Patients with eye infections due to RNA viruses present to the ophthalmologist less often than those with infection due to DNA viruses, and these infections most commonly manifest as follicular conjunctivitis associated with an upper respiratory tract infection (Table 9-8). However, certain RNA virus infections may cause pathologic changes in virtually any ocular tissue. For example, influenza virus can induce inflammation in the lacrimal gland, cornea, iris, retina, optic nerve, and other cranial nerves.
The Paramyxoviridae are a family of single-stranded, enveloped RNA viruses that cause numerous human diseases. The most-recognized paramyxoviruses are measles and mumps. The classic triad of postnatally acquired measles (rubeola) consists of cough, coryza, and follicular conjunctivitis. Mild epithelial keratitis may be present. Optic neuritis, retinal vascular occlusion, and pigmentary retinopathy occur less commonly. Measles keratopathy, a major source of blindness in the developing world, typically presents as corneal ulceration in malnourished, vitamin A–deficient children. (For further information on the ocular effects of vitamin A deficiency, see Chapter 8.) A rare and fatal complication of infection with the measles virus, subacute sclerosing panencephalitis (SSPE), occurs in approximately 1 per 100,000 cases, often years after clinically apparent measles.
Table 9-8 RNA Viruses Known to Cause Ocular Surface Disease
Infection with the mumps virus may result in dacryoadenitis, sometimes concurrent with parotid gland involvement. Follicular conjunctivitis, epithelial and stromal keratitis, iritis, trabeculitis, and scleritis have all been reported within the first 2 weeks after onset of parotitis.
Rubella virus (a togavirus), when acquired in utero, may cause microphthalmos, corneal haze, cataracts, iris hypoplasia, iridocyclitis, glaucoma, and salt-and-pepper pigmentary retinopathy. Congenital ocular abnormalities due to rubella are much worse when maternal infection ensues early in pregnancy. Measles, mumps, and rubella are all uncommon in places where childhood vaccination is regularly performed.
Rabies virus (Rhabdoviridae) is an enveloped virus and can be transmitted via corneal transplant. Corneal biopsy and impression cytology have been useful in the early diagnosis of rabies virus infection.
Acute hemorrhagic conjunctivitis (AHC), caused by enterovirus 70 and coxsackievirus A24 variant, and, less commonly, adenovirus 11, is one of the most dramatic ocular viral syndromes. Sudden onset of follicular conjunctivitis associated with multiple petechial hemorrhages of bulbar and tarsal conjunctiva characterizes AHC. The hemorrhages may become confluent and resemble those associated with trauma. Eyelid edema, preauricular adenopathy, chemosis, and punctate epithelial keratitis may be associated with infection. AHC is highly contagious and occurs in large and rapidly spreading epidemics. In approximately 1 out of 10,000 cases due to enterovirus 70, a polio-like paralysis follows; neurologic deficits are permanent in up to one-third of affected individuals.
Retroviruses are positive-sense, single-stranded, enveloped RNA viruses that encode a viral enzyme, reverse transcriptase, that assists in conversion of the single-stranded RNA genome into a circular double-stranded DNA molecule.
The retrovirus of greatest medical importance is human immunodeficiency virus (HIV), the etiologic agent of AIDS. HIV enters the human host via sexual contact at mucosal surfaces, through breastfeeding, or via blood-contaminated needles. Sexually transmitted infection is facilitated by uptake of HIV by dendritic cells at mucosal surfaces. CD4+ T lymphocytes are a primary target of the virus, as are dendritic cells and monocyte-macrophages. Infection of these cell types induces predictable defects of innate and acquired (both humoral and cellular) immunity. Primary viremia results in an infectious mononucleosis-like HIV prodrome, followed by seeding of the peripheral lymphoid organs and development of a measurable immune response. Conjunctivitis may occur during this seroconversion prodrome in a small number of patients and is self-limited. Infected patients may remain otherwise asymptomatic for several years, but CD4+ T lymphocytes are progressively depleted. Clinical immunodeficiency eventually develops.
AIDS-related ocular disorders include HZO, molluscum contagiosum, keratoconjunctivitis sicca, microsporidial keratoconjunctivitis, HIV neuropathy, cryptococcal optic neuritis, retinal microvasculopathy, choroiditis and retinitis due to syphilis, mycobacteria, pneumocystosis, toxoplasmosis, CMV, HSV, and VZV. For more information regarding HIV, see BCSC Section 1, Update on General Medicine, and Section 9, Uveitis and Ocular Inflammation.
Cunningham ET Jr, Margolis TP. Ocular manifestations of HIV infection. N Engl J Med. 1998; 339(4):236–244.
Lai TY, Wong RL, Luk FO, Chow VW, Chan CK, Lam DS. Ophthalmic manifestations and risk factors for mortality of HIV patients in the post-highly active anti-retroviral therapy era. Clin Experiment Ophthalmol. 2011;39(2):99–104.
Zaidman GW, Billingsley A. Corneal impression test for the diagnosis of acute rabies encephalitis. Ophthalmology. 1998;105(2):249–251.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.