Filamentary Keratitis

Filamentary Keratitis is an eye disorder. IT is a condition in which the strands composed of degenerate epithelial cells and mucus develop on and adhere to the corneal surface pain and foreign body sensation. Filamentary Keratitis is related to an alteration in the components of the film or of ocular surface disease and condition. 

                In Filamentary Keratitis, there is often an increase in the tear film mucus to aqueous ratio. This is commonly due to decrease in aqueous tear production but may also be due to increased production or accumulation of the mucinous component. This alteration in tear film makeup sets the stage for formation of mucoid filaments. Small defects in the corneal epithelium provide an anchoring surface for the filaments. Mucin attaches to the epithelial defect and loose epithelial strands are incorporated into the mucin strand attached to the surface. Filaments may be small sessile adhesions or longer strings that cause irritation and discomfort.

                It is hypothesized that the initial step in development of filamentary keratitis is damage to basal epithelial cells, epithelial basement membrane or Bowman’s layer leading to focal detachments of the epithelial basement membrane. Blinking causes these area of detachments to become elevated leading to irritation, inflammation and increased mucus production. The sites of epithelial damage provide the scaffold for the filaments to develop.

               Patients with filamentary keratitis complain of foreign body sensation. They may also have redness, epiphora, blepharospasm and photophobia.

               Signs include multiple filamentary attachments firmly adherent to the corneal surface, decreased aqueous tears, increased mucin in the precorneal tear film, subepithelial opacities at the base of filaments, or frank corneal epithelial defects. 

               The diagnosis of filamentary keratitis is made clinically with history and slit lamp biomicroscopy. Slit lamp biomicroscopy demonstrates firmly adherent filaments on the corneal surface. A Schirmer test may be helpful in establishing the diagnosis of a dry eye syndrome. 

               The treatment of filamentary keratitis can be challenging and is often chronic. Paramount in the overall treatment of filamentary keratitis is management of underlying conditions such as the dry eye syndromes, medication toxicity, contact lens overuse, and blepharoptosis. 

               First line treatment includes topical therapy with lubricant drops and ointment. Low water-content bandage contact lenses may be helpful temporarily. Acetylcysteine can be used topically to decrease the viscosity of the mucinous component of the tear film.  

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