Ophthamology - The Red Eye Flashcards
Is acute angle closure glaucoma an emergency?
YES
define glaucoma
a condition of increased pressure within the eyeball, causing gradual loss of sight.
what is acute angle closure glaucoma (AACG)?
A rapid rise in intraocular pressure due to sudden obstruction to the flow of aqueous humour in the eye
What is aqueous humour produced by?
Ciliary body
Function of aqueous humour?
- Maintains pressure & shape of eye
- Supplies nutrients to cornea & lens
Describe the course of flow of aqueous humour
- Produced by ciliary body
- Flows through pupil into anterior chamber (between iris and cornea)
- Drains into the trabecular meshwork to exit the eye (via canal of Schlemm)
How does AACG occur?
- Iris is pushed/pulled forward to obstruct the trabecular meshwork (pupillary block)
- Aqueous humour cannot drain from eye due to anterior chamber narrowing
- Pressure inside eye rapidly increases
- Compression of optic nerve and visual loss (optic nerve damage)
Risk factors for AACG?
- FH
- Female sex (4x)
- Older age
- Ethnicity - Asian
- Anatomical predisposition
- Pupil mid-dilation
are males or females more prone to AACG?
Females (4x)
What ethnicity is most prone to AACG?
Asian
What anatomical features can predispose you to AACG?
- Short eyeball length
- Long sightedness (hypermetropia)
Define hypermetropia
Long-sightedness
How can pupil mid dilation lead to AACG?
When the pupil is mid-dilated, the distance between the iris and the lens is the shortest, and the two structures can come into contact with each other in individuals at risk for angle closure.
e.g. dark room, medications
What medications can lead to pupil mid dilation?
- Anticholinergics (e.g. oxybutynin)
- Pupil dilating drops (e.g. atropine)
Complications of AACG?
- Permanent vision loss
- Central retinal artery or vein occlusion
- Repeated episodes of AACG
Symptoms of AACG?
ACAG is an important differential to consider in anyone presenting with a painful red eye.
- Very painful eye
- Blurred vision/halo around lights
- Headache (not relieved by simple analgesia)
- Vomiting
- Watery eyes
- Ask about medication history – drugs than can cause pupillary dilation
Signs of AACG?
- Unilateral red eye
- Fixed mid-dilated pupil – does not react to light
- Globe (eyeball) – will feel hard to touch
- Corneal oedema – cloudy cornea (later sign)
What 2 main investigations are used in AACG?
- Tonometry
- Gonioscopy
Which investigation measures angle between iris & cornea?
gonioscopy
Which investigation measures intraocular pressure?
tonometry
What is the aim of initial management of AACP?
Reduce intraocular pressure!
Which 2 medications can be used to reduce IOP in AACG?
- Pilocarpine eye drops
- Acetazolamide
Function of acetazolamide
to reduce production of aqueous humour
Definitive management of AACG?
Bilateral laser iridotomy –laser makes hole in iris to improve aqueous humour outflow
What should be avoided in patients with AACG history?
Avoid dark rooms and eye patches as this may worsen angle closure by causing mid-dilation of pupils
Differentials for a painful red eye?
- Acute angle closure glaucoma
- Scleritis
- Uveitis
- Corneal abrasion
- Episcleritis
- Corneal ulcer
Chemical eye injuries can be accidental or deliberate. What are some examples of some ‘accidental’ causes?
- Cement
- Plaster
- Household cleaners
- Industrial substances
Chemical eye injuries can be accidental or deliberate. What are some examples of some ‘deliberate’ causes?
- Ammonia
- Strong acids
Do alkalis or acids cause more severe eye injuries? Why?
Alkalis → they can liquefactive necrosis as they propagate themselves deeper into the eye, whereas acids cause coagulative necrosis and impede their own progress
What type of necrosis do alkalis cause in the eye?
Liquefactive
What type of necrosis do acids cause in the eye?
Coagulative necrosis
Symptoms of chemical eye injuries?
- Severe eye pain and watering
- Reduced visual acuity
- Skin burns – erythema, blistering
Signs seen in chemical eye injuries?
- Corneal abrasion/large epithelial deficits
- Associated skin damage
- Blanching of the limbus (the joint between the conjunctiva and cornea) which is important prognostically
Most important management step in chemical eye injuries?
Irrigate!!
Give some medications used in the treatment of chemical eye injuries and their purpose
- Topical steroids (e.g. prednisolone) → reduce inflammation
- Antibiotics (e.g. chloramphenical) → prevent 2ary infection
- Cytoplegics (e.g. cyclopentolate) → paralyse the iris and help reduce pain
- Citric and ascorbic acid → helps with healing
- Analgesia
What is chloramphenicol?
A topical eye ointment used to treatment of conjunctivitis and chemical burns
What is conjunctivitis?
Inflammation of the conjunctiva (the external layer covering the outer surface of the globe and inner surface of the eyelids)
What is the conjunctiva?
the external layer covering the outer surface of the globe and inner surface of the eyelids
How common is conjunctivitis?
Extremely common, accounts for 1% of GP consultations in UK.
Define chemosis
Swelling of conjunctiva
Define epiphora
watering eyes
What are the 3 main types of conjunctivitis?
- Bacterial (infectious)
- Viral (infectious)
- Allergic (non-infectious)
What is the most common cause of viral conjunctivitis?
Adenovirus
Transmission of viral conjunctivitis?
Extremely infectious → direct contact with contaminated skin or objects can lead to spread
Does viral conjunctivitis tend to be unilateral or bilateral?
Bilateral
Describe the discharge in viral conjunctivitis
Profuse and watery
Does tender preauricular lymphadenopathy tend to be present in viral or bacterial conjunctivitis?
viral
Is a concurrent URT infection typically seen in viral or bacterial conjunctivitis?
Viral