Eyes Flashcards
What are the Red flag symptoms for eye pathology?
Red eye
Sudden vision loss
Eye pain
What does a red eye suggest?
Disorder may be ocular rather than referred
What aspects of Hx are important in eye pathology?
Contact lenses Visual aids Similar episodes of eye problems Eye surgery and lazy eye Social Hx: helps determine extent of vision loss
What visual examinations can be assessed?
Snellen chart: visual acuity in adults
Sheridan-Gardiner test: visual acuity in children
Ishihara test: colour blindness
How is a Snellen chart result determined?
Two consecutive incorrect letters, use result above
If the patient is illiterate, how is visual acuity assessed?
Counting fingers
Presence/absence of light
Which ophthalmic medical emergency can occur due to Staph aureus?
Orbital cellulitis
Name other common causes of orbital cellulitis
Strep pneumoniae
Strep pyogenes
H influenzae
MRSA
Why is orbital cellulitis considered a medical emergency?
It is potentially sight-threatening and life-threatening
What are the characteristic features of orbital cellulitis?
Acute onset of unilateral eyelid oedema and chemosis (conjunctiva oedema), with erythema
Orbital signs: proptosis, gaze restriction, blurred/double vision
Systemic signs: fever, severe malaise
What features occur in preseptal cellulitis?
Acute onset of eyelid oedema and erythema
Absence of orbital signs
Fever, malaise
Ptosis
Although orbital cellulitis affects all ages, which is the commonest?
Children
What is the difference between preseptal cellulitis and orbital cellulitis?
Preseptal cellulitis is commoner and less serious.
Rarely involves postseptal anatomy.
Examination: eyelid oedema in absence of orbital signs.
What are the most important predisposing factors for preseptal (periocular) infection in children?
URTI
Sinusitis
What is the orbital septum?
A membranous sheet acting as the anterior boundary of the orbit. Separates the eyelid from the contents of the orbital cavity. Provides a barrier between the preseptal space and the orbit.
Outline the pathophysiology of orbital cellulitis
- Spread of infection from preorbital structures (sinuses, face, eye globe, lacrimal sac, dental via maximally sinus). Commonest cause.
- Spread of preseptal cellulitis
- Post-surgery
- Haematogenous spread
Outline the pathophysiology of preseptal cellulitis
- Local skin trauma
- Spread of local infection (sinuses, stye, lacrimal sac)
- Spread of distant infection from face or URT
What are some complications of orbital cellulitis?
Total vision loss
-Exposure keratotomy - permenant damage to cornea
-Raised intraocular pressure
-Central retinal artery or vein occlusion
-Optic neuropathy
Meningitis (rare)
Cerebral abscess (rare)
Early presentation of preseptal and orbital cellulitis is similar. What features increase suspicion of orbital cellulitis?
Proptosis
External ophthalmoplegia (paralysis of extraocular muscles)
Decreased visual acuity (impaired colour vision is an early sign)
Chemosis
What situations require an emergency referral to ophthalmology?
Children with suspected preseptal cellulitis (considered orbital cellulitis until disproven)
Suspected orbital cellulitis
Patients with features of preseptal or orbital cellulitis who are systemically unwell
If not responding to treatment for preseptal cellulitis
If lid abscess drainage is required
Doubt over diagnosis
Outline the management of preseptal cellulitis
Co-amoxiclav: should improve in 24-48hr
IV ABX e.g. Ceftriaxone
ENT referral if sinusitis present
How is orbital cellulitis disproven in children with signs of preseptal cellulitis?
Repeat examinations normal
Good response to ABX in first 24hr
Normal CT scan
Outline the management of orbital cellulitis
Required hospital admission for 7-10 days
IV ABX
Metronidazole in pt over 10yr with chronic sinonasal disease
Clindamycin + quinolone if penicillin sensitive
Surgery
What are the Red flag symptoms of loss of vision?
Pain Red eye Rapid onset Focal neurology Diabetic Trauma Amaurosis fugax (painless temporary loss of vision)
