Signs and Symptoms: Patients presenting with filamentary keratitis generally report ocular discomfort ranging from mild foreign-body sensation to severe pain. Variable tearing and photophobia are likewise present. The condition may be unilateral or bilateral, depending upon the underlying etiology.
Signs include ocular hyperemia particularly in the limbal area, and possibly a pseudoptosis. The hallmark finding is the presence of mucus filaments within the preocular tear film adhering to the corneal surface. These filaments are typically tadpole-shaped (the "head" adheres firmly to the corneal epithelium, while the "tail" floats freely within the tear film). Rose bengal or lissamine green dye makes the filaments more readily visible on biomicroscopy. Other findings may include a reduced fluorescein tear break-up time and a punctate epithelial keratopathy.
Many patients with filamentary keratitis have underlying systemic conditions, particularly connective tissue disorders. The condition may be more common in women and the elderly. Patients with immune deficiencies also are at greater risk.
Pathophysiology: Filamentary keratitis most often accompanies keratoconjunctivitis sicca. Mucous filaments form when the normally soluble mucin component of the tear film becomes corrupted, causing it to precipitate out as particles or strands. Loose, compromised epithelial cells bind with these mucin strands, forming long filaments that adhere to damaged sites on the corneal surface. As the lids open and close with each blink, they tug at the loose end of the filaments, stimulating the pain-sensitive corneal nerves.
Other conditions that can induce a filamentary keratitis include superior limbic keratoconjunctivitis (SLK) of Theodore, prolonged patching following cataract or other ocular surgery, epitheliopathy due to aerosol or radiation keratitis, herpetic keratitis (both simplex and zoster), recurrent corneal erosion, neurotrophic keratitis, bullous keratopathy, and systemic disorders, including diabetes and psoriasis.
Management: Treatment for filamentary keratitis involves eliminating the mucus filaments as thoroughly as possible and addressing the underlying cause. In most cases, management begins with physical removal of the filaments at the slit lamp, using a jeweler's forceps under topical anesthesia. Copious lubrication therapy with artificial tears (preferably non-preserved) helps address the ocular discomfort and rejuvenate the precorneal tear film. Punctal occlusion therapy may help in persistent cases of dry eye.
Manage more severe forms of filamentary keratitis with a high-water (~70%), soft bandage contact lens with prophylactic antibiotic drops bid-tid. Be prepared to manage this condition for prolonged periods. Filamentary keratitis may take weeks or even months to resolve, depending on the etiology and the aggressiveness of therapy. Even after the filaments dissipate, the underlying disease must be controlled or recurrences are likely.
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