Eye Flashcards
Describe the path of tears
Lacrimal gland under edge of eyebrow - drains into eye
Lacrimal canals drain tears from eye into lacrimal sac
This drains into the nasolacrimal duct which drains into inferior meatus of the nasal cavity
Which bones make up the orbit?
Sphenoid Frontal Ethmoid Lacrimal Maxillary Zygomatic
Which fissure is palpable on the outer edge of the orbit?
Frontal-zygomatic
What are the boundaries of the orbit?
Apex = optic canal Superior = frontal and sphenoid Lateral = zygomatic and sphenoid Medial = ethmoid, maxillary, lacrimal and sphenoid Inferior = maxillary and zygomatic
Which is the weakest border of the orbit?
Inferior
The optic canal lies in which bone?
Sphenoid
The SOF lies in which bone?
Sphenoid
The IOF lies in which bone?
Sphenoid
What runs through the optic canal?
Optic nerve
Ophthalmic artery
What runs through the SOF?
Branches of ophthalmic nerve (V1) Trochlear nerve Abducens nerve Branches of oculomotor Superior ophthlamic vein
What runs through the IOF?
Inferior ophthalmic vein
Which part of the eyeball is the iris?
Coloured part
Describe the lens of the eyeball
Focuses light onto back of retina
Held by suspensory ligaments attached to ciliary bodies
Relax and contract to focus the lens
What is the macula/fovea?
Area of most accurate vision
Well adapted to convert light energy to signals in the optic nerve
What is the optic disc?
The blind spot
Where the optic nerve enters the retina
What are the 3 broad layers of the eyeball?
Outer fibrous
Middle vascular
Inner - retina
Which parts of the eyeball make up the outer fibrous layer?
Sclera
Cornea
(Continuous)
What is the role of the outer fibrous layer of eyeball?
Maintains shape of eyeball
What parts of the eyeball make up the middle vascular layer?
Iris
Ciliary body
Choroid
Which part of the eyeball contains all the light cells?
Retina
Where do all the arteries and veins come in and out of the eyeball?
Optic disc
Where is the optic disc in relation to the fovea?
Optic disc is always on the nasal side
Fovea lateral to this
Describe retinal detachment
Can see tears/retina has moved down Can have surgery to reattach If left without a blood supply for too long then will not heal Partial/total blindness can follow Following high impact to face
What are the 3 meningeal layers?
Dura matter
Arachnoid matter
Pia matter
Why do we get photophobia with meningitis?
The optic nerve is a continuation of the brain
Has the same meningeal layers
Therefore inflammation occurs around the nerve
How many segments of the eye are there and what are they called?
2
Anterior and posterior
What is found within the posterior segment of the eye?
Vitreous body
Keeps shape
What is found within the anterior segment of the eye?
Anterior and posterior chambers
Both contain aqueous humor
Split by iris
Why do we have aqueous humor in the eye?
Lens is avascular
This is how it gets nutrients
How does aqueous humor drain?
Via trabecular meshwork
Into veins
Constant flow
Describe open angle glaucoma
Blockage in the meshwork
Aqueous humor build up
Anterior chamber becomes more distended - angle between cornea and iris gets bigger
Comes on slowly
What are cataracts?
When the lens becomes more and more opaque
What are the actions of superior and inferior oblique?
Superior - allows us to look down when looking medially
Inferior - allows us to look up when looking medially
Describe a blow out fracture
High impact to eye breaks inferior border
Contents of orbit drop down - tear drop sign on CT
Blood can collect in maxillary sinus
Cannot look up with affected eye because inferior rectus stuck - tethered down
Describe blood supply to the eye
Ophthalmic artery (from ICA)
Gives rise to central retinal artery - travels with optic nerve
End arteries
How does occlusion appear on an ophthalmoscope?
Seen as a cherry red spot on a pale background
Describe the venous drainage of the eye
Central retinal vein > superior ophthalmic vein > cavernous sinus
What is the conjunctiva?
A thin, clear film on top of everything else in the eye
Describe conjunctivitis
Inflammation, redness and watering of eye
Can be bacterial or viral
Very common
Give eyedrops to treat
What are the functions of the eyelid?
Protect from injury, excessive light and dryness
What are the 2 parts of the conjunctiva?
Bulbar = covers eyeball itself Palpebral = covers inner surfaces of the eyelids
What is the main muscle for opening the eye?
Levator palpebrae superioris
What are tarsal glands?
In the eyelid
Sebaceous gland - oily
Can get cysts/swellings
What are ciliary glands?
Base of eyelashes - secrete lipid to help prevent evaporation
Can get blocked = stye
How do you treat a stye?
Some need Abx
Others just warm, salty water
Which nerve innervates levator palpebrae superioris?
Oculomotor (III)
What is the palpebral fissure?
The opening between the eyelids
What is the lacrimal punctum?
Small openings at medial eye to collect tears
What is the limbus of the eye?
Border of the coloured part of the eye
Junction of cornea and sclerae
What is the choroid?
Pigmented vascular layer of eyeball between retina and sclerae
Contains CT
Melanin helps choroid limit uncontrolled reflection in the eye
How do we test visual acuity?
(Optic nerve) Wear glasses if needed, assess each eye Near vision - record smallest print can read Distance vision - Snellen chart Can test colours via Ichihara plate
How do we test visual field?
Test one eye at a time
Mirror the pt - you cover eye too
Test extremities of vision in an X - ask them to say yes when they see your finger wiggling
What is accommodation of the eyes?
Convergence of the eyes with pupillary constriction
Focusing on an object away and then close
Describe how we test the eye light reflex
Pupil constricts to light stimulus - consensual so happens in both eyes even though light directed at one
Rapid test - move light quickly between the two and pupils should not have time to dilate
What are the different limbs of light reflex?
Afferent = optic nerve Efferent = Oculomotor
Which nerves are you testing with eye movements?
III, IV and VI
How do we test eye movements?
One eye at a time, other covered
Make a H shape and ask them to follow with their eye - without moving head
