contact lens care
Soft
Contact Lens Deposition — Part I
BY
SUSAN J. GROMACKI, OD, MS, FAAO
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Figure
1. Lipid deposition on a soft contact lens. Photos courtesy of Dr. Ron Watanabe.
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Soft lens complications are often a result of
contact lens deposition. The use of disposable lenses — especially daily and
two-week replacement modalities — has helped in decreasing deposition
and the problems associated with it. When using yearly or three-month replacement
modalities, however, patients must perform proper lens care to provide a clean lens
surface. Hydrogel lenses deposit secondary to their hydrophilic surface, patient
tear film, environment and lens handling. Here are some common types of soft contact
lens deposits and how to manage them.
Protein
Deposits
One of the more common deposits, protein deposits originate primarily
from albumin, globulin and lysozyme in the tears. A protein deposit has an opaque,
white filmy appearance and may have cracks when the film is thick. It's found primarily
on the front surface of soft contact lenses and on both surfaces of GP lenses. Deposition
begins immediately after lens application. The deposits may bind solution preservatives.
Protein deposition is most common in high-water-content hydrogels, followed by low-water-content
HEMA materials. Silicone hydrogels tend to accumulate protein the least.
Practitioners should direct patients prone to heavy protein deposition
to daily disposables. If this can't be done, recommend an enzymatic cleaner once
each week or more. Extended wear patients should switch to daily wear. It's also
helpful to refit into a more protein deposit-resistant material such as silicone
hydrogel.
Lipid Deposits
Lipid deposition has a smeared, greasy whitish appearance (Figure
1). The lipid arises from the meibomian glands of the lids. Patients more prone
to deposition include those with tear film potassium deficiency, dry eye, high fat
diets and high alcohol consumption. Silicone hydrogel materials tend to accumulate
more lipids than some conventional materials. Management includes thoroughly rubbing
or rinsing lenses with solution; using an alcohol-based daily cleaner, which dissolves
lipids; and/or using lenses with a two-week or less replacement schedule.
Microorganisms
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Figure 2. Close-up of a fungus imbedded in
a soft contact lens. |
These are gray, black, brown or white growths in the lens matrix.
Microorganisms are usually fungi or yeast and appear in a filamentary pattern (Figure
2). They're common in patients who neglect daily disinfection or who use non-preserved
saline, high-water-content lenses and/or lenses dam-
aged or deposited with protein.
Lenses contaminated with microorganisms need to be replaced. Careful
patient instruct-
ion is necessary regarding good personal hygiene and proper
daily disinfection. It's also important to avoid prolonged lens storage without
disinfecting lenses.
Dr. Gromacki has served
as a faculty member at the University of Michigan Department of Ophthalmology
and Visual Sciences.
Contact Lens Spectrum, Issue: February 2006