Scientific Subjects

Diabetes and Contacts: A Good Match?

What 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 among clinicians.
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.

You 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 lenses.




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