February 2014 Online Photo Diagnosis
By William Townsend, OD, FAAO
When we initially saw this individual in a very early stage of the disease, she appeared to have a garden-variety viral keratoconjunctivitis. But a few days later, she returned complaining of reduced vision and severe pain, and she demonstrated tender, enlarged lymphadenopathy in multiple sites; at that point, it was evident that her keratoconjunctivitis was a more severe form. We ultimately revised our diagnosis to epidemic keratoconjunctivitis (EKC).
On subsequent evaluation, we noted the formation of a dense, membranous exudate overlying the inferior tarsal conjunctivae of both lids. After instilling a topical anesthetic, we used sterile forceps to gently peel the membranes away from the conjunctiva. The underlying conjunctival surface immediately began to bleed. After removing the membranes, we instilled a topical antibiotic/steroid suspension and instructed the patient to instill the medication every four hours OD and OS. Ensuing visits revealed gradual healing of the conjunctival surface with resolution of the hemorrhages.
Adenoviruses are non-enveloped, double-stranded DNA viruses.1 Human adenoviruses are highly contagious and can infect the mucosal tissues of the eye, gastrointestinal tract, respiratory tract, and urinary tract.2 They are divided into six subgroups (A to F); subgroups B, C, D, and E can cause viral conjunctivitis, but only D serotypes are associated with the more severe form, i.e., EKC.2
Reviewing the literature over the past four decades reveals conflicting and sometimes confusing information regarding the inflammatory exudates that develop on the conjunctival surface in cases of severe EKC.3 Some authors refer to them as membranes, while others identify them as pseudomembranes.4 Pseudomembranes are characterized by an exudate that contains fibrin and lacks blood vessels or lymph vessels. Because of their composition, removal of these lesions from the conjunctiva does not result in bleeding.4
In contrast, true (formed) membranes are exudates consisting of a fibrin matrix containing neutrophils, macrophages, pro-angiogenic factors, and vascular channels that may represent recently formed capillaries. This structural arrangement is thought to explain the bleeding noted after removal of conjunctival membranes (Video 1).
Failure to remove true membranes in EKC may ultimately lead to the development of symblepharon. Dawson et al4 and Chintakuntlawar and Chodosh5 have suggested that in cases of EKC, the difference between the development of pseudomembranes versus true membranes may be the degree and intensity of the inflammatory response.
1. Mims C, Playfair J, et al (1993). Medical Microbiology. London: Mosby-Year Book Europe Limited.
2. Wu E, Trauger SA, et al. Membrane cofactor protein is a receptor for adenoviruses associated with epidemic keratoconjunctivitis. J Virol. 2004 Apr;78(8):3897-3905.
3. Laibson PR, Green WR. Conjunctival membranes in epidemic keratoconjunctivitis. Arch Ophthalmol. 1970 Jan;83(1):100-102.
4. Dawson CR, Hanna L, Togni B. Adenovirus type 8 infections in the United States. IV. Observations on the pathogenesis of lesions in severe eye disease. Arch Ophthalmol. 1972 Mar;87(3):258-268.
5.Chintakuntlawar AV, Chodosh J. Cellular and tissue architecture of conjunctival membranes in epidemic keratoconjunctivitis. Ocul Immunol Inflamm. 2010 Oct;18(5):341-345.