Conjunctival diseases: Conjunctivitis. Etiology. Classification. Diagnostics. Treatment. Dystrophic diseases of the conjunctiva.
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Conjunctival Diseases: Conjunctivitis & Dystrophic Conditions
ANATOMY OF THE CONJUNCTIVA
The conjunctiva is a transparent mucous membrane lining the inner surface of the eyelids and the anterior surface of the globe, terminating at the corneoscleral limbus. It is divided into:
- Palpebral conjunctiva — firmly attached to the posterior tarsal plates; tarsal blood vessels run vertically
- Fornical conjunctiva — loose and redundant
- Bulbar conjunctiva — covers the anterior sclera; continuous with the corneal epithelium at the limbus
Histology: Non-keratinizing stratified squamous epithelium (~5 cell layers deep) with mucus-secreting goblet cells (most dense inferonasally and in the fornices). The stroma contains the accessory lacrimal glands of Krause and Wolfring. Lymphatic drainage goes to the preauricular and submandibular nodes.
CONJUNCTIVITIS
Definition & General Features
Conjunctivitis is inflammation of the conjunctiva, presenting with:
- Redness, grittiness/foreign body sensation, discharge, photophobia, blurred vision
Classification
| Type | Subtype | Key Pathogens/Causes |
|---|---|---|
| Infectious | Bacterial | S. pneumoniae, S. aureus, H. influenzae, M. catarrhalis, N. gonorrhoeae |
| Viral | Adenovirus (most common), HSV, EBV, molluscum | |
| Chlamydial | C. trachomatis (trachoma; adult inclusion) | |
| Neonatal | N. gonorrhoeae, C. trachomatis, HSV, staphylococci | |
| Allergic | Seasonal/perennial | Pollen, dust mites |
| Vernal (VKC) | Atopic; young males, warm climates | |
| Atopic (AKC) | Atopic dermatitis | |
| Giant papillary (GPC) | Contact lens wear | |
| Other | Chemical/toxic | Topical medications, irritants |
| Autoimmune | OCP, SJS, GvHD |
BACTERIAL CONJUNCTIVITIS
Acute Bacterial Conjunctivitis
Etiology: S. pneumoniae, S. aureus, H. influenzae, M. catarrhalis (most common); N. gonorrhoeae causes severe hyperacute disease and can perforate the intact cornea.
Diagnosis:
- Symptoms: Acute onset redness, grittiness, burning, mucopurulent discharge; lids stuck together on waking; usually bilateral (one eye 1–2 days before the other)
- Signs: Conjunctival injection, mucopurulent discharge → hyperacute purulent discharge raises suspicion for gonococcal/meningococcal infection; superficial corneal punctate erosions
- Lymphadenopathy is usually absent (except in severe gonococcal/meningococcal infection)
- Investigations (not routine, only in severe/atypical cases):
- Conjunctival swabs + Gram stain (Gram-negative intracellular diplococci = N. gonorrhoeae)
- Culture on enriched/chocolate agar or Thayer-Martin medium for gonococci
- PCR for chlamydial/viral co-infection if treatment fails
Treatment:
- Self-limiting in most cases (resolves in 1–2 weeks without treatment)
- Topical broad-spectrum antibiotics (e.g., chloramphenicol 0.5% drops 4×/day or ciprofloxacin 0.3% 4×/day for 5–7 days) reduce duration and transmission
- Gonococcal conjunctivitis: Systemic ceftriaxone (single IM/IV dose) + topical irrigation; treat for concurrent chlamydia
- Chlamydial inclusion conjunctivitis (adult): Oral azithromycin single 1 g dose or doxycycline 100 mg twice daily for 7 days; treat sexual partners
Bacterial conjunctivitis is significantly less common than viral. MRSA prevalence has increased over the past decade. — Rosen's Emergency Medicine
VIRAL CONJUNCTIVITIS
Etiology: Adenovirus is by far the most common (highly contagious, spread by fomites). Others: HSV, EBV, enterovirus 70.
