Description

• Eye infection (blepharitis, conjunctivitis, keratitis, stromal keratitis, uveitis, retinitis, glaucoma, or optic neuritis) caused by herpes simplex virus (HSV) types 1 or 2 or varicella-zoster virus (VZV, also known as human herpes virus type 3 [HHV3]).
  • HSV: most often affects the cornea (herpes keratoconjunctivitis); HSV1 > HSV2; can be further divided into primary and recurrent
  • VZV: When VZV is reactivated and affects the ophthalmic division of the 5th cranial nerve, this is known as herpes zoster ophthalmicus (HZO), a type of shingles.
• System(s) affected: eye, skin, central nervous system (CNS) (neonatal)

Epidemiology

Predominant age: HSV—mean age of onset 37.4 years but can occur at any age, including primary infection in newborns; VZV usually advancing age (>50 years)

Incidence

• HSV keratitis: In the United States, approximated at 18.2 per 100,000 person-years. Incidence is 1.5 million per year worldwide (1).
• VZV: 1 million new cases of shingles per year in the US; 25–40% develop ophthalmic complications. Temporary keratitis is most common.

Prevalence

• Ocular HSV prevalence estimated at 500,000 in the United States (1)
• VZV: Prevalence of herpes zoster infection is 20–30%. Ocular involvement in 50% if not treated with antivirals (2); overall lifetime prevalence of HZO: 1%

Etiology and Pathophysiology

• HSV and VZV are Herpesviridae dsDNA viruses.
• HSV: primary infection from direct contact with infected person via saliva, genital contact, or birth canal exposure (neonates)
  • Primary infection may lead to severe disease in neonates, including eye, skin, CNS, and disseminated disease.
  • Recurrent infection is more common overall cause of herpetic eye infections.
• VZV: Primary infection from direct contact with infected person may cause varicella (“chickenpox”) and/or lead to a latent state within trigeminal ganglia.
  • Reactivation of the virus may affect any dermatome (resulting in herpes zoster or “shingles”), including the ophthalmic branch (HZO).

Risk Factors

• HSV: personal history of HSV or close contact with HSV-infected person
  • General risk factors for reactivation: stress, trauma, fever, UV light exposure, other viral infections
  • Risk factors for HSV keratitis: UV laser eye treatment, some topical ocular medications such as prostaglandin analogues and primary/secondary immunosuppression
• HZO
  • History of varicella infection, advancing age (>50 years), sex (female > male), acute/painful prodrome, trauma, stress, immunosuppression (1),(3)

General Prevention

• Contact precautions with active lesions (HSV and VZV)
• VZV can be spread to those who have not had chickenpox, are not immunized, or are not immune.
• Varicella recombinant zoster vaccine (Shingrix) (VZV only): 2 doses 2 to 6 months apart recommended by the CDC for all persons age 50 years and older; preferred over older vaccine (Zostavax), which can still be used for persons age >60 years unable to take Shingrix, although no longer available in the United States (4)
  • Do not give varicella vaccine during an acute infection.
• Acyclovir can be used prophylactically to prevent recurrence of ocular HSV.
• HSV immunization currently being researched (1)

Pregnancy Considerations

• Pregnant women without history of chickenpox should avoid contact with persons with active zoster.
• Pregnancy increases risk of recurrence of HSV/VZV.
• Shingrix and Zostavax vaccinations are both contraindicated during pregnancy.

Commonly Associated Conditions

Primary and secondary immunocompromised states