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Studies show asymptomatic infiltrates often unaccounted for
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NEW YORK – A clinician reported here at the Global Contact Lens Forum, held prior to Vision Expo East, that her research has shown the incidence of corneal infiltrates to be 26% in silicone hydrogel extended wear, much higher than indicated in FDA trials.
Loretta Szczotka-Flynn, OD, PhD, FAAO, of Case Western Reserve University, said her interest in the topic began when a patient with a history of multiple corneal infiltrates who was wearing silicone hydrogels came to her with contact lens peripheral ulcers (CLPUs).
“They went away when I put her in a daily disposable lens,” Szczotka-Flynn said.
She conducted a meta-analysis of studies that showed the incidence of infiltrates was higher in silicone hydrogel lenses.
“This was discouraging, because we were excited to see silicone hydrogels enter the market,” she said, “and the FDA studies showed the incidence rates were low.”
Szczotka-Flynn said she watched patients closely and frequently over a 1-year time period and documented an incidence rate of 26% with silicone hydrogel extended wear.
“Why did we get such a high number?” she asked. “We saw the patients frequently and were able to detect asymptomatic events. A lot of the CLPUs were asymptomatic.
“We re-did the study in daily wear ... and we documented a 7% incidence rate, with only 2% symptomatic. The asymptomatic occurrences are driving the incidence rate.”
Szczotka-Flynn said her early research showed that one of the biggest risk factors for infiltrates in extended wear was lens bioburden. Subsequent studies have found that bacteria on the lens increased risk 800%, smoking increased risk 400%, and bacteria cultured off the lid increased risk 400%. Mucin balls have been shown to decrease risk 84%. Corneal staining was not a risk factor.
A later study showed that mucin balls were not as protective as the previous study indicated, Szczotka-Flynn said.
“Patients who formed mucin balls had an infiltrate rate of 18%, and those who did not form mucin balls had an infiltrate rate of only 5%, so we found the opposite effect,” she said. “We now believe that creating mucin balls early is risky and increases the risk of infiltrate by over 400%.
“If you’re putting a patient in extended wear lenses for the first time, look for the mucin balls,” she continued, “and, if you’re seeing them now, realize they’re risky, and you should take the patient out of extended wear.”
Szczotka-Flynn concluded: “The incidence of corneal infiltrative events (CIEs) during extended wear is 20% to 25%. We still believe silicone hydrogels have an increased risk of CIEs by two times. Bacterial bioburden plays a key role. Early mucin ball formation increases CIE during extended wear 20% to 25%.” – by Nancy Hemphill, ELS, FAAO
Reference:
Szczotka-Flynn L. Evidence-based eye care and clinical practice: A review of research in clinical practice. Presented at: Vision Expo East, New York. March 30-April 2, 2017.
Disclosures: Szczotka-Flynn reported she is a consultant for Alcon and Johnson & Johnson Vision Care.