Clinical features:
- Often preceded by URI with sequential bilateral involvement
- Watery, non-purulent discharge (though purulence does NOT exclude viral cause)
- Follicular conjunctivitis — subepithelial germinal centres, avascular lymphoid aggregates
- Preauricular lymphadenopathy — classic for viral/chlamydial etiology
- Lasts 1–3 weeks
Epidemic keratoconjunctivitis (EKC): More virulent adenoviral infection; highly contagious; pseudomembranes; subepithelial corneal infiltrates (nummular keratitis); foreign body sensation; may cause long-term visual impairment.
Diagnosis:
- Clinical; follicles + preauricular node points toward viral origin
- Slit-lamp fluorescein staining for corneal involvement
- Adenovirus rapid antigen test or viral PCR for confirmation when needed
Treatment:
- Supportive: Cool compresses, lubricants, topical antihistamines for discomfort
- No effective topical antivirals for adenovirus
- HSV conjunctivitis: Topical aciclovir 3% 5×/day or oral aciclovir; important to recognize to avoid inadvertent topical steroids
- Topical steroids only in severe membrane/pseudomembrane formation or significant keratitis (under ophthalmology supervision)
CHLAMYDIAL CONJUNCTIVITIS
Trachoma
Etiology: Chlamydia trachomatis serovars A, B, Ba, C — world's leading cause of preventable irreversible blindness. Associated with poverty, overcrowding, poor hygiene, and fly transmission.
Pathogenesis: Recurrent reinfection → chronic cell-mediated (Type IV) hypersensitivity → conjunctival scarring → entropion/trichiasis → corneal abrasion → blindness.
WHO Grading:
| Grade | Findings |
|---|---|
| TF (Trachomatous Inflammation—Follicular) | ≥5 follicles on upper tarsal conjunctiva |
| TI (Trachomatous Inflammation—Intense) | Marked papillary response obscuring >50% of deep vessels |
| TS (Trachomatous Scarring) | Scarring of tarsal conjunctiva (Arlt's line) |
| TT (Trichiasis) | ≥1 eyelash rubbing on the eyeball |
| CO (Corneal Opacity) | Affecting the pupillary area |
Active trachoma: Mixed follicular/papillary conjunctivitis with mucopurulent discharge; limbal follicles (Herbert pits on healing); superior pannus.
Treatment (WHO SAFE strategy):
- Surgery for trichiasis (bilamellar tarsal rotation)
- Antibiotics: Azithromycin single dose (20 mg/kg up to 1 g) — treatment of choice; or doxycycline 100 mg twice daily ×10 days; topical tetracycline ointment less effective
- Facial cleanliness
- Environmental improvement (water, sanitation, fly control)
NEONATAL CONJUNCTIVITIS (Ophthalmia Neonatorum)
Defined as conjunctivitis in the first month of life; occurs in up to 10% of neonates. Requires specific workup due to risk of serious ocular and systemic complications.
Causes and timing of onset:
| Cause | Onset |
|---|---|
| Chemical (prophylaxis) | First few days |
| N. gonorrhoeae | First week (hyperacute purulent discharge; risk of corneal perforation) |
| Other bacteria (S. aureus, streptococci) | End of first week |
| HSV-2 | 1–2 weeks |
| C. trachomatis | 1–3 weeks (most common cause of moderate-severe cases) |
Diagnosis: Conjunctival swabs for Gram stain, culture, Giemsa stain for chlamydial inclusions, PCR for HSV and chlamydia; neonatal systemic assessment for pneumonitis/rhinitis (chlamydia), vesicles/encephalitis (HSV), disseminated infection (gonococcal).
