EXTERNAL EYE DISEASE (Conjunctiva)

Conjunctival Anatomy
■ The conjunctival epithelium includes goblet cells that produce the mucous layer of the tear film.
■ The conjunctival stroma comprises a superfi cial adenoid layer and a deep fi brous layer. The former contains lymphoid tissue that results in follicle formation with appropriate stimuli (it is undeveloped in infants who cannot develop a follicular
response). The tarsal conjunctiva is firmly anchored to the tarsus, resulting in papillae when there is conjunctival infiltration, whereas the bulbar conjunctiva is only loosely
attached to the globe and papillae are not seen except at the limbus.
■ Lymphatics drain to the submandibular and preauricular lymph nodes.
■ The accessory lacrimal glands of Wolfring and Krause are located in the conjunctival stroma at the superior margin of the upper tarsus and the superior fornix, respectively.
■ The meibomian glands open posterior to the grey line.
■ The conjunctiva has comparatively few pain fibres from the trigeminal nerve (ophthalmic division), so pain is poorly localized.

History and Examination

History Key symptoms include redness, surface irritation, itch, discharge, watering, conjunctival swelling, and mildly blurred vision if the tear fi lm is disturbed. More severe visual loss may indicate corneal or other disease.

Examination Systematically examine the lid margin and position, lashes, meibomian gland orifi ces, punctae, fornices, tarsal plates, tear fi lm, limbus, cornea, and conjunctiva. Note and ideally draw the following:
■ Conjunctival injection (hyperaemia): may be diffuse or localized.
■ Subconjunctival haemorrhage: may be fine punctate haemorrhages, larger blotches, or a solid sheet.
■ Discharge: note if serous or watery (viral, toxic aetiology), mucopurulent (bacterial conjunctivitis), or stringy (allergic).
■ Chemosis: oedematous conjunctiva appears milky and may swell beyond the lid margins.
■ Follicles: focal lymphoid hyperplasia over the tarsus produces rounded, avascular, whitish-grey centres with small vessels encircling the base. Differentiate from papillae.
■ Papillae: inflammatory exudates accumulate in the fibrous layer, heaping the conjunctiva into mounds. There is a central tuft of vessels. When small, papillae produce a smooth velvety appearance. ‘Giant papillae’ have a cobblestone appearance. At the limbus, giant papillae appear as gelatinous mounds, usually in the palpebral aperture.
■ Pigment: assess the extent and whether this is associated with increased conjunctival thickness.
■ Pseudomembrane: coagulated exudate that adheres to the tarsal or forniceal conjunctiva. It is easily peeled off and the bed underneath does not bleed, unlike a true membrane. In practice, these may be indistinguishable

■ Symblepharon: identify the position (medial, lateral, or superior fornices) and extent.
■ Punctal orifice: note as normal, occluded, absent, stenosed, or if there is a plug in situ.