How wide is the eye in diameter?
2.5 cm
Which eyelid is the most important one clinically?
Upper eyelid
Lower eyelid has very little function in comparison
Which type of gland is found within the tarsal plates and releases an oily substance which stops the tear film from evaporating?
Tarsal gland
or Meibomian gland
What muscles open the upper eyelid?
Levator palpebrae superioris
AND
Mueller’s muscle
Which type of fibres innervate Mueller’s muscle so it can help levator palpebrae superioris with opening the upper eyelid?
Sympathetic
Which cranial nerve innervates levator palpebrae superioris?
CN III
What is the function of orbicularis oculi?
Which cranial nerve supplies it?
Closes the eyelids
CN VII (remember it’s a muscle of facial expression)
Which part of orbicularis oculi is responsible for blinking?
Palpebral part
What are the three main symptoms of Horner’s syndrome?
Miosis (constricted pupil)
Ptosis (droopy eyelid)
Anhidrosis (lack of sweating)
unilaterally
What lung tumour can cause Horner’s syndrome by compressing the superior cervical ganglia?
Pancoast tumour
What is the purpose of the orbital septum?
Prevents transmission of pathogens/debris etc. into bony orbit
What is an infection of the orbit which is sight and life-threatening and must be treated immediately?
Orbital cellulitis
What does orbital cellulitis look like?
Puffy inflamed eye
Fever
Rigors
Pupillary disorders
Where in the orbit is the lacrimal gland found?
Superolaterally
Where are the Meibomian glands found?
Tarsal plates
Lacrimal fluid is swept from the ___ to ___ sides of the eye.
temporal to nasal
What is the function of the Meibomian glands?
Add oil to tear film to stop it from evaporating
Through which structures does lacrimal fluid enter the superior and inferior lacrimal papillae?
Puncta
What carries lacrimal fluid from the lacrimal sac to the nose?
Nasolacrimal ducts
What symptom may be produced by a blind-ended lacrimal sac?
Watery eyes
which AREN’T red (no inflammation)
Which type of weather dries out the eyes?
What symptom does this lead to?
Cold weather
Watery eyes - reflex lacrimation overcompensates
Which cranial nerves control the
a) sensory
b) motor parts of reflex lacrimation?
Is this sympathetic or parasympathetic?
a) CN V1
b) CN VII
Parasympathetic
Why do people with uncontrolled diabetes develop corneal ulcers?
Neuropathy
CN V1 doesn’t detect dryness
So reflex lacrimation doesn’t occur
So cornea dries out and ulcerates
Which enzymes are found in the tear film and give it antibacterial properties?
Lysozymes
Which types of conjunctiva line
a) the sclera of the eyes
b) the inner surface of eyelids?
What are the folds which form when these two types make contact?
a) Bulbar conjunctiva
b) Palpebral conjunctiva
Conjunctival fornix
The palpebral conjunctiva lines the ___.
The bulbar conjunctiva lines the ___.
inner eyelid
sclera
Which type of conjunctiva is more vascular?
Palpebral conjunctiva
What can be seen on the palpebral conjunctiva?
Follicles
Papillae
What does
a) bacterial
b) viral
conjunctivitis look like?
a) Pus, red eye
b) Watery, pink eye
Viral conjunctivitis commonly accompanies which type of infection?
URTI
Which lymph nodes may be enlarged in conjunctivitis?
Pre-auricular lymph nodes
Conjunctivitis is highly ___.
contagious
Follicles may be seen on the inner eyelid in which types of infection?
Bacterial - esp. chlamydia
Viral
Papillae are commonly seen on the inner eyelid in ___ reactions.
allergic
What percentages of total refractive power do the
a) cornea
b) lens
have?
a) 2/3rds
b) 1/3rd
The epithelium of the cornea (regenerates / can’t regenerate) and has loads of nerve endings.
epithelium regenerates
What is the endothelium of the cornea like?
Does it regenerate?
Single layer of cells
Doesn’t regenerate
What disease causes the cornea to bulge into a cone shape and causes visual disturbance?
Keratoconus
The anterior surface of the lens is ___.
The posterior surface of the lens is ___.
anterior surface is FLAT
posterior surface is CURVED
What disease causes the lens to become yellow and difficult to see through?
Cataracts
How are cataracts treated?
Implant artificial lens
Which muscles control the shape of the lens?
Ciliary muscles
Sympathetic stimulation causes:
ciliary muscles to CONTRACT / RELAX
the lens to FLATTEN / BULGE
NEAR SIGHT / FAR SIGHT
Sympathetic:
ciliary muscles RELAX
lens FLATTENS (to be CONCAVE)
FAR SIGHT
Parasympathetic stimulation causes:
ciliary muscles to CONTRACT / RELAX
lens FLATTENS / BULGES
NEAR SIGHT / FAR SIGHT
Parasympathetic:
ciliary muscles CONTRACT
lens BULGES (to be CONVEX)
NEAR SIGHT
What structures are in the vascular layer (uvea)?
