Conjunctival diseases

• Conjunctiva


  Transparent mucous membrane that lines the inner surface of the eyelids and the anterior surface of the globe, terminating at the corneoscleral limbus
• Conjunctiva


  • Richly vascular, supplied by the anterior ciliary and palpebral arteries
  • Dense lymphatic network, with drainage to the preauricular and submandibular nodes corresponding to that of the eyelids
• Anatomical divisions of the conjunctiva


  • Palpebral conjunctiva
  • Forniceal conjunctiva
  • Bulbar conjunctiva
• Palpebral conjunctiva


  Starts at the mucocutaneous junction of the lid margins and is firmly attached to the posterior tarsal plates
• Forniceal conjunctiva


  Loose and redundant
• Bulbar conjunctiva


  Covers the anterior sclera and is continuous with the corneal epithelium at the limbus
• Limbus

  • Radial ridges form the palisades of Vogt, the likely reservoir of corneal stem cells
  • Stroma is loosely attached to the underlying Tenon capsule, except at the limbus, where the two layers fuse
• Plica semilunaris


  Semilunar fold present nasally, medial to which lies a fleshy nodule (caruncle) consisting of modified cutaneous tissue
• Types of conjunctival discharge


  • Watery discharge (serous exudate and tears)
  • Mucoid discharge
  • Mucopurulent discharge
  • Moderately purulent discharge
  • Severe purulent discharge
• Watery discharge


  Occurs in acute viral or acute allergic conjunctivitis
• Mucoid discharge


  Typical of chronic allergic conjunctivitis and dry eye
• Mucopurulent discharge


  Typically occurs in chlamydial or acute bacterial infection
• Moderately purulent discharge


  Occurs in acute bacterial conjunctivitis
• Severe purulent discharge


  Suggestive of gonococcal infection
• Types of conjunctival reaction


  • Diffuse, beefy-red hyperaemia more intense away from the limbus (bacterial infection)
  • Limbal injection (ciliary injection of iridocyclitis)
  • Haemorrhages (viral conjunctivitis, severe bacterial conjunctivitis)
  • Chemosis (conjunctival oedema)
• Chemosis


  Translucent swelling that may protrude through the eyelids, indicating a hypersensitivity response or severe infective conjunctivitis
• Causes of subacute or chronic chemosis


  • Local (e.g. thyroid eye disease, chronic allergic conjunctivitis, ocular or eyelid surgery, trauma)
  • Increased systemic vascular permeability (e.g. allergic conditions, infections including meningitis, vasculitis)
  • Increased venous pressure (e.g. superior vena cava syndrome)
• Pseudomembranes


  Consist of coagulated exudate adherent to the inflamed conjunctival epithelium, can be peeled away leaving the underlying epithelium intact
• True membranes


  Involve the superficial layers of the conjunctival epithelium so that attempted removal leads to tearing
• Causes of pseudomembranes and true membranes


  • Severe adenoviral conjunctivitis
  • Gonococcal and some other organisms
• Follicles


  • Multiple, discrete, slightly elevated lesions resembling translucent grains of rice, most prominent in the fornices
  • Blood vessels run around or across rather than within the lesions
  • Histology shows a subepithelial lymphoid germinal centre with central immature lymphocytes and mature cells peripherally
• Causes of follicles


  • Viral and chlamydial conjunctivitis
  • Parinaud oculoglandular syndrome
  • Hypersensitivity to topical medications
  • Folliculosis (normal finding in childhood)
  • Follicles in the fornices and at the margin of the upper tarsal plate (normal in adults)
• Papillae


  • Develop only in the palpebral conjunctiva and in the limbal bulbar conjunctiva where it is attached to the deeper fibrous layer
  • In contrast to follicles, a vascular core is present
  • Micropapillae form a mosaic-like pattern of elevated red dots
  • Macropapillae (1 mm) develop with prolonged inflammation
  • Limbal papillae have a gelatinous appearance
  • Histology shows folds of hyperplastic conjunctival epithelium with a fibrovascular core and subepithelial stromal infiltration with inflammatory cells
  • Late changes include superficial stromal hyalinization, scarring and the formation of crypts containing goblet cells
• Causes of papillae


  • Bacterial conjunctivitis
  • Allergic conjunctivitis
  • Chronic blepharitis
  • Contact lens wear
  • Superior limbic keratoconjunctivitis
  • Floppy eyelid syndrome
• Lymphadenopathy


  The most common cause is viral infection, but it may also occur in chlamydial and severe bacterial conjunctivitis (especially gonococcal) and Parinaud oculoglandular syndrome, typically affecting the preauricular site