Abstract
Purpose: :
To examine the use of topical dexamethasone to improve the signs and symptoms of dry eye syndrome (DES) in a low humidity environment (LHE) chamber model.
Methods: :
12 patients with DES participated in this randomized, double-masked, placebo-controlled study. Enrollment criteria included OSDI score ≥31.25, corneal & conjunctival staining sum score ≥1 (Oxford scale) and ocular burning or stinging score ≥1 (0-4 scale). All patients were given a 1 week run-in with saline drops prior to exposure to the LHE for 90min for baseline measures (V1). They were then randomized into placebo(6) or dexamethasone(6) groups for tid dosing for 7 days. Patients were instructed to fill out "at-home" environmental symptom diary cards to gauge dry eye symptoms prior to each dose. After treatment, they returned for a repeat exposure to the LHE for comparative measures (V2). Corneal and conjunctival staining, TBUT, and "in-chamber" symptom diary cards were evaluated and analyzed pre and post-chamber exposure. Change from baseline was calculated by comparing V2 to V1.
Results: :
The LHE maintained temporally and spatially uniform temperature, air velocity and relative humidity (RH≤10%) for both visits and for the entire duration of the visit. Corneal & conjunctival staining sum scores for patients treated with dexamethasone were numerically lower compared to placebo (DEX: -0.63±1.36 vs. PLB: -0.25±1.18, n.s.). In addition, there was a smaller change in the reduction of TBUT in the dexamethasone group compared to the placebo group (DEX: 1.83±3.18 vs. PLB: 1.2±1.4, n.s). Dexamethasone patients also showed a marked and significant reduction in symptom exacerbation in the LHE in V2 versus V1 compared to placebo patients (DEX: -6.5±4.9 vs. PLB: 0.2±4.1, p<0.04). No significant ocular symptom improvement was noted in either group on "at home" environmental symptom diary cards.
Conclusions: :
The use of topical dexamethasone protected against the exacerbation of signs and symptoms of dry eye syndrome in the low humidity environment chamber model. The LHE is a well-controlled chamber facility capable of evaluating the efficacy of ocular therapeutics on dry eye. The LHE is a sensitive clinical model for testing ocular drug in a small patient sample.
Keywords: cornea: tears/tear film/dry eye • corticosteroids • keratitis