Common Conditions of the Eye Flashcards
List of conditions contained within
- Blow Out Fracture
- Orbital Fat Hypertrophy
- Cavernous Sinus Infection
- Colobona
- Retinal Detachment
- Conjunctivitis
- Ptosis
- Inability to close the eye
- Stye
- Corneal ulcer & Dystrophy
- Cataract
- Glaucoma
- Uveitis
How does a blow out fracture occur?
The rim of the orbit is very strong so it tends not to fracture.
On blunt force trauma the force can be transmitted to the walls/floor of the orbit causing fractures of the weaker bones there
What might be the consequences of a blow out fracture to the orbital floor?
- Reduced sensation of the infra-orbital nerve coming out the infra-orbital foramen
- Inability to elevate the eye as the muscles are tethered through the fracture into the maxillary sinus
- Double Vision (because the eye cant move and match the other properly)
What could cause the orbital fat to hypertrophy?
some conditions such as thyroid disease.
How would you see orbital fat hypertrophy?
The staring appearance.
This is obvious as the corneoscleral junction will visible above & below whereas it should normally be covered above and in contact with the eyelid below.
Also some inflammation of the sclera
How could cavernous sinus thrombosis occur?
An infection could spread through the valveless emissary veins to the cavernous sinus, spread there and lead to thrombosis
How would a cavernous sinus thrombosis present?
The eye would be swollen, red and painful from build up of venous blood.
There would also be reduced eye movement and blurred/lost vision.
You could see swollen veins on an ophthalmoscope
What muscle disorder could cause your eye to drift upward in the adducted position?
The obliques handle elevation/depression in the adducted position.
If the sup oblique is paralysed then the normal balance between it and the inf would be out. Causing the inf to elevate the eye when its adducted.
Describe the embryological growth of the eye?
Optic Vesicle grows outward from diencephalic part of the neural tube –> Optic Cup
Ectoderm invaginates –> Lens vesicle
What is a coloboma?
A hole in a part of the eye e.g. Iris/retina/optic disc in the shape of a keyhole.
Caused by failure of the choroidal fissure to close during embryological development
At what layer does a retinal detachment occur?
At the potential space between the 9th and 10th layers of the retina
How do blunt trauma retinal detachments occur?
The force of the trauma is transmitted to the eye and it causes peripheral tears in the retina and liquidation of the vitreous gel.
Then the liquid vitreous gel pushes through the retinal tear and causes it to detach
What is the conjunctiva?
A thin vascular membrane covering the inner surface of the eyelid and the sclera (but not the cornea)
How does conjunctivitis present?
- Red/pink conjunctiva
- Pussy Discharge
- Eyelids stick together
- Vision unaffected
If you get conjunctivitis with vision loss whats happened?
The inflammation has spread from the conjunctiva to the cornea
How do we treat conjunctivitis?
Usually its self limiting
But if its bacterial (opposed to viral) we can use antibiotic eyedrops
Define Ptosis and its cause?
Drooping of the Eyelid
Usually due to paralysis of the Levator Palpebrae Superioris or damage to the oculomotor nerve.
What could cause an inability to close the eyelid?
Paralysis of the facial nerve, often comes with an ear infection
What happens to the eye if you cant close your eyelid?
The cornea dries out and ulcerates.
This is especially bad when your asleep
Define a Stye/Hordeolum?
A small painful lump on the inside or outside of the eyelid, usually a pus filled abscess from a bacterial infection
What are the types of stye?
External Stye (Or Hordeolum Externum) - Due to blockage of sebaceous glands at the base of the eyelashes
Internal Stye (Or Hordeolum Internum) - Blockage of meibomian glands in the tarsal plate
What do meibomian glands do?
They’re in the tarsal plate of the eyelid
They make the oily layer of tear film
How do we treat a Stye?
Warm compress
Eyelid Hygiene
May need surgical incision and curettage (scooping out)
(An external Stye may be solved by removing the affected lash)
What are the causes of corneal ulcers?
Inflammatory:
Infection
Trauma
Non-inflammatory:
Degenerative or dystrophy
What sets corneal dystrophy apart from other corneal disorders?
