The eye is vulnerable to disease caused by common viruses such as adenovirus and herpes zoster virus that are known to infect various parts of the body. Primary or secondary (one that spreads from another location in the body) viral eye infections can cause inflammation to the superficial or deeper structures of the eye, leading to a number of transient or permanent complications.
Herpes Zoster Infections
The herpes zoster virus (otherwise known as shingles) is the virus that causes chicken pox. After lying dormant in nerve cells for a period of time, it may become active and produce a rash and blistering sores on the skin. If the virus affects the nerves that supply the eye, it can lead to a variety of infections of the eye and eyelid. According to St. Luke's Eye Center, herpes sores on the nose are a sign of likely eye infection. Infection commonly causes an inflammation and scarring of the cornea (the transparent dome covering the front of the eye) or a condition known as herpetic keratitis. According to the University of Illinois at Chicago Department of Ophthalmology, the virus usually heals without scarring if infection is limited to the superficial layer of the cornea; however, if it infects deeper tissue, it can cause corneal scarring, vision loss or blindness.
Herpes zoster infections may also commonly cause conjunctivitis (inflammation of the conjunctiva--the thin, transparent covering of the eye) and iritis (inflammation of the iris, or colored part, of the eye). Less commonly, they may result in infection of the middle layer of the eye (herpes uveitis) or of the retina (herpes retinitis).
Chronic herpes outbreaks involving the eye can lead to double vision, scarring of the eye and eyelids, cataracts (clouding of the lens of the eye that dims vision and may require surgical treatment) and glaucoma (damage to the optic nerve and fibers of the retina that can lead to permanent vision loss or blindness).
Cytomegalovirus
The cytomegalovirus (CMV) is related to the herpes virus and is commonly found in most people. While most peoples' immune systems are strong enough to suppress infection from CMV, immunosuppressed individuals are at risk of developing the disease throughout the body and the eye. According to St. Luke's Eye Center, CMV is the most common virus to affect those with HIV. In roughly 30 percent of cases, it causes damage to the retina (called CMV retinitis). Complications from CMV infection include retinal detachment, hemorrhages in the eye, permanent vision loss due to inflammation of the retina and blindness.
Viral Conjunctivitis
Viral conjunctivitis is a contagious infection and inflammation of the conjunctiva. According to Merck Manuals Online Medical Library, acute conjunctivitis is usually caused by adenovirus, and it may occur along with the common cold or other body-wide infections. Typical symptoms of viral conjunctivitis usually include watery discharge, eye irritation and dilated blood vessels visible throughout the white part of the eye. Some people may experience sensitivity to light and a sensation that there is a foreign body in their eye. Viral conjunctivitis usually lasts one to three weeks and is treatable with warm or cool compresses and prescription eye drops or topical treatments.
