Viral Conjunctivitis (Pharyngoconjunctival Fever & Epidemic Keratoconjunctivitis)

SIGNS AND SYMPTOMS
Most viral infections produce a mild, self-limiting conjunctivitis, but some have the potential to produce severe, disabling visual difficulties. The two most common self-limiting forms of viral conjunctivitis are epidemic keratoconjunctivitis and pharyngoconjunctival fever.

Pharyngoconjunc-tival fever (PCF) is characterized by fever, sore throat and follicular conjunctivitis. It may be unilateral or bilateral. It is caused regularly by adenovirus 3 and occasionally 4 or 7. Corneal infiltrates are rare. The disorder varies in severity but usually persists for four days to two weeks. While the virus is shed from the conjunctiva within 14 days, it remains in fecal matter for 30 days.

Epidemic Keratoconjunctivitis (EKC) often presents as a bilateral, inferior, palpebral, follicular conjunctivitis, with epithelial and stromal keratitis. Subepithelial corneal infiltrates are much more common in EKC than in PCF and are typically concentrated in the central cornea. EKC is regularly caused by adenovirus types 8 and 19.

The key clinical signs of both conditions include: conjunctival injection, tearing, serous discharge, edematous eyelids, pinpoint subconjunctival hemorrhages, pseudomembrane formation and palpable preauricular lymph nodes. In severe cases, conjunctival desiccation causes scarring and symblepharon formation (adherence of the bulbar and palpebral conjunctivas).

Both conditions are highly contagious. Patients will usually report recent contact with someone who had either red eyes or an upper respiratory infection. Both forms tend to start in one eye, then spread to the other eye within a few days. In rare cases, the focal subconjunctival hemorrhages can evolve into acute hemorrhagic conjunctivitis.

PATHOPHYSIOLOGY
Viral conjunctival infections are thought to be caused by airborne respiratory droplets or direct transfer from one’s fingers to the conjunctival surface of the eyelids. After an incubation period of five to 12 days, the disease enters the acute phase, causing watery discharge, conjunctival hyperemia and follicle formation. Lymphoid follicles are elevated, with avascular lesions ranging from 0.2 to 2mm in size. They have lymphoid germinal centers that have responded to an infectious agent.

Adenovirus type 8 can proliferate in the corneal epithelial tissues, producing the characteristic keratitis and subepithelial infiltrates. This, along with the immune response to viral antigens, causes lymphocytes to collect in the shallow anterior stroma, just beneath the epithelium. Sometimes, a conjunctival membrane will form. These are made up of fibrin and leukocytes, and in prolonged cases, of fibroblast and collagen deposits. “Pseudomembranes” are much easier to remove than “true” membranes.

MANAGEMENT
Because EKC and PCF are contagious and self-limiting, the primary treatment once again is patient education. Instruct patients to stay home from work or school until there is absolutely no discharge. Also instruct them not to share utensils, glasses, linens or wash cloths with others.

Medical management can range from cold compresses and artificial tears to topical vasoconstrictors (e.g., naphazoline) and steroids (Vexol, Flarex, Pred Forte) two to four times daily. If a membrane is present, peel it off with a wet, cotton-tipped applicator or forceps. After removal, prescribe a topical antibiotic-steroid combination such as Tobradex or Maxitrol q.i.d. Anti-viral drugs such as Viroptic are ineffective against adenovirus.

Recently, there has been a breakthrough in the management of adenoviral keratoconjunctivitis. Cidofovir (Vistide), an anti-viral drug used intravenously to treat cytomegalovirus retinitis, appears to be effective in adenoviral keratoconjunctivitis. The topical form creates a faulty viral DNA structure. Twice daily instillation is recommended. This topical anti-viral is also possibly effective against herpes simplex and zoster, and Epstein-Barr virus.

CLINICAL PEARLS

Keep your equipment, instruments and chair area meticulously clean to avoid contaminating your patients and staff.
Most practitioners reserve topical steroidal therapy for severe cases (if the infection is on the visual axis and affecting acuity, for example), or recalcitrant cases. EKC infiltrates resolve without scarring the cornea.
Tell patients to expect the symptoms to get worse for about seven to 10 days before getting better, and that the infection won’t completely go away for three to six weeks. Remember to always taper steroids slowly as the condition recedes.