Clinical Pathologies of the Eye, Orbit, and Associated Stuctures Flashcards
What is the most common orbital wall fracture?
The floor (inferior wall)
How can the floor of the orbit fracture?
Following direct impact to the front of the eye
What is a fracture of the orbital floor known as?
An orbital blow out fracture
What is conjunctivitis?
When the conjunctivae becomes inflamed
What happens to the eye in conjunctivitis?
Blood vessels dilate and the eye appears red
What causes glaucoma?
Increased intra-ocular pressure due to the obstruction of drainage of aqueous humour
What are the types of glaucoma?
- Open-angle glaucoma
- Closed-angle glaucoma
What is the main risk factor for glaucoma?
Increasing age
What happens to glaucoma if left untreated?
Leads to irreversible damage and death of the optic nerve, causing impairment of vision and blindness
What is an open angle glaucoma caused by?
Blockage within trabecular meshwork, which drains into the canal of Schlemm
Describe the development of open-angle glaucoma
Develops painlessly and insidiously over time
What is the result of glaucoma developing painlessly and insidiously over time?
Can be difficult to pick up
What does treatment of open-angle glaucoma involve?
Topical medications (eye drops) that reduce the production of aqueous humour and/or increase its drainage
What medications are used in the treatment of open-angle glaucoma?
- ß-blockers
- Timolol
What may be required if the treatments for open-angle glaucoma fail?
Surgery; Trabeculectomy
When are signs of glaucoma screened for?
Opticians screen for signs during routine eye tests
How can a rise in intra-ocular pressure be detected?
By directing a brief puff of air against the front of the eye (cornea)
What signs of glaucoma can be detected on eye examination?
- Cupping of the optic disc
- Visual field loss
What is a closed-angle glaucoma?
When the irido-corneal angle is narrowed by the peripheral edge of the iris
What does closed-angle glaucoma?
Rapid rise in intra-ocular pressure
What is more common, open or closed angle glaucoma?
Open
Who is at most risk of closed angle glaucoma?
Long-sighted middle aged, or elderly people
What is true of the acute presentation of a closed-angle glaucoma?
It is an opthalmic emergency
Why is the acute presentation of a closed-angle glaucoma an opthalmic emergency?
It requires rapid recognition and management, as irreversible sight loss can occur within a few hours
How does a closed-angle glaucoma present?
- Sudden onset of a painful red eye
- Blurred vision or halos around objects
- Fixed or sluggish semi-dilated, often irregular, oval-shaped pupil
- Nausea and vomiting
What does the management of closed-angle glaucoma involve?
- Instilling muscarinic eye drops
- Strong analgesia
- Drugs to reduce intra-ocular pressure
While awaiting an emergency opthalmology opinion
What muscarinic eye drops can be used in closed-angle glaucoma?
Pilocarpine
When can cataracts occur?
As we age
What causes cataracts?
Degradation of proteins in the lens can cause it to become clouded and less transparent
How quickly do cataracts develop?
Gradually develop
What can cataracts cause?
Significant visual impairment
How can cataracts be treated?
Surgery
What is retinal detatchment?
When the retina begins to pull away from the blood vessels that supply it with oxygen and nutrients
What can cause retinal detatchment?
Due to age or trauma
Why can retinal detachment occur?
Occurs because sclera and choroid develop together, but the retina doesn’t, so it’s the first thing to tear off
What can happen if a retinal detachment is not caught early enough?
Can cause blindness
Why can retinal detachment cause blindness if not caught early enough?
Due to loss of blood supply to retina
What does a lesion of the oculomotor nerve affect?
Most of the extraocular muscles
What happens to the affected eye in an oculomotor nerve palsy?
The affected eye is displaced laterally and inferiorly
What muscle displaces the affected eye laterally in oculomotor nerve palsies?
Lateral rectus
What muscle displaces the affected eye inferiorly in oculomotor nerve palsies?
Superior oblique
What does a lesion of the trochlear nerve palsy affect?
Will paralyse superior oblique muscle
How does a trochlear nerve palsy present?
No obvious affect on the resting orientation of the eyeball, but patient will complain of diplopia and may develop a head tilt away from the site of lesion
What does a lesion of the abducens nerve cause?
Will paralyse the lateral rectus muscle
What happens to the affected eye in trochlear nerve palsies?
Affected eye will be adducted by the resting tone of the medial rectus
What is a style?
A small, painful cyst on the inside or outside of the eyelid
What is a stye usually caused by?
A bacterial infection
What does a stye usually affect?
One eye
Does a stye affect vision?
No
What are the main symptoms of a stye?
- Painful yellow lump on or in the eyelid
- Redness of eye or eyelid
- A watery eye, in some cases
What often happens with styes?
They get better withour treatment
What is a Meibomian cyst, or Chalazion?
A common condition caused by a blockage of a gland in the eyelid
Can Meibomian cysts get infected?
Rarely
How can Meibomian cysts be treated?
With injection, or removed with small operation
What are the symptoms of a Meibomian cyst?
- Small lump on eyelid
- Mild pain or irritation
What is papillodema?
An optic disc swelling that is caused by increased intracranial pressure
Give 5 examples of things that can cause raised intracranial pressure
- Brain tumour
- Hypotonia
- Tumours of the frontal lobe
- Glaucoma
- Local lesion
