WHEN PATIENTS GO FISHING...FOR MUCUS
WILLIAM L. MILLER, OD, MS, PHD, FAAO
Curious behaviors in our patient population can be fairly benign; however, others can cause harm. These behaviors range from trichotillomania to the severe eye rubbing in our keratoconus patients. Actions that form a repetitive behavior are often referred to as body-focused repetitive behavior disorder (BFRBD) (Roberts et al, 2013). Another such behavior is mucus fishing syndrome (MFS). First described in 1981 as self-induced mechanical trauma to the conjunctiva, later work has shed light on the antigenic response created by this trauma, all of which increase mucous production on the ocular surface (McCulley et al, 1985).
Based on symptoms of stringy mucus and ocular irritation, these patients may be confused with those who have run-of-the-mill allergic conjunctival diseases. For this reason, many are prescribed or self-medicate with anti-allergy drops or tear supplements. However, a closer look objectively, in conjunction with a careful history, will uncover the issue of MFS.
Making the Diagnosis
Several ocular surface and lid diseases have been observed to precipitate the actions of MFS. These include dry eye disease, blepharitis, keratoconjunctivitis sicca, chronic allergic conjunctivitis, exposure keratopathy, and foreign bodies (McCulley et al, 1985). Non-specific signs with biomicroscopy may include a reduced tear breakup time and mucous strands.
One clinical key to diagnosis is the use of lissamine green or rose bengal dye, with my preference toward the former. Its use has become commonplace in many practices as a means to diagnose lid wiper epitheliopathy.
MFS will cause large areas of confluent lissamine green staining, typically in the inferior conjunctiva, both bulbar and palpebral.
Because of the pattern observed with MFS, it may be advisable to use liquid lissamine green because application via strip may also be confused with the signs of MFS. Patients who have MFS typically try to physically remove the mucous strands with their finger or fingernail, thus causing mechanical trauma to the conjunctiva and the representative staining. Because other psychological factors may coexist, not all patients will admit to such behaviors (Pokroy and Marcovich, 2003).
Interventional education is the first step in management and can include a frank discussion with patients about the effects of mechanical trauma to the eye. Predisposing factors such as those listed above should also be addressed. Tear supplements as a diluent can be helpful in irrigating the ocular surface of the mucous strands. However, to receive effective treatment, frequent and copious instillation should be prescribed.
In patients who do not receive relief with tear supplements, a mucolytic agent such as N-acetylcysteine drops (5% or 10%) should be initiated. N-acetylcysteine will break chemical bonds in the mucus, causing it to break down; it also may produce some anti-inflammatory properties (Slagle et al, 2001). Dosing at four times daily for at least a month would be appropriate, which is similar to what is typically done in cases of filamentary keratitis. Although not commercially available, it can be formulated at a compounding pharmacy. The typical shelf life is 30 days because the medication is formulated without a preservative. If an allergic component is suspected as a causative factor, an antihistamine/mast cell stabilizer can be started.
Often, the predisposing factors for MFS may include dry eye disease, and further progressive therapy may include cyclosporine 0.05% used twice daily (Kaçmaz et al, 2010). Another recently approved topical medication for dry eye disease, lifitegrast 5% prescribed twice daily, may also be a new adjunct in the attempt to prevent further exacerbations of MFS. Our goal is to break the cycle of mechanical trauma with long-term management to prevent any recurrences of the cycle. CLS
For references, please visit www.clspectrum.com/references and click on document #250.
Dr. Miller is an associate dean for academic affairs and professor at the Rosenberg School of Optometry, University of the Incarnate Word. He has received research funding from Alcon and SynergEyes and travel funding from Alcon. You can reach him at firstname.lastname@example.org.