Conjunctivitis ki types and etiological classification batao subject ophthalmology MBBS level
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Ab main ek complete, well-structured MBBS-level answer compile karta hoon Kanski's Clinical Ophthalmology ke content ke basis par.
Conjunctivitis - Types & Etiological Classification
(Kanski's Clinical Ophthalmology, 10th Edition - Ophthalmology)
Definition
Conjunctivitis = Conjunctiva ki inflammation. Yeh sabse common external ocular disease hai. Red eye ke majority cases conjunctivitis se hote hain.
CLASSIFICATION
A. Duration ke basis par
| Type | Duration |
|---|---|
| Acute | < 4 weeks |
| Subacute | 4 weeks |
| Chronic | > 4 weeks |
B. Etiological Classification (Main Classification)
1. BACTERIAL CONJUNCTIVITIS
(i) Acute Bacterial Conjunctivitis
Common organisms:
- Staphylococcus aureus
- Streptococcus pneumoniae
- Haemophilus influenzae
- Moraxella catarrhalis
Special organisms (severe cases):
- Neisseria gonorrhoeae - sexually transmitted, corneal epithelium ko directly invade karta hai (dangerous!)
- Neisseria meningitidis - rare, usually affects children
Signs:
- Bilateral redness (ek aankh 1-2 din pehle, doosri baad)
- Mucopurulent / purulent discharge
- Subconjunctival haemorrhage (severe cases)
- Eyelids subah chipke hue milte hain (stuck together on waking)
- Gonococcal - severely purulent "hyper-acute" presentation, corneal perforation ka risk
(ii) Chlamydial Conjunctivitis
a) Adult Inclusion Conjunctivitis (TRIC)
- Organism: Chlamydia trachomatis serotypes D-K
- Sexually active adults mein, genital infection se spread
- Chronic follicular conjunctivitis
- Typical: large follicles in lower fornix, mucopurulent discharge
- Preauricular lymphadenopathy
b) Trachoma (Granular Conjunctivitis)
- Organism: C. trachomatis serotypes A, B, Ba, C
- Sab se important cause of preventable blindness worldwide
- 5 stages (MacCallan classification) + WHO simplified grading (TF, TI, TS, TT, CO)
- Upper tarsal follicles, Herbert pits (superior limbus pe shallow depressions)
- Complications: Arlt line (scar), trichiasis, distichiasis, entropion, corneal opacity
- Dry eye (goblet cell destruction)
c) Ophthalmia Neonatorum (Neonatal Conjunctivitis)
- Conjunctival inflammation within first month of life
- Most common neonatal infection - up to 10% neonates
- Organisms acquired during vaginal delivery:
- Chlamydia trachomatis (most common cause in developed countries)
- N. gonorrhoeae (previously 25% childhood blindness)
- Herpes simplex virus
- Chemical (silver nitrate drops) - harmless, self-limiting
- Also: Staphylococcus, Escherichia coli, Pseudomonas
2. VIRAL CONJUNCTIVITIS
Key feature: Epidemic tendency, preauricular lymphadenopathy
(i) Adenoviral Conjunctivitis (Most Common Viral)
Two main clinical syndromes:
| Feature | Epidemic Keratoconjunctivitis (EKC) | Pharyngoconjunctival Fever (PCF) |
|---|---|---|
| Serotype | Ad 8, 19, 37 | Ad 3, 4, 7 |
| Keratitis | Subepithelial infiltrates common | Mild |
| Systemic | Minimal | Pharyngitis + fever + lymphadenopathy |
| Membrane | May form | Uncommon |
- Highly contagious, direct contact se spread
- Watery discharge, follicular reaction
- Pseudomembrane/membrane form ho sakta hai
(ii) Herpes Simplex Virus (HSV) Conjunctivitis
- Unilateral follicular conjunctivitis
- Periocular vesicles (eyelid skin pe)
- Dendrites on cornea (pathognomonic when present)
(iii) Herpes Zoster Ophthalmicus
- VZV reactivation
- Dermatomal distribution along V1
- Hutchinson's sign (nasociliary nerve involvement = tip of nose vesicles)
(iv) Molluscum Contagiosum
- Poxvirus
- Lid nodule se toxic follicular conjunctivitis
(v) Acute Hemorrhagic Conjunctivitis
- Enterovirus 70, Coxsackievirus A24
- Subconjunctival hemorrhages prominent
- Very rapid onset (12-24 hrs), epidemic
3. ALLERGIC CONJUNCTIVITIS
Hallmark symptom: ITCHING (khujli)
| Type | Features |
|---|---|
| Seasonal Allergic (Hay Fever) | Pollens, IgE-mediated Type I hypersensitivity, watery discharge, chemosis |
| Perennial Allergic | Dust mites, animal dander, year-round |
