Lipid Layer Thickness ??

The lipid layer thickness measurement and partial blink rate measurements were collected using the Lipiview Ocular Surface Interferometer (Tearscience), which captures, archives, manipulates, and stores digital images of specular (interferometric) observations of the tear film.19 The interferometry color
assessment is measured in interferometric color units (ICU), which can range from 0 to 240, with a precision of 1 ICU (1 nm).

Meibomian Gland Function ??

The quantity and quality of meibomian gland secretion were assessed using the Meibomian Gland Evaluator (Tearscience). This instrument, which has been usedin multiple randomized controlled clinical trials, applies standardized repeatable pressure over the meibomian glands to simulate the approximate forces of a deliberate blink; meibomian gland function is observed through a slitlamp. This instrument is used to assess the function of 15 glands on each lower eyelid.
The secretion for each gland is graded as follows: 0=no secretion, 1 = inspissated (toothpaste consistency), 2 = cloudy, and 3=clear/normal secretion; the maximum score is 45. Meibomian gland dysfunction was defined as a score of 18 or lower, which correlates to approximately 6 of the lower eyelid glands functioning at grade 3.

Meibomian Gland Structure??

Dynamic meibomian imaging (Lipiview II, Tearscience) was used to capture the meibomian gland structure, which was graded in a way similar to that recommended by Arita et al. The amount of atrophy in the lower eyelid was semiquantitatively assessed and graded (grade 0= no atrophy; grade 1 = 1% to 33% atrophy; grade 2 = 34% to 66% atrophy; grade 3 = more than 66% atrophy (eg, Arita grade 3=the lost area was more than two thirds of the total meibomian
gland area).