Ophthalmology Flashcards
What symptom distinguishes scleritis from episcleritis?
Pain
Treatment for infectious conjunctivitis?
Topical chloramphenicol (antibiotic)
Features of bacterial conjunctivitis vs viral conjunctivitis
Bacterial: purulent discharge, eyes stuck together in morning
Viral: serous discharge, recent URTI, preauricular lymph nodes
What is orbital cellulitis?
Orbital cellulitis is the result of an infection affecting the fat and muscles posterior to the orbital septum, within the orbit but not involving the globe.
It is usually caused by a spreading upper respiratory tract infection from the sinuses and carries a high mortality rate.
It is a medical emergency requiring hospital admission and urgent senior review.
What is periorbital cellulitis?
Periorbital cellulitis/ preseptal cellulitis is an infection of the soft tissues anterior to the orbital septum- this includes the eyelids, skin and subcutaneous tissue of the face, but not the contents of the orbit.
Risk factors for orbital cellulitis
-childhood
-previous sinus infection
-lack of Haemophilus influenzae type b (Hib) vaccination
-recent eyelid infection/insect bite on eyelid (peri-orbital cellulitis)
-ear or facial infection
Clinical features of orbital cellulitis
5 P’s :
Pain
Proptosis (exophthalmos)
Periocular oedema/swelling
Pupil involvement and visual changes- blurred vision, decreased visual acuity, diplopia….
Palsy (ophthalmoplegia)
What are the most common bacterial causes of orbital cellulitis?
Streptococcus, staphylococcus aureus, haemophilus influenzae B
Investigations for orbital cellulitis
Full blood count – WBC elevated, raised inflammatory markers.
Clinical examination involving complete ophthalmological assessment – Decreased vision, afferent pupillary defect, proptosis, dysmotility, oedema, erythema.
CT with contrast – Inflammation of the orbital tissues deep to the septum, sinusitis.
Blood culture and microbiological swab to determine the organism. Most common bacterial causes – Streptococcus, Staphylococcus aureus, Haemophilus influenzae B.
Management of orbital cellulitis
Admission to hospital for IV antibiotics
Pathophysiology of preseptal/periorbital cellulitis
Infection usually spreads to the structures surrounding the orbit from other nearby sites, most commonly from breaks in the skin or local infections such as sinusitis or other respiratory tract infections
What are the most frequent causative organisms of preseptal cellulitis?
Staph. aureus, staph. epidermidis, streptococci and anaerobic bacteria
clinical features of cellulitis
-red, swollen, painful eye of acute onset
-symptoms associated with fever
-erythema and oedema of the eyelids, which can spread onto the surrounding skin
-partial or complete ptosis of the eye due to swelling
investigations of preseptal cellulitis
Bloods - raised inflammatory markers
Swab of any discharge present
Contrast CT of the orbit may help to differentiate between preseptal and orbital cellulitis. It should be performed in all patients suspected to have orbital cellulitis
management of preseptal cellulitis
All cases should be referred to secondary care for assessment
Oral antibiotics are frequently sufficient - usually co-amoxiclav
Children may require admission for observation
What are the features of Horner’s syndrome?
Basics: Miosis, ptosis, enophthamos, andhidrosis
Clinical features:
Anisocoria: -miosis on affected side
-relative pupillary dilation lag in darkness (2-8 seconds)
Pitosis: - partial ptosis due to a weakness of Muller’s muscle
-involvement of levator palpebrae superioris may lead to more pronounced ptosis
-Ipsilateral loss of sweating (anhidrosis) over forehead, face and neck regions.
-Facial vasodilation due to loss of sympathetic tone
Heterochromia Iridum (in congenital cases):
-lighter iris colour in the affected eye
-due to a lack of melanin deposition during development
Enophthalmos (rare)
-slight posterior displacement of the eyeball within the orbit
-attributed to loss of sympathetic innervation to orbital smooth muscles
Describe Horner’s syndrome
Horner’s syndrome is a rare condition that affects the sympathetic nervous system.
AKA oculosympathetic paresis
Classic triad of ptosis, miosis and anhidrosis
It results from a lesion to the sympathetic pathway that supplies the head and neck, including the oculosympathetic fibers.
The cause of Horner’s syndrome varies with the site of the lesion.
What does anisocoria mean?
Difference in pupil sizes
How do central lesions in Horner’s syndrome present and what are the causes?
-Anhidrosis of the face, arm and trunk
-Stroke, syringomyelia (cyst in spinal cord), multiple sclerosis, tumour, encephalitis
How do pre-ganglionic lesions present in Horner’s syndrome and what are the causes?
Anhidrosis of the face
-Pancoast’s tumour, thyroidectomy, trauma, cervical rib
How do post-ganglionic lesions present in Horner’s syndrome and what are the causes
No anhidrosis
-Carotid artery dissection, carotid aneurysm, cavernous sinus thrombosis, cluster headache
