Corneal sensitivity and symptoms increase diurnally in symptomatic lens users, no matter how long they wear their lenses, a recent study reported. Still, tear meniscus height remain unaffected, the add.

The study included 26 symptomatic and 25 asymptomatic contact lens wearers and 15 asymptomatic non-lens users. A team measured cooling thresholds, symptoms and tear meniscus height within one hour of awakening (baseline) and three, six and nine hours later on day one and at baseline and nine hours later on days two and three.

The researchers found that cooling thresholds for the symptomatic group were lower and decreased over day one and after eight hours of contact lens wear on day two and were paralleled by increased symptoms—they noted minimal variations in the asymptomatic and control groups. They added that tear meniscus height varied little over time and was lower in the symptomatic group but the difference was not statistically significant.

“These results reveal the essential role of neurosensory abnormalities in contact lens discomfort and suggest involvement of a central mechanism in the diurnally increased symptoms of these patients,” the study authors concluded in their paper.