- Bilateral
- Opacifying & decrease vision
- Non-inflammatory
- Most genetically determined and down to accumulation of substances e.g. lipids
- Tends to start in layer 1 and spread to rest of cornea
Why is it easier to do a corneal transplant than any other?
The cornea is avascular
Therefore its less likely the body will notice and react to the foreign antigens of the transplant.
Therefore you don’t need the same degree of antigen matching and rejection is less common leading to it being called an “immune privileged” site
How does a primary cataract develop?
Damaged/old lens fibres dont shed, instead they are compacted in the middle of the lens.
Combined with absorbing harmful UV rays in order to protect the retina this leads to opacification.
What do we call an immature cataract?
An immature cortical cataract
What could cause a secondary cataract?
- Steroid induced
- Nuclear Sclerosis (age-related compaction of old lens fibers in the nucleus)
- Sutural + Zonular Cataracts (congenital, opacification occurs in utero)
What would you do to take a look at a cataract?
Use sympathetic eye drops to trigger pupil dilation.
The cataract is much easier to see this way
How would you treat a cataract?
Surgical replacement of the cataractous lens with a plastic one
What is a glaucoma/how do we diagnose it?
It is essentially raised intraocular pressure causing vision loss.
Diagnosed by a triad of signs:
- Raised IOP
- Visual field Defects
- Optic Disc changes on Ophthalmoscopy
How can we treat a POAG?
Eye drops to lower IOP:
- Prostaglandin analogues (Increase Aqueous humor drainage)
- Beta Blockers (Decrease Aqueous humor production)
- Carbonic Anhydrase Inhibitors (Blocks water entering eye -> decreased aqueous humour production)
Laser Trabeculoplasty
Trabeculectomy Surgery
How does a trabeculectomy help with glaucoma?
Removing part of the trabecular meshwork and associated structures allows the eye to drain and IOP lowers
What are the two main types of glaucoma?
Primary Open Angle Glaucoma (POAG)
Angle Closure Glaucoma
How do the different types of glaucoma present?
POAG:
- The angle is open
- Slow progression & may be asymptomatic for a long time
- Progressively worse visual field defects till you go blind
Angle Closure Glaucoma:
- Sudden Onset
- Comes with other symptoms like pain, headaches, red eye
- The ant chamber is shallow and the angle is closed (visible on slit lamp investigation)
- The pupil is mid dilated
What causes the different types of glaucoma?
A POAG is due to slowly raised IOP.
Puts pressure on nerve fibres in the retinal surface and the optic nerve head
This kills the fibres and makes the optic disc unhealthy, pale and cupped (visible on ophthalmoscopy)
Both trigger worsening visual field defects till you go blind.
Angle Closure Glaucoma:
- Some event causes peripheral iris to block the angle preventing aqueous humor drainage
- Causes Sudden severe spike in IOP
- Drives fluid into the cornea causing most of the symptoms
How would we manage an Angle Closure Glaucoma? Remember its an acute emergency presentation
Analgesia
Lower IOP:
- IV +/- oral Carbonic anhydrase inhibitors
- Beta blocker eyedrops
- Steroid eye drops
- Constricter eyedrops (muscarinic agonist)
Also laser Iridotomy
Define the Uvea
The middle vascular layer of the eyeball (Ciliary body, Iris & Choroid)
What are the types of uveitis?
Anterior - Iris
Intermediate - Ciliary Body
Posterior - Choroid
What causes Uveitis?
- Isolated
- Infectious e.g. TB
- Systemic e.g. Ankylosing Spondylosis
- Auto-immune (predisposed to ant uveitis if you have HLA-B27 gene)
What are the signs of anterior uveitis?
inflammatory/plasma cells leak into aqueous humor so you can see them:
- Settled inferiorly in the ant chamber (Called Hypopyon)
- Floating in the anterior chamber on slit lamp exam
What sets intermediate uveitis apart?
Cells leaked from the inflamed ciliary body make the vitreous gel go hazy.
The patient gets hazy vision or “floaters”
Whats different about posterior uveitis?
The choroid is inflamed which can cause blurred vision by spreading to the retina
