and Contacts: A Good Match?
should I know before fitting a diabetic patient with contact lenses?
Caution is your watchword. No known well-controlled clinical studies
specifically address the relationship between diabetes and contact
lens-induced complications. That's why there are varying opinions
Diabetic patients will potentially have more problems than normal
patients will. Diabetics are known to be poor healers. They also
have decreased corneal sensitivity, which increases their chances
of a loose epithelium. A weakened immune system makes these patients
more prone to infections in general, and specifically in the eye
due to this decreased corneal sensitivity and poor healing.
Even diabetic patients not wearing contact lenses tend to be slower
to heal, If the corneal sensitivity gets to the point where the
patient becomes hypesthetic, a neurotrophic ulcer develops. This
is a poor-healing lesion. Diabetics have a high preponderance of
neurotrophic ulcers. The practitioner exercises more caution with
younger patients, and those who tend to have Type 1 insulin-dependent
diabetes (although patients with Type 2 diabetes may also encounter
complications). By determining how well Type 1 patients control
their diabetes, you can learn how compliant they'll be with contact
lenses, she says. Find out how often the patient checks his glucose
and what the readings are at those times, and if the patient is
sensitive to hypoglycemia.
Insensitivity to extremely low blood glucose levels is one indication
of advanced diabetes. Diabetes affects all layers of the cornea
as well as the tear film and conjunctiva. These changes are surprisingly
similar to those which long-term contact lens wear causes. This
suggests that both effects are a generalized corneal response to
metabolic stress. Diabetics who wear contact lenses get a double
whammy, and their corneas may have less functional reserve to handle
stress and stave off infection.
need to determine if the combination of corneal changes caused by
both the disease and lens wear will significantly alter the integrity
and physiology of the cornea. Take a careful case history and a
good look with the slit lamp. Ask the patient if he or she has a
history of corneal erosions. Check for corneal thickening, edema
or striae during a morning appointment. These conditions persist
in a diabetic patient, whereas non-diabetics exhibit clear eyes.
Endothelial cells may be abnormal in size and shape, leading to
increased corneal thickness and persistent stromal edema.
Counsel the patient on the risk factors of contact lens wear. Require
follow up visits between two and three times a year. Limit wearing
time and make sure the patient keeps his or her lenses clean. In
general, rigid gas permeable lenses and daily wear have a lower
incidence of infection than soft lenses or extended wear. Most experts
feel that practitioners should stress daily wear of contact lenses
only. Going with an RGP lens in some cases might be best to minimize
complications. Soft lenses and hypoxia may exacerbate endothelial
cell swelling and stromal edema
The best road to take: Consider each patient separately, rather
than make sweeping generalizations about diabetic patients and contact