Abstract
Purpose :
The aim of the study was to investigate changes in the profile of meibum lipids and concurrent alterations in meibomian gland (MG) function and morphology as a function of age and diet, in a normal adult population.
Methods :
185 subjects (109 females) within the age range of 25-66 years were examined specifically for MG function (meibum quality and gland expressibility), morphology (gland dropout) and dry eye disease signs, during a single clinical visit. Meibum samples were collected from both eyes, pooled and analysed using nano-electrospray ionization tandem mass spectrometry. A food frequency questionnaire (FFQ, Cancer Council Victoria, Australia), covering 74 food items, was administered to assess habitual eating habits over one year. Lipid data were normalized and log transformed prior to data analysis.
Results :
Meibum samples revealed the following lipid classes for the group as a whole: cholesterol esters (CEs, 60.7%), wax esters (WEs, 33.7%), (O-acyl)-omega-hydroxy fatty acids (OAHFAs, 3.3%), tri-acyl glycerides (TAGs, 2.2%) and ceramides (0.1%). Apart from CEs (nine subclasses), whose mean concentration reduced as age increased (p < 0.01), no other lipid class showed any statistically significant association with age or sex. A statistically significant reduction in the mean concentration of ten subclasses of OAHFAs, as well as TAGs and WE subtypes, was found with reduction in MG expressibility (p < 0.03). Five subclasses of OAHFAs also showed significant reduction in the mean concentration with increase in MG dropout (p < 0.02). Meibum quality and tear function variables did not show any association with MG lipids. From the FFQ, the distribution of the main food groups (log transformed) in the cohort diet (per day) was: carbohydrates (5.07 g), all fats (4.12 g), proteins (4.3 g), and fibre (2.96 g). There was a weak positive correlation between fiber and vitamin C intake with all meibum lipids classes (r<0.217, p=0.003 and r<0.209, p=0.005, respectively). None of the fatty acids was associated with any meibum lipid class (p>0.052).
Conclusions :
Cholesterol esters in meibum lipids tend to decrease with aging. OAHFAs in meibum lipids tend to be lower with decreased MG expressibility and increased gland dropout. The FFQ does not show any association between MG lipids and diet in this normal cohort without any ocular pathology.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.