Treatment:
- Gonococcal: IV/IM ceftriaxone + ocular irrigation
- Chlamydial: Oral erythromycin for 14 days (topical ineffective)
- HSV: IV aciclovir (risk of CNS involvement)
- Prophylaxis: 2.5% povidone-iodine or 0.5% erythromycin ointment instilled at birth
ALLERGIC CONJUNCTIVITIS
Seasonal / Perennial Allergic Conjunctivitis (SAC/PAC)
Type I IgE-mediated hypersensitivity to environmental allergens (pollen, dust, animal dander).
Features: Bilateral itching, redness, watery discharge, chemosis (glassy appearance in severe cases), associated rhinitis/asthma. Seasonal (spring/summer) or year-round.
Treatment:
- Allergen avoidance, cold compresses
- Topical antihistamines/mast cell stabilizers (olopatadine, ketotifen, azelastine) — first-line
- Topical NSAIDs (ketorolac)
- Short course topical steroids for severe cases
- Oral antihistamines for systemic symptoms
Vernal Keratoconjunctivitis (VKC)
Severe, recurrent, bilateral, affecting young males in warm climates; associated with atopy.
Signs:
- Tarsal form: Giant papillae ("cobblestone") on superior tarsal plate
- Limbal form: Limbal Trantas dots (eosinophilic accumulations at limbus)
- Shield ulcer of cornea (central anterior stromal plaque) in severe cases
- Ropy mucous discharge
Treatment: Topical mast cell stabilizers (sodium cromoglicate, nedocromil); topical ciclosporin; supratarsal steroid injections; topical steroids with caution (steroid glaucoma/cataract risk).
Atopic Keratoconjunctivitis (AKC)
Associated with severe atopic dermatitis. Can lead to corneal vascularization, subepithelial fibrosis, cataract (anterior or posterior subcapsular), keratoconus.
Giant Papillary Conjunctivitis (GPC)
Mechanically induced; associated with contact lens wear (allergy to sterilizing solutions/lens protein). Giant papillae under upper lid. Management: preservative-free solutions, daily-wear disposables, or lens holiday.
DIAGNOSTICS (General Approach)
| Finding | Implication |
|---|---|
| Mucopurulent discharge, bilateral morning crusting | Bacterial |
| Watery discharge + preauricular node + follicles | Viral |
| Itch, chemosis, bilateral, seasonal | Allergic |
| Intense purulent (hyperacute) discharge | Gonococcal / meningococcal |
| Cobblestone papillae, Trantas dots | Vernal |
| Tarsal conjunctival follicles + superior pannus | Trachoma |
| Corneal staining fluorescein | Keratoconjunctivitis, ulcer |
Key investigations:
- Slit-lamp examination (mandatory; identifies follicles, papillae, membranes, corneal involvement)
- Conjunctival swabs: Gram stain, culture (bacterial), Giemsa stain (chlamydial inclusions)
- PCR: C. trachomatis, HSV, adenovirus
- Rapid antigen tests (adenovirus)
- Impression cytology (keratinization, goblet cell loss)
- Biopsy for atypical/neoplastic lesions
DYSTROPHIC / DEGENERATIVE DISEASES OF THE CONJUNCTIVA
1. Pinguecula
Definition: A yellow-white, flat or slightly raised conjunctival lesion in the interpalpebral fissure adjacent to but NOT crossing the limbus. Does not involve the cornea.
Pathology: Elastotic degeneration of subepithelial connective tissue with fibrovascular proliferation; UV light and chronic irritation are the primary triggers.
Clinical: Usually bilateral, nasal > temporal; asymptomatic or mild irritation/redness. A "delle" (drying-related thinning of adjacent cornea) may form.
Treatment:
- UV-protective eyewear, lubricants (preservative-free artificial tears q4–8h)
- Topical NSAIDs or mild topical steroids (e.g., fluorometholone 0.1%, loteprednol 0.2%–0.5%) for acute inflammation
- Surgical excision rarely needed (cosmesis, persistent inflammation)
2. Pterygium
Definition: A chronic inflammatory fibrovascular hypertrophy of conjunctiva encroaching onto the cornea — characteristically triangular/wing-shaped, usually nasal, growing toward (and potentially over) the visual axis.