| Vernal Keratoconjunctivitis (VKC) | Children/young males, tropical countries, GIANT papillae (cobblestone) on upper tarsal, shield ulcer, Trantas dots at limbus |
| Atopic Keratoconjunctivitis (AKC) | Adults, associated with atopic dermatitis, lower tarsal papillae, corneal involvement, cataracts |
| Giant Papillary Conjunctivitis (GPC) | Contact lens wearers / ocular prosthesis, upper tarsal large papillae |
4. CHLAMYDIAL (already covered above under Bacterial/Chlamydial)
5. MISCELLANEOUS / OTHER CAUSES
(i) Conjunctivitis in Blistering Mucocutaneous Disease
- Stevens-Johnson Syndrome (SJS) / Toxic Epidermal Necrolysis (TEN)
- Ocular cicatricial pemphigoid (OCP)
- Symblepharon, dry eye, trichiasis - severe sequelae
(ii) Chemical / Toxic Conjunctivitis
- Topical drugs (preservatives), chlorinated swimming pools
- Chemical burns (acid/alkali)
(iii) Mechanical
- Foreign body, contact lens irritation
(iv) Fungal (Rare)
- Immunocompromised patients
DISCHARGE TYPE - Quick Summary (Clinically Important)
| Discharge | Etiology |
|---|---|
| Watery (serous) | Acute viral / acute allergic |
| Mucoid | Chronic allergic, dry eye |
| Mucopurulent | Chlamydial, mild bacterial |
| Purulent (moderate) | Acute bacterial |
| Severe purulent (hyperacute) | N. gonorrhoeae |
CONJUNCTIVAL REACTION TYPES (Morphological Classification)
| Reaction | Description | Etiology |
|---|---|---|
| Follicles | Lymphoid aggregates, avascular centers, more in lower fornix | Viral, chlamydial, toxic |
| Papillae | Vascularized, central vessel, fine/giant | Bacterial, allergic, GPC |
| Pseudomembrane | Coagulated exudate, can be peeled (epithelium intact) | Adenoviral, gonococcal, SJS |
| True Membrane | Embedded in epithelium, bleeding on removal | Severe adenoviral, diphtheria |
| Chemosis | Conjunctival oedema | Hypersensitivity, severe infection |
| Subconjunctival haemorrhage | Viral (petechial/small), bacterial (large/diffuse) | Viral/bacterial severe |
EXAM MNEMONICS
Trachoma causes of blindness: "Trachoma = Trichiasis + corneal Opacity" (SAFE strategy: Surgery, Antibiotics, Facial hygiene, Environment)
Ophthalmia neonatorum onset:
- Chemical (silver nitrate) - Day 1
- Gonococcal - Day 2-5
- Bacterial - Day 5-14
- Chlamydial - Day 5-14 (up to week 3)
- HSV - Day 6-14
Sources: Kanski's Clinical Ophthalmology - A Systematic Approach, 10th Edition; Wills Eye Manual, 8th Edition
Main point only
Conjunctivitis - Types & Etiological Classification
A. Duration-based
- Acute < 4 weeks
- Chronic > 4 weeks
B. Etiological Classification
1. BACTERIAL
- Common: S. aureus, S. pneumoniae, H. influenzae, Moraxella
- Severe/Hyperacute: N. gonorrhoeae (can invade intact cornea)
- Chlamydial:
- Adult Inclusion Conjunctivitis → serotypes D-K
- Trachoma → serotypes A, B, Ba, C (leading cause of preventable blindness)
- Ophthalmia Neonatorum → C. trachomatis (most common), N. gonorrhoeae, HSV, chemical
2. VIRAL
- Adenovirus → EKC (Ad 8,19,37) & Pharyngoconjunctival Fever (Ad 3,4,7)
- HSV → unilateral, follicular, dendrites
- HZV → Hutchinson's sign
- Enterovirus 70 / Coxsackie A24 → Acute Hemorrhagic Conjunctivitis
- Molluscum contagiosum → toxic follicular conjunctivitis
3. ALLERGIC
- Seasonal / Perennial → IgE-mediated, watery discharge
- VKC → giant cobblestone papillae, shield ulcer, Trantas dots
- AKC → adults, atopic dermatitis
- GPC → contact lens wearers
4. OTHERS
- Mucocutaneous disease → SJS, OCP
- Chemical/Toxic
- Fungal (rare, immunocompromised)
C. Discharge = Etiology Clue
| Discharge | Cause |
|---|---|
| Watery | Viral / acute allergic |
| Mucoid | Chronic allergic, dry eye |
| Mucopurulent | Chlamydial, mild bacterial |
| Purulent | Bacterial |
| Hyperacute purulent | N. gonorrhoeae |
D. Morphological Reaction
| Reaction | Etiology |
|---|---|
| Follicles | Viral, chlamydial |
| Papillae | Bacterial, allergic |
| Giant papillae | VKC, GPC |
| Pseudomembrane | Adenoviral, gonococcal |
| True membrane | Diphtheria, severe adenoviral |
Ophthalmia Neonatorum - Onset Order
Chemical (Day 1) → Gonococcal (Day 2-5) → Bacterial/Chlamydial/HSV (Day 5-14)
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