the cornea and iris?
Use temporal lighting
*note any unusual shadow patterns
*will show abnormalities in the intro-ocular pressure
What is a corneal arcus?
A thin gray white arch common in elderly
What is pterygium?
A thickening of the bulbara conjuncva
*It impedes the pupil
When do you perform lid eversion?
If there is a foreign body suspected
What does it mean if there is a temporal defect in the eye?
There is a nasal defect in the other eye
What is a horizontal visual field defect?
Occlusion of a branch of the central retinal artery
What is a bitemporal hemianopsia?
A lesion at the optic chiasm
*visual loss involves the temporal half of each field
What is left homonymous hemianopsia?
A lesion of the optic tract, interrupts fibers on the same side of both eyes
*visual loss involves half of each field (left side)
What is a homonymous left superior quadrant defect
A partial lesion of the optic radiation in the temporal lobe
*1/4 of eye is blocked upper quadrant
What is miosis?
Constriction of the pupil
What is mydriasis?
Dilatation of the pupil
How does the eye accommodate for close vision?
It tightens the ciliary muscles, allowing the pliable crystalline lens to become more rounded
What are argyll robertson pupils?
Small irregular pupils
*will not react to light
*will accommodate
What is exotropia?
Deviating eye turns outward
What is esotropia/
Deviating eye turns inward
What is papilledema?
Optic disc swelling secondary to increased intracranial pressure
*HTN
*Idiopathic
*Cerebral edema
What is a kayser-fleischer ring?
A golden to red brown ring, sometimes shading to green or blue. Caused by copper deposition in the periphery of the cornea found in Wilson disease
What is blepharitis?
A chronic inflammation of the eyelids at the base of the hair follicles
*commonly caused by S. Aureus
What is a pinguecula?
A harmless yellowish triangular nodule in the bulbar conjunctiva on either side of the iris.
*can appear with aging
What is a episcleritis?
A benign, usually painless localized ocular inflammation of the episcleral vessels
