Abstract
Purpose:
Dry eye syndrome has been reported to exhibit seasonal fluctuations, possibly due to increased evaporation in winter months.[1] To date, no empirical studies have been performed to compare symptoms in and out of season within the same cohort of patients. We performed a meta-analysis of dry eye study data to evaluate seasonal differences in diary-reported symptoms.<br /> <br /> <br /> [1] McCulley JP, Uchiyama E, Aronowicz JD, Butovich IA. Impact of evaporation on aqueous tear loss.<br /> Trans Am Ophthalmol Soc. 2006;104:121-8.
Methods:
Diary-reported symptom scores from 10 clinical trials in dry eye, completed over a 6-year period, were compiled in a longitudinal database. Data were selected from subjects treated with placebo in pre-trial run-in periods for the purposes of study eligibility. A subset of 270 subjects who had participated in at least one summer season study (April-September enrollment) and one winter season study (October-March enrollment) were identified and included in the analysis. Differences in diary-recorded ocular discomfort and dryness symptoms (graded using the Ora CalibraTM 4-Symptom Scale) were compared between winter and summer seasons to identify any seasonal differences in symptom severity.
Results:
There was a significant seasonal difference observed for diary-reported ocular discomfort symptoms (summer - winter, -0.119 ± 0.916 (p=0.034), with patients experiencing higher levels of symptoms during the winter season. Patients also reported higher dryness levels during the winter season, although this difference did not reach statistical significance (p=0.140).
Conclusions:
Seasonal differences in patient-reported symptoms were observed in this analysis, with elevated ocular discomfort reported during the winter season. In the context of clinical trials, seasonal variations in symptoms may be a confounding factor, and best efforts should be made to complete trials within a given season to minimize this variability.