Overview of Conjunctivitis
Conjunctivitis (commonly called "pink eye") is inflammation of the conjunctiva -- the transparent mucous membrane lining the inner eyelids and anterior sclera. It is among the most common reasons patients seek ophthalmic care. The CPOA is often the first clinical contact for these patients, making it essential to differentiate between the major types and recognize features that require urgent physician evaluation.
Types of Conjunctivitis
| Type | Discharge | Laterality | Key Features |
|---|---|---|---|
| Bacterial | Mucopurulent (thick, yellow-green) | Often bilateral (can start unilateral) | Lids stuck together in morning; no preitaural node |
| Viral (adenovirus) | Watery, serous | Usually starts unilateral, becomes bilateral | Preauricular lymph node, follicles on lower palpebral conjunctiva |
| Allergic | Watery, mucoid (stringy) | Bilateral | Intense itching, papillae, chemosis; seasonal or perennial |
| Chlamydial | Mucopurulent, chronic | Bilateral | Follicles superior > inferior; sexually active adults; genital history |
Bacterial Conjunctivitis
Common organisms include Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae. In neonates, gonococcal (N. gonorrhoeae) or chlamydial conjunctivitis must be ruled out urgently. Bacterial conjunctivitis is typically self-limiting in 7-10 days, but topical antibiotics (trimethoprim/polymyxin, erythromycin, fluoroquinolones) reduce duration and communicability.
⚠️ Common Mistake: Hyperacute (profuse) purulent discharge with rapid onset, especially in sexually active patients, raises concern for Neisseria gonorrhoeae -- a true ocular emergency. Gonococcal conjunctivitis can penetrate the cornea and cause perforation within hours. Alert the physician immediately.
Viral Conjunctivitis
Adenovirus is by far the most common cause, causing epidemic keratoconjunctivitis (EKC) -- one of the most contagious of all eye infections. Features:
- Watery discharge, red eye, tearing
- Preauricular lymph node (often palpable)
- Follicular reaction on inferior palpebral conjunctiva
- Pseudomembranes may form in severe cases
- Subepithelial infiltrates (SEIs) may appear weeks later and can blur vision
There is no specific antiviral treatment for adenoviral conjunctivitis. Management is supportive: cold compresses, artificial tears, and strict infection control (handwashing, not sharing towels). EKC can remain contagious for 10-14 days.
💡 Clinical Tip: Adenoviral conjunctivitis is highly contagious. Instruments (tonometer tips, lenses) that contact the patient's eye must be properly disinfected. The CPOA plays a key role in preventing spread within the clinic by following infection control protocols carefully.
Allergic Conjunctivitis
Allergic conjunctivitis is an IgE-mediated hypersensitivity response to airborne allergens. The hallmark symptom is itching -- bilateral, often intense. Types include:
- Seasonal allergic conjunctivitis (SAC): pollen-driven; the most common
- Perennial allergic conjunctivitis (PAC): year-round triggers (dust mites, pet dander)
- Vernal keratoconjunctivitis (VKC): severe form in young males; giant papillae on the upper tarsal conjunctiva ("cobblestoning"); can cause corneal shields
- Giant papillary conjunctivitis (GPC): caused by contact lens wear or ocular prostheses; papillae on upper tarsal conjunctiva
Treatment: antihistamine/mast cell stabilizer eye drops (ketotifen, olopatadine), cold compresses, avoiding triggers. Topical steroids for severe cases (with caution -- risk of cataracts and IOP elevation).
Chlamydial Conjunctivitis
Inclusion conjunctivitis from Chlamydia trachomatis (serovars D-K) presents in sexually active adults as chronic mucopurulent conjunctivitis with superior palpebral follicles. It responds to systemic azithromycin or doxycycline (topical alone is insufficient). Partners should be treated. Trachoma (serovars A-C) is the leading infectious cause of blindness worldwide; it causes scarring of the upper tarsal conjunctiva (pannus) and trichiasis.
Other External Eye Conditions
Blepharitis
Blepharitis is chronic eyelid margin inflammation, commonly from seborrheic dermatitis or Meibomian gland dysfunction (posterior blepharitis). Patients complain of irritation, burning, and morning crusting. Treatment: warm compresses, lid scrubs, omega-3s, and sometimes topical or oral antibiotics.
Pinguecula and Pterygium
A pinguecula is a yellowish conjunctival deposit on the nasal or temporal bulbar conjunctiva from UV/wind exposure -- does not invade the cornea. A pterygium is a fleshy, vascularized growth that extends onto the cornea from the limbus; it can induce astigmatism and obstruct vision. Surgical excision is needed for symptomatic pterygium.
Key Takeaways
- Discharge type helps classify conjunctivitis: mucopurulent (bacterial), watery (viral), stringy/mucoid (allergic)
- Itching is the hallmark of allergic conjunctivitis; preauricular node suggests viral
- Adenoviral conjunctivitis is highly contagious; strict infection control is essential
- Hyperacute purulent discharge may indicate gonococcal conjunctivitis -- a corneal emergency
- Chlamydial conjunctivitis requires systemic treatment, not topical antibiotics alone
- Pterygium invades the cornea; pinguecula does not