Historically, the dry eye experienced by people with SS has been thought to be due to severe aqueous deficiency,
38 with little attention being paid to a possible role of evaporative dry eye. Meibomian gland dropout is the most common cause of evaporative dry eye.
38–40 Dysfunction of the meibomian gland is characterized by stenosis or obstruction of the gland orifices on the lid margins, inflammatory changes (redness, edema, telangiectasia), as well as quantitative and qualitative changes to the secreted meibum.
14 Stenosis of the gland orifices prevents meibum from being secreted from the glands. A build-up of meibum in the glands causes ductal dilation, cystic degeneration, loss of the meibocytes, and eventual gland atrophy.
14 A reduction in meibum volume and reduced quality of meibum secreted onto the ocular surface leads to alterations and thinning of the lipid layer and increased evaporation of the tear film.
14 Alteration to the lipid layer and LLT was evaluated in this study with the Tearscope. The Tearscope permitted viewing of the tear film lipid layer over the entire cornea, thus allowing evaluation of the lipid layer in an undisturbed state. Past studies have used the Tearscope to evaluate the lipid layer of potential and current contact lens wearers, to determine if the lipid layer would be suitable for lens wear, as well as to evaluate any changes that occur to the thickness and stability of the lipid layer during lens wear.
27,28 The studies found that a thick homogenous lipid layer, characterized as “amorphous,” tended to be the most stable.
28 In this study, the participants in the SS group presented with a significantly thinner lipid layer, with the majority of the lipid layers characterized as being an “open meshwork.” The positive correlation between LLT and NIBUT, with a thinner lipid layer being correlated positively with a shorter NITBUT, follows the trend previously reported by Maissa and Guillon.
29 The shorter NITBUT and thin LLT found in the SS group could be explained further by the reduced quality of secreted meibum in the SS group.