Differential diagnosis and management of Conjunctivitis.

Conjunctivitis: Differential Diagnosis and Management

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Introduction

A healthy conjunctiva is necessary for the maintenance of a healthy cornea and thus the visual acuity of the eye. The conjunctiva contributes to the tear film which has three layers:

·         (Inner) mucous – adherence to the cornea (from the conjunctiva)

·         (Middle) aqueous – wetting agent (from the lacrimal glands)

·         (Outer) oil – prevention of evaporation (Meibomian and Zeis glands)

Infections of the conjunctiva can spread to the cornea and can cause a perforation, e.g., gonococcal infection. Allergic conjunctivitis or limbal catarrh can spread over the cornea. ‘Cobblestones’ form under the lid on the tarsal conjunctiva, and can cause corneal ulcers. Chemical injury to the limbal area can destroy the stem cells that are responsible for the re-epithelialization of the cornea. Dryness will damage the surface of the cornea

Diagnosis and Management

Conjunctivitis may be

·         infective–bacterial, viral or chlamydial

·         allergic

Bacterial Conjunctivitis

The common organisms are the Staphylococcus aureus, Staphylococcus epidermidis, Group A Streptococcus and Streptococcus pneumoniae. Other organisms are Haemophilus influenzae, Pseudomonas and Escherichia coli.¹ Moraxella lacunata causes an angular conjunctivitis with a whitish discharge at the outer canthus. The spectrum of organisms causing conjunctivitis varies around the world.

Symptoms and signs: Abundant, purulent secretions, eyelids stuck together on waking,

Unilateral infection at onset which may later spread to other eye.

Bacterial infection of the conjunctival sac can be secondary to discharge resulting from a foreign body, dry eye, trichiasis, or lacrimal mucocele. It is necessary to examine the lid margins, evert the upper lid, and look for discharge from the lacrimal puncta.

Treatment:  

·        Clean eyes 4 to 6 times/day with clean water or 0.9% normal saline.

·        Eye drops are more practical than ointments as vision is not blurred with drops. They can be easily and frequently applied. However, most primary clinics will have tetracycline eye ointment as their ophthalmic antibiotic, so this should be used. Chloramphenicol and gentamicin are both broad spectrum antibiotics and often available. Initially the drops should be instilled every 10 minutes until the infection is under control.

·        The eye should not be padded.

·        NEVER use corticosteroids drops or ointment.

Viral Conjunctivitis

Symptoms and signs: Watery discharges, red eye, itch.

Treatment:  

·        Clean eyes 4 to 6 times/day with clean water or 0.9% normal saline

·        Viral conjunctivitis is a self-limiting disease and does not require antibiotic treatment unless a secondary bacterial infection occurs.

·        Antiviral, e.g., acyclovir, are not indicated.

 Allergic (Vernal) Conjunctivitis

Symptoms and signs: Red eyes, excessive lacrimation, intense itching.    

Treatment:

·       Clean eyes 4 to 6 times/day with clean water or 0.9% normal saline

·        Antihistamine eye drops

·        Oral antihistamines (promethazine or chlorphenarimine).

·        Topical steroids such as prednisolone eye drops are frequently used and although complications are uncommon it is vital to be aware of them. For example, corneal ulcers can be made worse.

·        Cromolyn sodium eye drops 4%

Conjunctivitis: Bacterial, Viral and Allergic:

Type	Symptoms and Signs	Management	Prevention
Bacterial Conjunctivitis	Red eye Discharge of pus Pain/Photophobia (especially if secondary corneal involvement)	Chloramphenicol 0.5% eye drops Gentamicin 0.3% eye drops Tetracycline 1% eye ointment Intensive instillation for first day or until symptoms and signs reduce	Personal hygiene: hand washing Correct cleaning and disinfection of instruments between examinations Contact lens hygiene
Viral Conjunctivitis	Red eye Watery discharge Itch/Irritation/ Sub conjunctival hemorrhages	Cold compresses to relieve discomfort	Personal hygiene: hand washing Correct cleaning and disinfection of instruments between examinations
Allergic Conjunctivitis	Red eye Lacrimation +++ Itch/Irritation Trantas spots Cobblestones Mucus build up	Reassurance Antihistamines (eye drops or orally) Steroid eye drops Cromolyn sodium 4% eye drops	Avoid allergens

Prevention of Conjunctivitis

Prevention of infective conjunctivitis relies primarily on good personal hygiene.

·         Bacterial conjunctivitis is uncommon but can be spread by the hands or from upper respiratory tract infections.

Gonnoccal infection is transmitted from the genital tract or urine to the eye by hands. This is a serious breach of normal hygiene.

Ophthalmia neonatorum can be prevented by the use of povidone iodine drops, tetracycline eye ointment or other antiseptics or antibiotics at birth.

·         Viral conjunctivitis, in particular adenovirus, can sweep through a community or an institution such as a school very quickly. This is highly infectious and needs to be controlled by the enforcement of strict hygiene standards – towels, face cloths, hands.

·         Prevention of allergic conjunctivitis is not possible unless the patient is able to change his or her environment or job or identify the allergen causing the allergy and remove it, e.g., pollen, animal fur. Drugs can cause an allergy that is reversed by stopping the drug. Atropine, neomycin and eye drop preservatives are particularly common causes of such drug reactions.