contact lens case reports
Controlling Soft Lens Microorganism Contamination
BY PATRICK J. CAROLINE, FAAO, & MARK P. ANDRÉ, FAAO

Microorganism growth refers to a wide range of fungi or yeast formations that can attach to and ultimately infiltrate soft contact lens materials. Under low magnification, the growths appear as brown, pink, orange, black or off-white spots, with fuzzy ill-defined boundaries (Figure 1). Under higher magnification, the lesions exhibit filamentary arms (hyphae) that penetrate and grow throughout the soft lens matrix (Figure 2). Histological staining for fungi reveals that the organisms permeate the entire lens matrix from surface to surface (Figure 3).

Figure 1. Microorganism growth in the periphery of a soft contact lens.	Figure 2. The individual hyphae growing into and out of the lens matrix.

Seeing Spots

Patient LK is a 28-year-old female with a six-year history of quarterly replacement, toric soft lenses. She disinfects her lenses nightly using a hydrogen peroxide-based care system.

The patient presented having noted a white spot on her right lens that she couldn't remove with rubbing. LK first noted the growth two weeks previously, but continued to wear her lenses on a daily basis.

Slit lamp examination showed no conjunctival inflammation and clear corneas OU. The most striking slit lamp observation was a single, elevated, 4.0mm whitish nodual on the right contact lens (Figure 4). High magnification revealed the individual hyphae, confirming the presence of microorganism growth.

Figure 3. The hyphae have infiltrated the entire lens matrix from surface to surface.	Figure 4. Patient LK's right lens with the 4.0mm microorganism growth.

Spotty Lens Disinfection

Microorganism growths commonly result from inadequate lens disinfection or improper lens storage. In this case, the microorganism growth may have resulted from the care regimen.

Laboratory data have shown that a short exposure to hydrogen peroxide (10 minutes or less) effectively neutralizes a wide range of bacteria and viruses present on contact lenses. However, fungi and yeasts are often more challenging for the peroxides, requiring exposure of approximately 60 minutes for full neutralization.

While fungi and yeast contamination of soft lenses is rare, we must properly diagnose the problem, immediately replace the lenses and review proper lens care procedures with the patient. 

Patrick Caroline is an associate professor of optometry at Pacific University and is an assistant professor of ophthalmology at the Oregon Health Sciences University.

Mark André is director of contact lens services at the Oregon Health Sciences University and serves as an assistant professor of optometry at Pacific University.