Eyes: Conjunctivitis, Orbital & Periorbital Cellulitis Flashcards
What is conjunctivitis?
Inflammation of the conjunctiva (thin membrane that covers the sclera and lines the inner surface of the eye).
Conjunctivitis may be bacterial, viral or allergic.
What are the 4 most common bacterial causative organisms?
1) Staph. aureus
2) Strep. pneumoniae
3) H. influenzae
4) Moraxella catarrhalis
What are the 4 most common viral causes of conjunctivitis?
1) Adenovirus (most common)
2) HSV
3) VZV
4) Enterovirus
What is the most common virus causing infective conjuctivitis?
Adenovirus
Features of bacterial vs viral conjunctivitis?
Bacterial:
- purulent discharge
- eyes may be ‘stuck together’ in morning
Viral:
- serous discharge
- recent URTI e.g. dry cough, sore throat
- preauricular lymph nodes
Are bacterial & viral conjunctivitis contagious?
yes - both are
Onset of symptoms in conjunctivitis?
Acute onset of symptoms, typically unilateral but may become bilateral within 24-48 hours.
What may be present in history in conjunctivitis?
- Recent exposure to an infected individual, swimming in contaminated water, or contact lens use.
- Presence of comorbidities e.g. URTI or atopy.
Clinical symptoms of conjunctivitis?
-Red, bloodshot eye
- Ocular discomfort, itching, burning sensation.
- Foreign body sensation or grittiness in the affected eye(s).
- Photophobia may be present in cases of viral conjunctivitis.
- Discharge: watery in viral, purulent in bacterial
What symptoms does conjunctivitis NOT cause?
Does NOT cause pain, photophobia or reduced visual acuity.
Discharge covering the eye may cause blurry vision, but this should return to normal when the discharge is cleared.
Potential clinical signs in conjunctivitis?
- Conjunctival injection and chemosis.
- Eyelid swelling and erythema.
- Palpable preauricular lymphadenopathy (viral)
- Subconjunctival haemorrhage may be present in cases of adenoviral conjunctivitis
what are some causes of an acute PAINFUL red eye? (7)
1) Acute angle-closure glaucoma
2) Anterior uveitis
3) Scleritis
4) Corneal abrasions or ulceration
5) Keratitis
6) Foreign body
7) Traumatic or chemical injury
Note - Conditions that require emergency same-day referral to ophthalmology tend to cause pain or reduced visual acuity.
what are some causes of an acute PAINLESS red eye? (3)
1) Conjunctivitis
2) Episcleritis
3) Subconjunctival haemorrhage
Typical management of infective conjunctivitis?
Normally a self-limiting condition that usually settles without treatment within 1-2 weeks.
Hygiene measures to reduce spreading e.g. avoiding towel sharing and close contact.
Clean eyes with cooled boiled water and cotton wool can help clear the discharge.
What are 2 pharmacological options for bacterial conjunctivitis if necessary?
1) Chloramphenicol (eye drops)
2) Fusidic acid (eye drops)
What medical management is indicated for conjunctivitis in pregnant women?
Fusidic acid
Indications for chloramphenicol? (2)
1) Superficial bacterial eye infections
2) Bacterial infection in otitis externa
Key contraindications of chloramphenicol?
Acute porphyrias
Pregnacy & breastfeeding
Is chloramphenicol safe in pregnancy & breast feeding?
No
What is risk of using Chloramphenicol in pregnancy?
‘Grey baby’ syndrome
What age children with conjunctivitis need urgent ophthalmology assessment?
Neonates <1 month old
Why do neonates with conjunctivitis need urgent ophthalmology assessment?
Neonatal conjunctivitis may be caused by gonococcal infection, which can cause serious complications (e.g., permanent vision loss).
Is school exclusion necessary in infective conjunctivitis?
No
What is allergic conjunctivitis?
An ocular inflammatory condition triggered by an immune response to various environmental allergens e.g. pollen, animal dander, and dust mites.
What type of reaction is involved in allergic conjunctivitis?
Type 1 hypersensitivity
Pathophysiology of allergic conjunctivitis?
The initial exposure to an allergen leads to sensitization of mast cells, which, upon re-exposure, release inflammatory mediators, including histamine, prostaglandins, and leukotrienes.
These mediators cause vasodilation, increased vascular permeability, and recruitment of eosinophils, resulting in the clinical manifestations of allergic conjunctivitis.
Clinical features of allergic conjunctivitis?
- Bilateral ocular itching and redness
- Watery or stringy, mucoid discharge
- Conjunctival chemosis and hyperemia
- Eyelid oedema and erythema
- Tearing and photophobia
Management of allergic conjunctivitis?
