Pigment on the surface of lenses poses risks

October 11, 2016
Study finds contact lens with pigment on the surface created more inflammation and conjunctival redness than other lens types.

Excerpted from page 53 of the October 2016 edition of AOA Focus.

Vanity has a price, and when it comes to wearing tinted contact lenses, it's the eyes that often pay the bill.

A study published in the journal Optometry & Vision Science evaluated health markers in the eye after subjects wore a conventional clear lens, a tinted lens with the pigment embedded within the lens, and a tinted lens with the pigment on the surface. The results suggest that pigment on the surface could be harmful to your eyes.  

After subjects wore each lens for eight hours, researchers evaluated the condition of the ocular surface and harvested tear samples to measure inflammation markers.

They found a significant difference between each lens type:

  • The clear lens left the ocular surface in the best condition
  • The two tinted lenses created more inflammation and conjunctival redness than the clear lens.
  • The model with pigment on the surface of the lens created a far worse effect in the eye than the other two lenses, with the greatest conjunctival redness, limbal redness, corneal staining and conjunctival staining.

In order to determine a defined metric, scientists measured the amount of cytokines—small proteins that are released during an immune response—within the tears of subjects. The lenses with surface pigments contained 122% more cytokines than the nontinted lenses and 71% more than the lenses with embedded pigments.  

A rise in risk

Jeffrey Sonsino, O.D., chair of AOA's Contact Lens and Cornea Section (CLCS) who practices in Nashville, Tennessee, assessed the study by saying, "It points to the fact that we should not be prescribing some of the first-generation tinted lenses—the ones with the pigment on the surface. Most doctors are not prescribing them anymore. My guess is that the majority of patients who are still wearing that technology are purchasing their lenses illegally without a prescription."

Contact lenses sold to consumers without a prescription who are not under the care of a doctor of optometry present a genuine health hazard, says Dr. Sonsino.  

According to a 2015 AOA survey, 16% of Americans have worn vanity contact lenses that have no corrective powers. Of that number, 26% purchased those decorative lenses without a prescription. Without the guidance of a doctor of optometry, unwitting shoppers can easily gravitate to the cheapest options, which are often those first-generation lenses with the pigment on the surface that increase ocular inflammation.  

"Inflammation is when the cornea or the structures around it are put into physiologic stress. The result is that the body produces inflammation," says Dr. Sonsino. "Any time the eye is put into physiologic stress, the risk for some kind of adverse event goes up."  

The doctor habit

Circumventing the doctor of optometry by purchasing contact lenses online can lead to bad habits and poor preventive health. "Bad actors will send more than a year's supply of lenses to a patient, so the patient does not have a stimulus to see his or her doctor and get refreshed on all the proper techniques on keeping contact lenses safe," says Dr. Sonsino. Nearly all of the potential dangers of contact lenses—rom using outmoded technology to maintaining poor ocular hygiene—can be mitigated with an annual, comprehensive eye exam.  

AOA offers resources for decorative contact lens campaigns

October is a prime opportunity to reach the public about contact lens safety, which is why AOA has launched a public awareness campaign leading up to Halloween.

Representing a concerted approach to contact lens advocacy, the campaign reminds consumers about the dangers of illegal or improper contact lens use and stresses the importance of visiting their doctor of optometry before seeking decorative contact lenses. 

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