Purpose:
The purpose of this study was to examine changes in total tear film thickness and tear film thinning in patients enrolled in one site of a multi–center, parallel group, double–masked, randomized, placebo–controlled study of multiple ocular instillations of diquafosol tetrasodium ophthalmic solution 2% (INS–365) in subjects with dry eye disease using an interferometry technique called wavelength–dependent fringes (WDF). An increase in tear film thickness would be expected given the mechanism of action for diquofosol.
Methods:
Tear film thickness (in microns) and tear film thinning rates were measured in 22 patients at a single site. Seven minutes following instillation of study drops, continuous interferometry readings were recorded for two minutes while the patient blinked every 4 seconds in accordance with a metronome. Approximately 20 reflection spectra time points were averaged per patient sitting. Interferometry measurements were taken at baseline and at week–6 following treatment.
Results:
At baseline (B), no statistically significant difference was found in total tear film thickness between the placebo (P, n = 11) and treatment (Tx, n = 11) groups (p = 0.42). A significant difference in thickness (p = 0.02) was seen between baseline and week–6 (E) in the treatment group at 1 second following the blink (baseline: 3.493µm vs. week–6: 4.017µm). In addition, the treatment arm demonstrated a thicker tear film than the placebo group (Figure 1) across the 4–second inter–blink interval. The measured thickness of the tear film is consistent with tear film thickness measurements in normal patients (3–4µm).
Conclusions:
Multiple ocular instillations of diquafosol tetrasodium ophthalmic solution 2% (INS–365) over a six–week period result in a thicker tear film in subjects with dry eye disease, although thinning rates appear similar between groups and there is considerable variability between subjects.
Keywords: cornea: tears/tear film/dry eye • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials