Contact Lens Case Reports

Melting Filaments with Soft Contact Lenses

By Patrick J. Caroline, FAAO, & Mark P. André, FAAO

Filaments appear as gelatinous refractile objects that firmly attach to the anterior surface of the cornea. They can occur singly or in great numbers, and the process can be acute or chronic.

A Closer Look at Filaments

The presence of filaments on the ocular surface should be considered a sign rather than a disease. Mucous filaments are predominantly composed of gelatinous mucin that forms round spheroids on the corneal surface where the tear film has become compromised. Epithelial filaments occur when excess mucus is present (as in cases of ocular surface disease). They are composed of desquamated epithelial cells, lipids, and other foreign matter that become entrapped in the mucus, creating particles or strands.

The filament “heads” adhere firmly to the corneal epithelium, while the “tails” float freely within the tear film. During blinking, the lids tug at the “tails” of the filaments, stimulating the painsensitive corneal nerves. Patients presenting with filamentary keratitis generally report ocular discomfort ranging from mild foreign body sensation to severe pain. Variable tearing and photophobia are also present.

Managing Recurring Filaments

Our patient was a 48-year-old male who was referred to our clinic for contact lens fitting post-penetrating keratoplasty OS. On initial presentation, the patient complained of a slight foreign body sensation OS. Slit lamp examination showed the transplant to be clear with no sutures present. The only abnormal finding was the presence of two mucous filaments at the graft/host interface at 7 o’clock (Figure 1). One of our optometric physicians removed the filaments, and the patient was instructed to begin preservative-free artificial tears every two hours. He returned for follow up in one week with two new filaments in the same positions as the previous week.

Clinical experience has taught us that filaments quickly “melt away” beneath soft contact lenses, beginning within minutes of lens application. Because the patient had relatively low (2.50D) postoperative regular astigmatism, we elected to fit a Biofinity Toric (CooperVision) soft lens. Figure 2 shows the mucous filaments five minutes after the initial lens application. After one week of lens wear, the patient reported excellent comfort. Slit lamp examination showed complete resolution of the filaments (Figure 3).

Figure 1. Mucous filaments following penetrating keratoplasty.

Figure 2. Filament collapse five minutes post-soft lens application.

Figure 3. The absence of filaments following one week of soft contact lens wear.

This case illustrates how soft contact lenses can be used to “melt” and prevent filaments in some patients who have ocular surface anomalies. CLS

Patrick Caroline is an associate professor of optometry at Pacific University. He is also a consultant to Contamac. Mark André is an associate professor of optometry at Pacific University. He is also a consultant for CooperVision.