Pathology: Identical to pinguecula; elastotic degeneration triggered by UV exposure and chronic irritation. More common in equatorial populations.
Signs:
- Wing-shaped fold of fibrovascular tissue from interpalpebral conjunctiva onto the cornea
- Stocker line — iron line in the cornea just beyond the leading edge
- No associated corneal thinning beneath the lesion
- May induce irregular astigmatism; threatens the visual axis with advanced growth
Differential diagnosis: Pseudopterygium (adherent to cornea at site of prior trauma/cicatrization; probe can be passed underneath a true pterygium but not a pseudopterygium), CIN/squamous carcinoma, pannus, limbal dermoid.
Treatment:
- Conservative: UV protection, lubricants, topical NSAIDs/mild steroids for inflamed lesions
- Surgical excision indicated when:
- Threatening visual axis
- Significant induced astigmatism
- Excessive irritation unresponsive to medical therapy
- Contact lens intolerance or cosmetic concerns
- Pre-cataract/refractive surgery
- Recurrence prevention: Conjunctival autograft or amniotic membrane graft significantly reduces recurrence. Intraoperative mitomycin C (antimetabolite) is used for recurrent pterygium (risk of corneoscleral thinning).
3. Conjunctivochalasis
Redundant, non-inflamed bulbar conjunctiva, typically at the inferior limbus. Can cause epiphora, foreign body sensation, and instability of the tear film. Treated with lubricants; surgery (conjunctival resection or cauterization) for symptomatic cases.
4. Xerophthalmia (Vitamin A deficiency)
Conjunctival findings:
- Xerosis: Dryness of the interpalpebral conjunctiva, loss of goblet cells, squamous metaplasia and keratinization
- Bitot spots: Triangular foamy patches of keratinized epithelium in the interpalpebral zone; caused by Corynebacterium xerosis
WHO Grading of Xerophthalmia:
| Grade | Features |
|---|---|
| XN | Night blindness |
| X1A | Conjunctival xerosis |
| X1B | + Bitot spots |
| X2 | Corneal xerosis |
| X3A/B | Corneal ulceration </>⅓ |
| XS | Corneal scar |
| XF | Xerophthalmic fundus |
Treatment: Vitamin A supplementation (200,000 IU oral or 100,000 IU IM); keratomalacia is a medical emergency; intense lubrication, topical retinoic acid.
5. Concretions
Tiny white-yellow deposits in the palpebral conjunctiva (degenerated epithelial cells and inflammatory debris within the crypts of Henle). Rarely symptomatic; can be removed if causing foreign body sensation.
6. Subconjunctival Hemorrhage
Spontaneous hemorrhage between the conjunctiva and sclera. Causes: Valsalva, hypertension, coagulopathy, trauma, or idiopathic. Bright red, sharply demarcated. Self-resolves within 1–2 weeks; no treatment needed. Recurrent cases warrant blood pressure and coagulation assessment.
Key Differential Features Summary
| Feature | Bacterial | Viral | Allergic |
|---|---|---|---|
| Discharge | Mucopurulent | Watery/mucoid | Watery/ropy (VKC) |
| Itch | Absent | Absent | Present (hallmark) |
| Preauricular node | Rare (severe only) | Common | Absent |
| Follicles | Absent | Present | Absent (papillae in VKC/GPC) |
| Bilateral | Usually | Sequential | Yes |
| Duration | 7–10 days | 1–3 weeks | Chronic/recurrent |
Sources:
- Kanski's Clinical Ophthalmology: A Systematic Approach, 10th ed. (Chapters 6, 7)
- Rosen's Emergency Medicine: Concepts and Clinical Practice (Chapter 57)
- The Wills Eye Manual, Office and Emergency Room Diagnosis and Treatment, 8th ed. (Section 4.9)
- Bailey and Love's Short Practice of Surgery, 28th ed. (Chapter 49)
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