A diagnosis of conjunctivitis will typically be made on the basis of clinical signs of hyperaemia, chemosis, ocular discharge, discomfort / pruritus and follicle formation.
A thorough ocular examination and general clinical examination is essential to try and establish an aetiologic diagnosis and to check that any conjunctival inflammation is not a sign of more serious ocular or systemic disease.
Additional diagnostic tests that may be necessary to establish the cause of the conjunctivitis include:
Samples for cytology, culture and sensitivity, and virus isolation / PCR should be taken before the application of topical agents such as fluorescein and local anaesthetics. The Schirmer tear test should also be done before the application of any topicals.