Corneal Mucous Plaques 

Updated: Jun 14, 2016
Author: Robert H Graham, MD; Chief Editor: Hampton Roy, Sr, MD 

Overview

Background

Corneal mucous plaques are abnormal collections of a mixture of mucus, 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.[1]

Pathophysiology

An abnormality of the exposed surface of the superficial corneal epithelial cells, excessive mucous 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 mucus 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 mucus normally produced by conjunctival goblet cells.

Epidemiology

Frequency

United States

Corneal mucous plaques are 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.

 

Presentation

History

Symptoms associated with corneal plaques include blurred 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 are seldom 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[2, 3]

  • 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.[2, 4, 5]

Delayed plaques and pseudodendrites associated with herpes zoster also may be infectious because they are positive for zoster DNA by polymerase chain reaction.[6]

 

DDx

Differential Diagnoses

 

Workup

Other Tests

Fluorescein, rose bengal, or lissamine green staining, along with Schirmer testing, can be helpful in making the diagnosis of dry eye syndrome.

 

Treatment

Medical Care

The use and concentration of topic mucolytic agents, such as acetylcysteine, should be individualized to the severity of the disease and symptoms. Topically applied 10-20% acetylcysteine drops 1-4 times daily can rapidly loosen the adherent plaque by dissolving the mucoid component. Continued therapy may result in plaque recurrence. Plaques may still occur in patients receiving acetylcysteine treatment, but the mucous adherence is usually weaker and the plaques are shorter-lived than those formed in the absence of mucolytic therapy.

Mucous plaques causing more severe symptoms may be mechanically retrieved by scraping with a spatula, pulling with forceps, or debriding with a cotton swab or Weck-cel sponge. A bandage soft contact lens applied to the cornea may both enhance patient comfort and prevent recurrence. However, because of frequently associated keratoconjunctivitis sicca, tear film abnormalities, and contact lens deposit formation, the bandage contact lens may need frequent replacement or cleaning.[7] Plaques also may recur if the bandage contact lens is discontinued.

Staphylococcal blepharitis may predispose patients to corneal mucous plaque formation. Therefore, when appropriate, treatments should include adequate control of associated local microbial infection and colonization.

Artificial tear preparations may be indicated for the treatment of dry eye. In the presence of filamentary keratitis and the formation of excessive mucus, hypotonic artificial tear substitutes (rather than the viscous type of tear substitutes) may be combined with acetylcysteine. The use of preservative-free tear substitutes or lubricants is preferable due to the epithelial toxicity exhibited by many ophthalmic preservatives, such as benzalkonium chloride, chlorobutanol, and thimerosal.[8]

Delayed plaques and pseudodendrites associated with herpes zoster may be responsive to certain antiviral therapy.[6]

Excimer laser phototherapeutic keratectomy has been demonstrated as a useful adjunct to the treatment of shield-shaped keratoconjunctivitis.[9, 10]

Consultations

In patients with Sjögren syndrome, a rheumatology consult may be helpful.

 

Medication

Medication Summary

The goals of pharmacotherapy are to reduce morbidity and to prevent complications.

Topical collagenase inhibitors

Class Summary

Used to inhibit lytic effect of collagenase.

N-acetylcysteine (Mucomyst 20%)

Action is somewhat unclear. Mucomyst 20% is diluted to a 10% solution with artificial tears. Use of this medication dissolves mucous plaques.

 

Follow-up

Complications

Corneal plaques may cause eye pain and blurred vision during their presence. They also can be associated with epithelial defects.

Prognosis

Corneal plaques generally only last a few days to a few weeks; however, they can reoccur but usually not in the same location.