Introduction
Background
Corneal mucous plaques are abnormal collections of a mixture of mucous, epithelial cells, and proteinaceous and lipoidal material that adhere firmly to the corneal surface. The plaques also may enmesh calcareous granules and bacteria, as well as dust particles and other foreign bodies. The mucous plaques are translucent to opaque and may vary in size and shape from multiple small islands to bizarre patterns that may involve more than one half the corneal surface.
Pathophysiology
An abnormality of the exposed surface of the superficial corneal epithelial cells, excessive mucus formation, and the presence of epithelial receptor sites for the plaque elements predispose to this condition. The normal desquamation of epithelial cells beneath the plaque is retarded, and exfoliating face cells may become incorporated in the plaque. The plaque is formed when high viscosity mucous and proteinaceous material become adherent to the deeper squamous cells of the cornea or even to the Bowman layer through the intercellular spaces, as well as through abnormally formed transcellular aperture and epithelial defects; because of its physiochemical property, the mucous plaque enmeshes the desquamated epithelial cells.
Mucous viscosity may increase as a result of dehydration, an increase in the sialomucin component, or secondary to staphylococcal infection with subsequent liberation of enzymes that lyse the mucoprotein and mucopolysaccharide components of mucous normally produced by conjunctival goblet cells.
Frequency
United States
This condition is seen primarily in patients with keratoconjunctivitis sicca.
Mortality/Morbidity
Eye pain can be present while the plaques are present.
Sex
Keratitis sicca is more common in women than in men.
Age
The incidence of keratitis sicca increases with age.
Clinical
History
- Symptoms associated with corneal plaques include blurring of vision, foreign body sensation, and marked pain.
- Except when severe, these symptoms are often indistinguishable from those of herpes zoster, keratitis, overwear of contact lenses, and keratoconjunctivitis sicca, with or without concomitant Sjögren syndrome, rheumatoid arthritis, or other collagen vascular diseases.
Physical
- Multiple plaques are common and are frequently bilateral. When a plaque has adhered to the cornea, it remains for a few days or weeks; recurrences may appear but seldom are in the same location. Thickened plaques with a dry surface may appear elevated well above the tear film and may even cause dellen formation.
- Other associated findings include the following:
- Chronic blepharoconjunctivitis
- Blepharospasm
- Ciliary or conjunctival injection
- Conjunctival mucoid discharge
- Conjunctival filaments
- Filamentary keratitis
- Decreased corneal sensation
- Mild iritis with or without keratic precipitates
- Corneal epithelial and stromal edema in association with herpes zoster keratitis
- Corneal epithelial defects
Causes
- Corneal mucous plaques occur primarily in patients with keratoconjunctivitis sicca, but they also may be seen with herpes zoster, vernal keratoconjunctivitis and other forms of keratitis, and after local radiation exposure.
- Delayed plaques and pseudodendrites associated with herpes zoster also may be infectious because they are positive for zoster DNA by polymerase chain reaction.
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References
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Doughty MJ. Impact of brief exposure to balanced salts solution or cetylpyridinium chloride on the surface appearance of the rabbit corneal epithelium--a scanning electron microscopy study. Curr Eye Res. Jun 2003;26(6):335-46. [Medline].
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Golubovic S, Parunovic A. Vernal conjunctivitis--a cause of corneal mucoid plaques. Fortschr Ophthalmol. 1986;83(3):272-4. [Medline].
Liesegang TJ. Corneal complications from herpes zoster ophthalmicus. Ophthalmology. Mar 1985;92(3):316-24. [Medline].
Marsh RJ, Fraunfelder FT, McGill JI. Herpetic corneal epithelial disease. Arch Ophthalmol. Nov 1976;94(11):1899-1902. [Medline].
Marsh RJ, Cooper M. Ophthalmic zoster: mucous plaque keratitis. Br J Ophthalmol. Oct 1987;71(10):725-8. [Medline].
Pavan-Langston D, Yamamoto S, Dunkel EC. Delayed herpes zoster pseudodendrites. Polymerase chain reaction detection of viral DNA and a role for antiviral therapy. Arch Ophthalmol. Nov 1995;113(11):1381-5. [Medline].
Shaw EL, Gasset AR. Management of an unusual case of keratitis mucosa with hydrophilic contact lenses and N-acetylcysteine. Ann Ophthalmol. Oct 1974;6(10):1054-6. [Medline].
Tripathi BJ, Tripathi RC, Kolli SP. Cytotoxicity of ophthalmic preservatives on human corneal epithelium. Lens Eye Tox Res. 1993;9:361-74.
Tripathi RC, Tripathi BJ, Silverman RA, Rao GN. Contact lens deposits and spoilage: identification and management. Int Ophthalmol Clin. Spring 1991;31(2):91-120. [Medline].
Further Reading
Keywords
filamentary keratopathy, keratoconjunctivitis sicca
