Conjunctivitis Flashcards
What is conjunctivitis?
- inflammation of the lining of the eyelids and eyeball
- common, not usually serious
- can be uni or bilateral
Describe the signs and symptoms of conjunctivitis
-
discharge
- watery -> viral
- ropy, mucoid -> allergic
- purulent -> bacterial
- itching
- eyelids stuck together in morning
- tender, pre-auricular lymphadenopathy
What are the risk factors for conjunctivitis?
- exposure to infected person
- infection in one eye
- env irritants
- allergen exposure
- camps, swimming pools, military bases
- asian or mediterranean young male
- atopic dermatitis
- contact lens use
- ocular prosthesis
- mechanical irritation
What are the non-infectious causes of conjunctivitis?
- allergic - most common, affect 15-40% of population
- other: toxic, autoimmune, neoplastic,
- contact lens wear may lead to a keratoconjunctivitis or giant cell papillary conjunctivitis
The conjunctiva contains non-keratinising, squamous epithelium and a thin, richly vascularised substantia propria. The conjunctiva also has accessory lacrimal glands and goblet cells.
What is the pathophysiology of allergic conjunctivitis?
- caused by type I immune response to an allergen
- allergen binds to a mast cell + cross-linking to IgE occurs
- leads to mast cell degranulation and inititation of an inflammatory cascade
- this results in release of histamine from mast cells as well as other mediators (tryptase, chymase, heparin, pgs, txa, lts)
- histamine and bradykinin immediately stimulate nociceptors
- results in itching, inc vasc perm, vasodilation, redness and conjunctival injection
What is the pathophysiology of infective conjunctivitis?
- occurs as a result of reduced host defences + external contamination
- infectious pathogens can invade from adjacent sites or by blood-borne path + replicate within conjunctival mucosal cells
- both bact + viral infections initiate a leukocyte or lymphocytic inflammatory cascade
- leading to attraction of red and white blood cells to area
- these WBCs reach the conjunctival surface + accumulate there by easily moving through the dilated + highly permeable capillaries
What are the most common bacterial pathogens in infective conjunctivitis?
- pneumococcus
- staph aureus
- moraxella catarrhalis
- haemophilus influenzae
Rarely, neisseria gonorrhoea cause a hyperacute purulent conjunctivitis; the organism is transmitted from genitalia to hands then to eyes. Chlamydia is a common cause of persistent conjuntivitis
What organisms cause viral conjunctivitis?
- adenovirus (~80%)
- herpes simplex
- epstein-barr
- varicella zoster
- molluscum contagiosum
- coxsackie
- enteroviruses
Adenoviral conjunctivitis usually causes epidemic keratoconjunctivitis, follicular conjunctivitis, and non-specific conjunctivitis.
Viral conjunctivitis is highly contagious and spreads by direct contact w/ ppl or contaminated surfaces exposed to secretions.
What are the 3 classifications of bacterial conjunctivitis?
- gonococcal (hyperacute) bacterial conjunctivitis
- non-gonococcal bacterial conjunctivitis
- chlamydial conjunctivitis
What are the 3 classifications of viral conjunctivitis?
- adenoviral conjunctivitis
- herpetic conjunctivitis
- other viruses
Hyperacute presentation over 24 to 48 hours with copious whitish-yellow discharge in a sexually active person is consistent with what type of conjunctivitis?
- neisseria gonorrhoeae
When and how do you investigate conjunctivitis?
- conjunctival cultures only needed if you suspect:
- gonococcal/chlamydial infections
- neonatal conjunctivitis
- recurrent disease not responding to therapy
What is the medical treatment for conjunctivitis?
Most cases are viral and only need symptomatic relief w/ artificial tears and topical anti-histamines. Topical anti-viral treatment doesn’t help, viral is self-resolving in 1-3 weeks.
- Bacterial is self-resolving in 5-7 days, antibiotics useful for symptomatic relief, especially useful in culture-proven conjunctivitis, start Abx immediately if sexual disease suspected, contact wearers or immunocompromised -> chloramphenicol 0.5% drops/4-6h used or chloramphenicol ointment qds (fusidic acid in preg women bd)
- Allergic conjunctivitis -> try antihistamine drops eg. emedastine or olopatadine (opatanol) and then topical mast cell stabilisers (sodium cromoglicate and nedocromil)
What advice should be given to patient on discharge, following conjunctivitis?
- inform about contagious nature
- bacterial -> may return to work/school after 24-48hrs of abx
- viral -> at least 1 week out of work/school
- advice regarding strict hand washing + not sharing towels or bedding
Following an uneventful pregnancy, a 19-year-old woman delivers a male child vaginally. At assessment one week later the child is noted to have purulent discharge and crusting of the eyelids.
What is the next step in the management of the child?
(source: passmed)
- Take urgent swabs of discharge for microbiological investigation
Although minor conjunctivitis with encrusting of the eyelids is common and often benign, a purulent discharge may indicate the presence of a serious infection (for example, with chlamydia or gonococcus).
In babies with a purulent eye discharge swab samples should be taken urgently for microbiological investigation, using methods that can detect chlamydia and gonococcus. While the guidance is to start systemic antibiotic treatment for possible gonococcal infection while awaiting the swab microbiology results, swabs must be taken first.
