Common conditions of the eye Flashcards
What is a hordeolum?
A hordeolum is a common disorder of the eyelid. It is an acute focal infection (usually staphylococcal) involving either the glands of Zeis or, less frequently, the meibomian glands
they can appear externally and internally
a
superior rectus
b
lateral rectus
c
inferior rectus
d
inferior oblique
e
medial rectus
f
superior oblique
What is conjunctiva
thin vascular membrane that covers inner surface of eyelids and loops back over sclera.
Does not cover the cornea
What is conjunctivitis, symptoms and treatment?
Self-limiting bacterial or viral infection of the conjunctiva
Red, watering eyes, discharge
No loss of vision as long as infection does not spread to cornea
Rx – antibiotic eye drops if likely to be bacterial
What are the 2 types of stye or hordeolum?
External – affecting the sebaceous glands of an eyelash
Internal – affecting the meibomian glands
Describe the histology of the cornea (5 layers)?
- Epithelium - stratified squamous non-keratinised
- Bowman’s membrane (basement membrane of corneal epithelium)
- Stroma - regularly arranged collagen, no blood vessels
- Descemet’s layer
- Endothelium – single layer (normal - 2500 cells/mm2) - shown by arrow
What are 2 types of pathology of the cornea?
- Inflammatory – eg: corneal ulcers
- Non-inflammatory – eg: dystrophies
What can corneal pathologies commonly lead to?
Corneal pathologies frequently lead to opacification of the cornea. This might need to be treated by corneal transplant - Keratoplasty
What may cause corneal ulcers?
Infectious - Viral/ bacterial/ fungal infection of cornea. Needs aggressive management to prevent spread, scarring
Non-infectious ulcers due to trauma, corneal degenerations or dystrophy
Non- Inflammatory dystrophies and degenerations are a group of diseases affecting the cornea which are what?
- Bilateral
- Opacifying
- Non – inflammatory
- Mostly genetically determined
- Sometimes due to accumulation of substances such as lipids within the cornea
What is the lcinical presentation of non- inflammatory dystrophies and degenerations
First to fourth decade
Most commonly - decreased vision
Start in one of the layers of the cornea and spread to the others
Is a corneal transplant easier or harder to carry out and why?
The avascularity of the cornea is of benefit to surgeons when performing a graft surgery as it means there is a lesser chance of foreign antigens from a corneal graft being recognised by the recipient, so lesser chance of a graft rejection
This has lead researchers to believe that the cornea is an “immune-privileged” site
(remember there are no lymphatics draining the eyeball; though lymph drains the eyelids)
What is the most common disease affecting the eye?
cataract
What is a cataract?
lens opacification
Why do cataracts develop?
Older (embryological, foetal) fibres are never shed - compacted in the middle
No blood supply to lens, which depends entirely on diffusion for nutrition
Absorbs harmful UV rays preventing them from damaging retina but in the process, get damaged themselves
Damaged lens fibres - opaque - CATARACT
WHat is the treatment of cataract?
Surgery – small day case – lens capsule opened – cataracteous lens removed by emulsification – plastic lens placed in capsular bag
Where does aqueous humor drain?
angle of the anterior chamber through the trabecular meshwork into schlemms canal
What is the 2nd global cause of blindness?
glaucoma
WHat is the most commonly seen form of glaucoma?
Most commonly seen form of primary glaucoma is Primary Open Angle Glaucoma (POAG)
What is glaucoma?
Raised intraocular pressure (IOP)
How does glaucoma present and how is it picked up?
Bilateral
Patient can be asymptomatic for a long period of time
Picked up on routine eye exams
What are the consequences of raised IOP?
Pressure on nerve fibres on surface of retina - die out - visual field defects
optic disc appears unhealthy, pale and cupped
This results in altered field of vision
Ultimately all nerve fibres are lost, which results in blindness
What is the triad of signs for the diagnosis of glaucoma?
What is the management of POAG?
Eye drops to decrease IOP
Prostaglandin analogues
Beta-blockers
Carbonic anhydrase inhibitors
Laser trabeculoplasty - used when eye drops are not working
Trabeculectomy surgery
What is experienced in angle closure glaucoma?
Sudden onset, painful, vision lost/ blurred; headaches (often confused with migraine)
O/E – Red eye, cornea often opaque as raised IOP drives fluid into cornea
AC shallow, and angle is closed
Pupil mid-dilated
IOP severely raised
pictures:
Right eye: red and inflammed, cornea hazy, pupil mid-dilated
Slit-lamp photo showing shallow AC compared to normal AC
Why does the angle close?
Functional block in a small eye – large lens
Mid-dilated pupil - periphery of iris crowds around angle and outflow is obstructed
Iris sticks to pupillary border (synechia) which prevents reaching AC. Leads to iris balooning anteriorly and obstructing angle
What is the management of an acute eye episode?
- Decrease IOP
IV infusion with or without oral therapy – carbonic anhydrase inhibitors (acetazolamide)
Analgesics (reduce pain), antiemetics (reduce naeusa and vomiting)
Constrictor eye drops – pilocarpine
If no contraindication beta-blocker drops such as timolol
Steroid eye drops (dexamethasone)
2.Iridotomy (laser) - both eyes - to bypass blockage
What is the difference between open angle and angle closure glaucoma?
open angle - gradual, painless build up of pressure
closed angle - suddent increase in IOP leading to red eye, severe pain and patient usually presents as an emergency
What is Uveitis?
inflammation of uvea
What are the different types of uveitis?
Anterior uveitis - iris with or without ciliary body inflammed
Intermediate uveitis - ciliary body inflammed
Posterior uveitis - choroid inflammed
What are the causes of uveitis?
Isolated illness
Non-infectious autoimmune causes - eg: presence of HLA-B27 predisposes to anterior uveitis
Infectious causes - chronic diseases such as TB
Associated with systemic diseases - eg: ankylosing spondylosis
What is the pathophysiology of anterior uveitis?
An inflammed anterior uvea (iris) leaks plasma and white blood cells into the aqueous humor
These are seen during slit lamp examination as a hazy anterior chamber and cells deposited at the back of the cornea
The eye is red, painful, with visual loss
Cells in the AC may settle inferiorly – “hypopyon
What happens in intermediate uveitis?
In intermediate uveitis the ciliary body is inflammed and leaks cells and proteins.
This leads to a hazy vitreous
Patient complains of “floaters” or hazy vision
What happens in posterior uveitis?
In posterior uveitis the choroid is inflammed
Since the choroid sits under the retina, the inflammation frequently spreads to the retina causing blurred vision
