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message tuhin1986 about this ad The conjunctiva is a vital mucous membrane that plays a key role in ocular health. This guide provides a detailed reference for medical students, ophthalmologists, and healthcare professionals, covering the conjunctivas structure, function, and associated diseases. 1. Anatomical Parts and Layers The conjunctiva is a thin, transparent mucous membrane that lines the inner surface of the eyelids and covers the anterior sclera up to the limbus. Anatomical Divisions Palpebral Conjunctiva: Lines the inner surface of the eyelids. Forniceal Conjunctiva: Forms the conjunctival fornix, connecting the palpebral and bulbar parts. Bulbar Conjunctiva: Covers the anterior part of the sclera up to the corneal limbus. Histological Layers Epithelium: Non-keratinized stratified columnar epithelium with goblet cells. Goblet cells secrete mucin, contributing to the tear film. Substantia Propria (Stroma Loose connective tissue containing lymphocytes, plasma cells, and mast cells. Rich in blood vessels and lymphatics. 2. Nerve Supply The conjunctiva receives sensory innervation primarily from branches of the trigeminal nerve (cranial nerve V Sensory Innervation Upper Eyelid and Superior Conjunctiva: Supplied by the ophthalmic division (V1) via: Lacrimal nerve Frontal nerve Nasociliary nerve Lower Eyelid and Inferior Conjunctiva: Supplied by the maxillary division (V2) via: Infraorbital nerve Functional Role Provides tactile sensation. Triggers protective reflexes like blinking and tearing in response to irritation. 3. Blood Supply The conjunctiva has a rich vascular network that supports its metabolic needs and immune functions. Arterial Supply Palpebral Conjunctiva: Supplied by branches of the ophthalmic artery: Lateral and medial palpebral arteries Bulbar Conjunctiva: Supplied by: Anterior ciliary arteries Long posterior ciliary arteries Venous Drainage Drains into: Superior and inferior ophthalmic veins Facial vein via angular vein 4. Nutritional Supply Mechanisms The conjunctiva receives nutrients through: Direct vascular perfusion from its arterial supply. Diffusion from the tear film, especially for the avascular regions near the cornea. Lymphatic drainage helps maintain immune surveillance and fluid balance. 5. Abnormalities of the Conjunctiva Structural and functional abnormalities can arise due to congenital defects, trauma, or chronic irritation. Common Abnormalities Conjunctival Hyperemia: Redness due to dilated blood vessels. Seen in inflammation or irritation. Chemosis: Edema of the conjunctiva. Often due to allergic reactions or trauma. Pinguecula: Yellowish, raised lesion on bulbar conjunctiva near the limbus. Caused by UV exposure and chronic irritation. Pterygium: Triangular fibrovascular growth extending onto the cornea. Associated with UV exposure and dry environments. Conjunctival Cysts: Fluid-filled sacs due to blocked ducts or trauma. 6. Diseases of the Conjunctiva Conjunctival diseases range from infections to immune-mediated and neoplastic conditions. Infectious Diseases Bacterial Conjunctivitis: Etiology: Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae Signs: Purulent discharge, eyelid crusting, conjunctival injection. Viral Conjunctivitis: Etiology: Adenovirus Signs: Watery discharge, follicular reaction, preauricular lymphadenopathy. Chlamydial Conjunctivitis: Etiology: Chlamydia trachomatis Signs: Follicles, mucopurulent discharge, pannus formation. Allergic Conditions Seasonal Allergic Conjunctivitis: Triggered by pollen. Signs: Itching, tearing, chemosis. Vernal Keratoconjunctivitis: Chronic, often in young males. Signs: Giant papillae on upper tarsal conjunctiva, ropy discharge. Autoimmune and Inflammatory Stevens-Johnson Syndrome: Severe mucocutaneous reaction. Signs: Conjunctival scarring, symblepharon. Ocular Cicatricial Pemphigoid: Autoimmune blistering disease. Signs: Progressive conjunctival fibrosis, forniceal shortening. Neoplastic Conditions Conjunctival Intraepithelial Neoplasia (CIN Premalignant lesion. Signs: Gelatinous, leukoplakic lesion near limbus. Squamous Cell Carcinoma: Malignant epithelial tumor. Signs: Nodular, vascularized lesion with surface keratin. Clinical Correlations Red eye is a common presentation and requires differentiation between conjunctival and deeper ocular causes. Discharge type helps distinguish etiology: purulent (bacterial watery (viral ropy (allergic Location of lesions (e.g nasal vs temporal) can hint at environmental causes like UV exposure. message tuhin1986 about this ad |