The Conjunctiva: Diseases and Tumours

Published on 08/03/2015 by admin

Filed under Opthalmology

Last modified 08/03/2015

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3 The Conjunctiva: Diseases and Tumours

The conjunctiva is the transparent mucous membrane lining the inner surfaces of the eyelids; it is reflected over the anterior episclera and sclera before terminating at the limbus, where it is continuous with the corneal epithelium. In the embryo the conjunctiva develops from the ectoderm covering the lids and surface of the globe, and is formed during the third month of intrauterine life as the eyelids grow together. A healthy conjunctiva is essential for normal ocular function and together with the eyelids it is critical in maintaining a suitable environment for the cornea to function as the primary refractive element of the eye. Its mucous and accessory lacrimal secretions are important components of the precorneal tear film, and their deficiency gives rise to tear film instability and poor wetting of the corneal surface, which may lead eventually to pathological changes in the cornea. It follows, therefore, that examination of the whole conjunctival surface is necessary in order to interpret signs in the cornea, and an understanding of conjunctival pathology is a prerequisite to the effective management of many corneal disorders. As part of its function in maintaining the corneal environment, the conjunctiva also has an important role in defending the eye against a variety of agents.

THE NORMAL CONJUNCTIVA

PATHOLOGICAL CHANGES OF THE CONJUNCTIVA

The conjunctiva may undergo a variety of changes as a result of disease. Recognition of the types of change may give valuable information about the aetiology of the disease, but the conjunctiva has a limited repertoire of pathological responses and great care should be exercised before attributing particular conjunctival signs to a diagnosis. It is rare for pathognomic findings to occur in the conjunctiva: diagnosis should always be based on the history and on examination of the adjacent tissues such as the lids and cornea in addition to the conjunctiva.

Causes of papillary and follicular conjunctivitis are listed in Table 3.1.

Table 3.1 Causes of papillary and follicular conjunctivitis

Papillae Follicles
Allergic conjunctivitis; atopic, vernal, seasonal or perennial Virus infection: adenovirus, herpes simplex, molluscum contagiosum
Topical preparations: drops, preservatives, ointments Cnlamydial infection: trachoma (subtypes A–D), paratrachoma (subtypes E–K)
Chronic 1irritation: giant papillary conjunctivitis, superior limbic conjunctivitis, dry eyes Drug induced: glaucoma, antiviral drops
  Lymphoid disease: reactive hyperplasia, conjunctival lymphoma