Iris
Ciliary body
Choroid
The choroid supplies ___ to the other layers of the uvea.
nutrition
The uvea is ___ to help with light capture.
pigmented
Where is aqueous fluid produced?
Where can it be reabsorbed from?
Ciliary body
Bloodstream
What colour is aqueous fluid?
Transparent
Aqueous fluid has a (high / low) protein content.
low protein content
so it can be transparent to see through
Why might the aqeuous fluid become hard to see through?
Uveitis - full of floating inflammatory cells
Treat with steroids
Aqueous fluid is produced by the ___ ___, fills the (anterior / posterior) chamber and then drains where?
ciliary body
anterior chamber
iridocorneal angle
The iridocorneal angle is found at the (superior / inferior) part of the cornea.
superior
What is the normal range of intraocular pressures?
12 - 22 mmHg
In which disease is intraocular pressure raised?
Glaucoma
What is the path that nerve impulses take in the pupillary light reflex?
Optic nerve
Optic chiasm
Optic tract
Optic radiation
Pretectal nucleus of visual cortex
EW nucleus
Short ciliary nerve
Sphincter pupillae
Once they have come off the spinal cord at L2, how do sympathetic nerves reach the eye?
Sympathetic chain
Superior cervical ganglia
Internal carotid artery
Ophthalmic artery
Long ciliary nerves
Dilator pupillae
What is the accommodation reflex?
Eyes focus on object coming towards you in the midline
Which three actions allow for the accomodation reflex and which muscles control them?
1. Adduction of eyes by medial rectus (CN III)
2. Constriction of pupils by sphincter pupillae
3. Flattening of lens by ciliary muscles
What is myopia?
Short sightedness
What causes myopia?
Eye is too wide so light isn’t focused onto retina correctly
Myopia (short sightedness) increases your chances of what?
Retinal detachment
Which extraocular muscles does CN III control?
Medial rectus
Superior rectus
Inferior rectus
Inferior oblique
Levator palpebrae superioris
What sort of eye movement does a CN III palsy cause?
DOWN AND OUT
because lateral rectus (abduction) and superior oblique (depression) are the only muscles still working
What sort of eye movement problems does CN IV palsy cause?
UP AND IN
with a head tilt required to see properly
What might a person with CN IV palsy have trouble doing?
Walking down stairs
due to diplopia (double vision), they can’t look down properly
CN IV palsy produces symptoms in the (ipsilateral / contralateral) eye.
contralateral eye
because they arise from the brainstem and then cross over
What does CN V1 supply?
Forehead
Upper eyelid
Eye
TIP OF NOSE
What is a sign that ophthalmic zoster may affect the cornea?
Hutchison’s sign
Rash on tip of nose (which is supplied by CN V1)
Why do people with viral keratitis have dendritic ulcers?
Virus tracks along CN V1
What eye movement does CN VI palsy cause?
Medial squint
because CN VI supplies lateral rectus only
What is the common origin for all the extraocular muscles?
Common tendinous ring
The common tendinous ring is part of the sheathe for which nerve?
Optic nerve
What nerve problem causes pain on eye movement?
Optic neuritis
because common tendinous ring is part of nerve sheathe
What type of fracture can trap inferior rectus?
Orbital blowout fracture
How would a suspected orbital blowout fracture be investigated?
CT head
because CT is good for bones
An orbital blowout fracture can breach which wall of the bony orbit?
What is a complication of this?
Medial wall
Transmission of bacteria into maxillary sinus > meningitis
Where in the retina are
a) rods
b) cones found?
a) Rods - peripheral
b) Cones - central (macula/fovea)
Which type of photoreceptor is good for detecting movement?
Rods
high sensitivity (see other lectures)
Where exactly is the blind spot?
15 degrees temporal from centre
What does someone mean when they say the retina is inverted?
Light passes through the blood vessels, ciliary axons / ganglia to reach the photoreceptors
Then the nerve impulses travel anteriorly through all that to the optic nerve
What are the end arteries of the eye?
Central artery of the retina
(ophthalmic artery)
What do veins look like through an ophthalmoscope?
Thick and dark
because they have no muscle
What do arteries look like through an ophthalmoscope?
Thin, tubular, lighter
because they have muscular walls
What are the 3 Cs to look for when describing the optic disc?
CUP - inner ring (like a donut)
COLOUR - should be pink/orange
CONTOUR - should be well-defined
What colour does the
a) whole fundus
b) fovea
turn in a central retinal artery occlusion?
a) Milky white
b) Cherry red / black
Where does
a) CN III, IV and VI enter the orbit
b) the superior ophthalmic vein exit the orbit?
Superior orbital fissure
Where do the ophthalmic veins drain after exiting the bony orbit?
Cavernous sinus
What does the fundus look like in a central retinal vein occlusion?
Pizza
