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Conjunctiva anatomy and physiology
- 1. CONJUNCTIVA: ANATOMY , PHYSIOLOGY, SYMPTOMATOLOGYAND CLASSIFICATION Pranay Shinde DNB Resident Deen Dayal Upadhyay Hospital,New Delhi
- 2. ANATOMY It is themucous membrane covering the under surface of the lids and anterior part of the eyeball upto the cornea.
- 3. Parts of conjunctiva •Palpebral; covering the lids—firmly adherent. • Forniceal; covering the fornices—loose—thrown into folds. • Bulbar; covering the eyeball—loosely attached except at limbus.
- 5. Palpebral conjunctiva • Subtarsalsulcus 2mm from posterior edge of the lid margin. • Richly vascular. • Extremely thin. • Strongly bound to the tarsal plate.
- 6. Palpebral conjunctiva issubdivided into three parts: 1)Marginal 2)Tarsal 3)Orbital
- 7. Conjunctival fornices • Transitionalregion between palpebral and bulbar conjunctivae. • Superior fornix 10 mm from limbus. • Inferior fornix 8 mm from limbus. • Lateral fornix 14mm from limbus. • Medially absent. • Ducts of lacrimal glands open into lateral part of superior fornix.
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- 10. Bulbar conjunctiva • Liesin contact with eyeball. • Thin, translucent and loosely attached by connective tissue to sclera and fascia bulbi. • A 3 mm ridge of bulbar conjunctiva around the cornea is called limbal conjunctiva.
- 11. Structure of conjunctiva •Histologically conjunctiva consists of 3 layers: • 1) epithelium • 2)adenoid layer • 3)fibrous layer
- 12. Epithelium • Marginal conjunctiva:5 layered non keratinised stratified squamous • Tarsal conjunctiva: 2 layered in upper lid & • 3-4 layered in lower lid • Fornix & bulbar: 3 layered • Limbal conjunctiva: 8-10 layered
- 13. Conjunctival Glands • Thereare two types of conjunctival glands: • 1)Mucin secreatory glands • & • 2)Accessory lacrimal glands
- 14. Nerve supply -Sensory • Bulbar conjunctiva – long ciliary nerves – nasociliary N. – Ophthalmic division of trigeminal N. • Superior palpebral and forniceal conjunctiva – frontal and lacrimal branches of Ophthalmic division of trigeminal N. • Inferior palpebral and forniceal conjunctiva – laterally from lacrimal branches of Ophthalmic division of trigeminal N. and medially infraorbital N. – Maxillary division of trigeminal N. Sympathetic; • Superior cervical sympathetics to blood vessels.
- 15. Blood Supply • Palpebralconjunctiva & fornices are supplied by branches from the marginal and peripheral arcades of the eyelids • while, • Bulbar conjunctiva is supplied by posterior & anterior conjunctival arteries
- 16. Venous drainage: The veinsfrom conjunctiva drain into the venous plexus of eyelids which in turn drain into the superior and inferior ophthalmic veins. A cicumcorneal zone of limbus drain into the anterior cilliary veins
- 18. Lymphatic drainage • Lymphvessels are arranged as a superficial and a deep plexus in sub mucosa. • Ultimately as in the lids to the pre auricular and sub-mandibular lymph glands.
- 19. PHYSIOLOGY • Smooth surface. •Secretes mucin and aqueous component of tear film. • Highly vascular: supplies nutrition to the peripheral cornea. • Aqueous veins drains from anterior chamber maintenance of IOP. • Lymphoid tissue helps in combating infections. • Basic secretion—reflex secretion.
- 20. Symptomatology Non-Specific; • Lacrimation. • Irritation. •Stinging. • Burning. • Photophobia. • Redness. Specific; • Pain and FB sensation in corneal involvement. • Itching in allergic, blephritis and dry eyes.
- 21. SIGNS • Type ofdischarge. • Type of conjunctival reaction. • Presence of membrane/ pseudomembrane. • Lymphadenopathy.
- 22. DISCHARGE Exudate plus debrisplus mucus plus tears. • Serous; watery exudate in acute viral and acute allergic conjunctivitis. • Mucoid; mucus discharge in VKC and KCS (dry eyes). • Purulent; puss in severe acute bacterial conjunctivitis. • Mucopurulent; puss plus mucus in mild bacterial conjunctivitis and Chlamydial conjunctivitis.
- 23. TYPE OF CONJUNCTIVAL REACTION •Hyperaemia: (Conjunctival injection) Bacterial. • Sub-conjunctival Haemorrhage: Viral. • Bleeding: • Chemosis: (Oedema) • Scarring: Trachoma, cicatricial pemphigoid, atopic conjunctivitis and prolong use of topical drops. • Follicular reaction. • Papillary reaction.
- 24. Follicular reaction • Subepithelial foci of hyperplastic of lymphoid tissue with in stroma. • More prominent in fornices. • Multiple, discrete, slightly elevated, lesions encircled by a tiny blood vessel—small grains of rice. • Size from 0.5 to 5 mm. 1. Viral. 2. Chlamydial. 3. Parinaud oculoglandular syndrome. 4. Hypersensitivity to topical medications.
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- 26. Papillary reaction • Hyperplasticconjunctival epithelium. • Can develop in palpebral conjunctiva (firmly attached) and limbus. • Papilla may mask follicles. • Giant papilla (confluence) • Non-specific; (less diagnostic) 1. Chronic blephritis. 2. Allergic conjunctivitis. 3. Bacterial conjunctivitis. 4. Contact lens wears. 5. Superior limbic keratoconjunctivitis. 6. Floppy eyelid syndrome.
- 27. Pseudomembrane • Outside epithelium. •Coagulated exudate adherent to the inflammed epithelium. • Can be easily pealed off. • Causes; 1. Severe adenoviral infection. 2. Ligneous conjunctivitis. 3. Gonococcal conjunctivitis. 4. Stevens-Johnson syndrome.
- 28. Membrane • Includes epithelium. •Infiltrate the superficial layers of conjunctival epithelium. • Epithelium is injured if removal attempted. • Causes; 1. Diphtheria. 2. Beta-hemolytic steptococci.
- 29. Lymphadenopathy • Pre auricularand sub mandibular. 1. Viral infection. 2. Chlamydial infection. 3. Severe bacterial infections. (Gonococcal) 4. Parinaud oculoglandular syndrome.
- 30. Laboratory Investigations Indications: • Severpurulent conjunctivitis. • Follicular conjunctivitis: viral vs chlamydial. • Conjunctival inflammation. • Neonatal conjunctivitis.
- 31. Laboratory Investigations— cont… • Cultures. •Cytological investigations. • Inoculation. • Detection of viral and chlamydial antigens. • Impression cytology for ocular surface neoplasia, dry eyes, ocular cicatricial pemphigoid, limbal stem cells failure, infection. • Polymerase chain reaction: small quantity of DNA for adenovirus, herpes simplex, chlamydia trachomatis.
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