Table 2.

Average values and standard deviation (SD) of lipid layer thickness, non-invasive breakup time (NIBUT), tear meniscus height and bulbar redness of DED and healthy participants as measured after 30 min of each of the mask wear condition

	Healthy group	Dry eye group
Lipid layer thickness in nm (average, SD)
FFP2 mask	67.33 (± 15.23)	78.34 (± 20.11)
Surgical mask	66.24 (± 17.4)	84.56 (± 16.58)
No mask	64.79 (± 18.56)	81.02 (± 19.27)
NIBUT in seconds (average, SD)
FFP2 mask	16.01 (± 8.25)	9.9 (± 6.84)
Surgical mask	14.51 (± 7.81)	10.96 (± 9.67)
No mask	16.47 (± 7.96)	10.05 (± 6.56)
Tear meniscus height in mm (average, SD)
FFP2 mask	0.29 (± 0.07)	0.38 (± 0.31)
Surgical mask	0.29 (± 0.07)	0.36 (± 0.23)
No mask	0.28 (± 0.76)	0.35 (± 0.2)
Bulbar redness in arbitrary units (average, SD)
FFP2 mask	0.56 (± 0.22)	1.28 (± 0.51)
Surgical mask	0.56 (± 0.2)	1.38 (± 0.59)
No mask	0.66 (± 0.26)	1.34 (± 0.59)