1) Allergen avoidance
2) Basic eye care e.g. avoid rubbing eyes as this may cause mast cell degranulation, cool compresses
3) Pharmacotherapy:
- topical antihistamines e.g. olopatadine, ketotifen
- topical mast cell stabilisers e.g. sodium cromoglicate, nedocromil
- topical corticsteroids
how do topical mast cell stabilisers work in allergic conjunctivitis?
Preventing mast cells from releasing histamine.
These require several weeks of use before they show any benefit.
Give 2 examples of topical antihistamines used in allergic conjunctivitis
1) Olopatadine
2) Ketotifen
Give 2 examples of topical cell stabilisers used in allergic conjunctivitis
1) Sodium cromoglicate
2) Nedocromil
What is periorbital/preseptal cellulitis?
Infection of the soft tissues ANTERIOR to the orbital septum –> eyelids, skin & subcutaneous tissue of the face (but not the contents of the orbit).
What is a key differential for periorbital cellulitis?
Orbital cellulitis (medical emergency)
Where does infection in preseptal cellulitis usually spread from?
From nearby sites e.g. breaks in the skin, local infections (e.g. sinusitis), other RTIs.
What are the 2 most common bacteria implicated in periorbital cellulitis?
1) Staph. aureus
2) Staph. epidermis
Clinical features of periorbital cellulitis?
- Red, swollen, painful eye of ACUTE onset
- Fever
- Partial or complete ptosis of the eye due to swelling
What investigation can help distinguish orbital & periorbital cellulitis?
Contrast CT
Are there orbital signs in periorbital cellulitis?
E.g. pain on movement of the eye, restriction of eye movements, proptosis, visual disturbance, chemosis, RAPD.
NO –> this indicates orbital cellulitis
Does pain & restriction of movement of eye indicate orbital or periorbital cellulitis?
orbital
Investigations in periorbital cellulitis?
1) Bloods: raised inflammatory markers
2) Swab of any discharge present
3) Contrast CT of the orbit –> differentiate between preseptal and orbital cellulitis
What investigation should be performed in ALL patients suspected to have orbital cellulitis?
Contrast CT of the orbit
Typical management of preseptal cellulitis?
Systemic Abx (oral or IV) e.g. co-amoxiclav
Note - can develop into orbital cellulitis, so vulnerable patients (e.g., children) or severe cases may require admission for monitoring.
What is orbital cellulitis?
Infection involving the fat and muscles POSTERIOR to the orbital septum.
Medical emergency –> hospital admission and urgent senior review
What is orbital cellulitis usually caused by?
Spreading URTI from the sinuses
Risk factors for orbital cellulitis?
1) Childhood
2) Previous sinus infection
3) Lack of Haemophilus influenzae type b (Hib) vaccination
4) Recent eyelid infection/ insect bite on eyelid (Peri-orbital cellulitis)
5) Ear or facial infection
A lack of which vaccine can predispose to orbital cellulitis?
Haemophilus influenzae type b (Hib)
Clinical features of orbital cellulitis? (5 P’s)
1) Pain
2) Proptosis
3) Periocular swelling (oedema): swollen eyelids, chemosis, erythema
4) Pupil involvement and visual changes
5) Palsy (opthalmoplegia)
Additional features: fever, malaise, 1ary infection e.g. sinusitis
Describe pain in orbital cellulitis
- throbbing or deep ache
- intensifies with eye movements
- can radiate to the forehead, cheek, or teeth
What causes proptosis in orbital cellultiis?
Inflammation and oedema of the orbital contents, or in severe cases, formation of an abscess.
This causes forward displacement or protrusion of the eyeball.
What is chemosis?
Swelling of the conjunctiva
What visual changes can orbital cellulitis cause?
- blurred vision
- decreased visual acuity
- diplopia
- loss of vision (severe)
- RAPD
what does a RAPD indicate in orbtial cellulitis?
Optic nerve involvement –> risk of permanent vision loss
What causes palsy/opthalmoplegia in orbital cellulitis?
Inflammation and swelling in the orbit can cause restriction or paralysis of the extraocular muscles, leading to impaired eye movements (ophthalmoplegia)
Investigations in orbital cellulitis?
1) FBC: raised WCC
2) Inflammatory markers: raised
3) CT with contrast
4) Blood culture & swab
What can CT with contrast show in orbital cellulitis?
Inflammation of the orbital tissues deep to the septum, sinusitis.
What are the 3 most common organisms implicated in orbital cellulitis?
1) Streptococcus
2) Staph. aureus
3) H. influenzae B
management of orbital cellulitis?
Admit for IV Abx
