This randomized controlled study was performed to compare the outcome of dry eye treatment between two severity assessment techniques: corneal epithelial thickness (CET) measurement by spectral domain optical coherence tomography (OCT) and clinical eye examination.

The study involved >18-year-old patients who had been diagnosed with dry eye by the Tear Film & Ocular Surface Society’s Dry Eye Workshop II criteria. Ninety-two patients were randomized in a 1:1 ratio to the OCT group, in which the severity of dry eye was evaluated with spectral domain OCT, and the control group, in which the severity was evaluated by clinical eye examination. The severity of dry eye was categorized as either mild to moderate or severe. Both groups received 3 months of treatment according to their severity.

The primary outcome was the mean change in the tear breakup time (TBUT) at 1 and 3 months compared with baseline. The secondary outcomes were the mean change in the 5-Item Dry Eye Questionnaire (DEQ-5) score and the fluorescein stain grade at 1 and 3 months compared with baseline.

In the OCT group, 28 patients had mild to moderate dry eye and 18 had severe dry eye. In the control group, 31 patients had mild to moderate dry eye and 15 had severe dry eye. Seven patients were lost to follow-up. At 3 months, the mean TBUT was 0.21 seconds higher in the OCT than the control than control group, but without statistical significance (P = .487). The mean DEQ-5 score was 0.10 points higher in the OCT than control group, but also without statistical significance (P = .669). The mean fluorescein stain grade was 0.09 points lower in the OCT than the control than control group, again without statistical significance (P = .245). The agreement between OCT and clinical assessment for diagnosis of severe dry eye was 88.04% (Kappa coefficient, 0.7384), showing good agreement; however, there was no correlation between the TBUT and CET variance at baseline  (Pearson’s  correlation, 0.0344).