Conjunctivitis Flashcards
Name the 2 layers of the conjunctiva.
Epithelium and stroma (adenoid and fibrous layers)
Define conjunctivitis (pink eye).
Conjunctivitis, or pink eye, is an inflammation of the transparent membrane that lines the eyelid and the eyeball (the conjunctiva).
What is conjunctivitis characterized by?
Dilation of the conjunctival vessels resulting in hyperemia and edema of the conjunctiva
How is conjunctivitis classified based on the following:
a) Etiology
b) Clinical course
c) Type of exudate
a) Infectious (bacterial, viral)
Non-infectious (allergic, irritant, secondary to systemic cause )
b) Acute (resolves <4weeks)
Chronic (persists >4 weeks)
c) Purulent
Mucopurulent
Membranous
Pseudomembranous
Catarrhal
Describe the pathophysiology of allergic conjunctivitis.
- Allergen comes in contact with the conjunctiva, and this causes a type 1 hypersensitivity reaction.
- There is activation of mast cells due to allergen crosslinking of surface IgE receptors.
- Degranulation occurs and there is release of histamines, cytokines and prostaglandins.
- These substances then induce vascular leakage causing cellular infiltration of eosinophils and neutrophils.
Give 5 clinical features of conjunctivitis.
- Acute onset of redness
- Grittiness
- Photophobia
- Burning
- Eyelid edema and erythema
- Discharge( may be watery, mucoid, mucopurulent or purulent)
- Itching (usually in allergic conjunctivitis)
Give risk factors for each of the following causes of conjunctivitis.
BACTERIAL
- Contact with contaminated fingers or oculogenital contact
- Compromised tear production/drainage
- Trauma
- Immunosuppressed status
VIRAL
Contact with:
- Contaminated finger
- Medical instruments
- Swimming pool water
- Personal items from an infected person
ALLERGIC
- History of non-ocular allergic conditions e.g. eczema
Name 3 organisms which cause bacterial conjunctivitis.
Staphylococcus epidermidis, Staphylococcus aureus, Streptococcus pneumoniae, Hemophilus influenzae, and Moraxella lacunata.
What does Neisseria gonorrhea cause in neonates?
Ophthalmia neonatorum
What causes chlamydia conjunctivitis?
Chlamydia trachomatis serotypes D-K
What causes trachoma?
Chlamydia trachomatis serotypes A, B, Ba and C
Which strategery was used in the elimination of trachoma?
Surgery
Antibiotics
Facial cleanliness
Environmental improvement
Name 2 viruses that can cause viral conjunctivitis.
Adenovirus, Molluscum contagiosum, Herpes simplex
What are the 2 distinct syndromes from adenoviral conjunctivitis?
Pharyngoconjunctival fever- aerosol transmission, usually post upper respiratory tract infection
Epidemic keratoconjunctivitis- transmission by contact (fingers, instruments), there is an 80% chance of developing keratitis
What do patients with molluscum contagiosum conjunctivitis present with?
Chronic history of umbilicated nodule at the lid margin
Name the 4 types of allergic conjunctivitis.
- Seasonal
- Vernal
- Atopic
- Acute
Give 5 differential diagnosis for conjunctivitis.
- Pre-septal Cellulitis
- Orbital Cellulitis
- Traumatic Eye
- Injuries
- Acute angle-closure glaucoma
- Keratitis
- Scleritis
- Sub-conjunctival hemorrhage
- Anterior uveitis
- Corneal ulcer
- Episcleritis
- Blepharitis
How is conjunctivitis diagnosed?
Usually clinical but the following can be done:
- Visual Acuity Test
- Fluorescein Stain
- Slit Lamp Examination
- Swab for Gram stain and Culture
What is the supportive therapy for conjunctivitis?
- Refrigerated artificial tears
- Cleaning discharge from eyes
- Compresses (warm/cold)
- Discontinuation of contact lens use if applicable
How is allergic conjunctivitis managed?
- Combined vasoconstrictor/antihistamine e.g. naphazoline/pheniramine
- Histamine H1 receptor antagonists e.g. azelastine
- Oral antihistamines e.g. cetirizine
- Corticosteroids
Give complications for each cause of conjunctivitis.
BACTERIAL
- Corneal ulcer (especially with aggressive organisms like Neisseria gonorrhoeae or
- Pseudomonas)
- Keratitis
- Vision loss (very rare)
- Conjunctival scarring
VIRAL
- Subepithelial corneal infiltrates
- Keratitis
- Secondary bacterial infection (if epithelial barrier is damaged)
- Symblepharon (rare)
ALLERGIC
- Keratitis (in severe cases)
- Conjunctival scarring (rare, chronic severe allergies)
