What is ptosis?
Top eyelid drooping
What may ptosis cause in children left untreated?
- Amblyopia (lazy eye)
- Permanently reduced vision due to inability to properly develop
What is the name of the glands embedded in the tarsal plates of the tarsus?
Meibomian glands
(20-25 in total)
What do Meibomian glands secrete?
Oily substance
Which muscles are involved in opening the eyelid?
- Levator palpebrae superioris
- Muller’s muscle (superior tarsal muscle)
Which nerve is responsbile for providing motor innervation to the following muscles?
a) Levator palpebrae superioris
b) Superior tarsal muscle
a) Oculomotor (CN III)
b) Sympathetic control
Which muscle is involved in closing the eye and which nerve is it controlled by?
Orbicularis oculi
CN VII (facial nerve)
Horner’s syndrome is a triad of which three things?
- Anhydrosis
- Miosis
- Ptosis
Orbital cellulitis is often bilateral
True or false?
False
It is much more often unilateral
What does orbital cellulitis look like superficially?
- Unilateral erythema
- Defined orbital redness
- Difficult eye movements
- Pupil problems
Why is dry eyes a common problem in autoimmune conditions?
Lacrimal gland ducts can easily scar
Why may watery eyes be treated with lubricant?
Watery eyes may be caused by dry eyes which become watery due to overcompensation
What are the 3 layers of the tear film?
- Lipid phase
- Aqueous phase
- Mucus phase
(all sit above epithelium)
Which nerve is responsible for inducing the reflex for tear production?
Trigeminal nerve
Which nerve senses dry eyes and signals for tear production?
Trigeminal nerve
Which nerve causes tear production?
Facial nerve parasympathetic nerve fibres
Which type of conjunctiva lines
a) Inner eyelids
b) Eyeball
a) Palpebrae
b) Bulbar
What is special about the tissues forming the conjunctiva?
They are excellent at healing
How can the cornea be oxygenated anteriorly?
- Oxygen from air
- Palpebral conjunctiva is highly vascularised and allows oxygenation when eyes are closed
How does viral conjunctivitis present?
- Pinkish-red eyes
- Watery eyes/syrupy secretion
- Round bumps (rice grain) on lower fornix
In viral conjunctivitis, what does it suggest if the round bumps (rice grain) on lower fornix are
a) Bilateral
b) Unilateral
a) Adenoviral cause
b) Chlamydial cause
What are the three main layers of the cornea?
- Epithelium
- Stroma
- Endothelium
How quiickly does the corneal epithelium turnover?
48hrs
The endothelium of the cornea is _______ replaced
The endothelium of the cornea is never replaced
Why is the cornea transparent?
Collagen fibres are well organised and regularly spaced
Why is the development of cataracts at the back of the lens worse than at the front?
This is where light is focussed
How is the lens attached to the ciliary body?
Zonules
Why does the ability to focus between far and near objects reduce with age?
Lens fibres have poor regenerating
What are the two different aspects of the lens called?
- Outer part - Cortex
- Inner part - Nucleus
What comrpises the uvea?
- Iris
- Ciliary body
- Choroid
What are the main roles of the uvea?
- Absorbing reflected light into the eye
- Providing nutritional support to eye structures
Where does aqueous humour drain?
Scleral venous sinus
(Canal of Schlemm)
Where is aqueous humour secreted?
Ciliary processes
What are two key signs on a slit lamp view of the eye for uveitis?
- Floating cells (like dust particles)
- Flare (like smoke)
How will the eye be positioned in a complete third nerve palsy?
Down and out with ptosis
Why is the trochlear nerve unique?
Arises from dorsal aspet of brainstem and crosses over
Where does the trochlear nerve enter the orbit?
Superior orbital fissue
What does the abducens nerve supply?
Motor innervation to the lateral rectus
Where does the abducens nerve pass into the orbit?
Middle of the cavernous sinus
When may an abducens nerve palsy occur?
Raised ICP
Where does the abducens nerve originate?
Pons
Why does optic neuritis cause pain on eye movements?
Optic nerve sheath is attached to the common tendinous ring
Typically, a blow-out fracture will entrap which muscle?
Inferior rectus
Where are cone cells found in their highest density?
Fovea
The retina has which type of epithelium?
Cuboidal
By how mnay degrees is the blind spot located temporally in the visual field?
15
How may a patient describe a retinal detachment?
- Flashes of light
- Curtainscoming down
- Floaters
- Painless