Examination of Human Meibum Collection and Extraction Techniques

Abstract

Purpose To compare various meibum collection methods and extraction techniques. Methods Sixty subjects, all successful contact lens wearers, were seen on two visits. Meibum was collected from the lower lid of the right eye with a glass microcapillary tube, and with a Dacron swab, cytology microbrush or spatula from the left eye. Extraction with 2:1 chloroform:methanol was done either immediately or after data collection was complete. Individual samples were divided into four equal aliquots for analysis of total lipids, cholesterol and inorganic phosphates via assay based techniques. Effects of collection method, extraction, and dry eye status were examined using repeated measures ANOVA and logistic regression. Results Total lipids showed significance of collection device (p<0.0001), but not for extraction technique (p=0.13) or dry eye status (p=0.97). Dacron swab collection was associated with more total lipid on average than each other collection device (p<0.0001). The cholesterol assay showed significance of collection device (p<0.0001) and extraction technique (p=0.0002), but not dry eye status (p=0.55). Spatula collection was associated with more cholesterol on average than each other collection device (p<0.0001). For inorganic phosphates, immediate extraction (p<0.0001), cytology microbrush collection (p<0.0001), and non-dry eye status (p=0.03) were associated with the greater likelihood of detection. Conclusions Dacron swab collection was associated with the highest average amount of total lipid detected, whereas spatula collection and immediate extraction was associated with the highest average amount of cholesterol detected. Cytology microbrush collection with immediate extraction on non-dry eye subjects was associated with the highest probability of detection of inorganic phosphates.

TFOS DEWS II Tear Film Report

“…Commercially available clinical devices (such as Yoshitomi’s meibomian gland pressure forceps, or Arita’s meibum collector) [120,282] ensure collection of ≤0.5 mg meibum per donor, thus allowing for multiple repetitions of experiments. The different meibum collection procedures (by glass microcapillary tube, Dacron swab, cytology micro brush, or spatula) and inherent intra- and inter-individual variability may contribute to variations in the amount and composition of the meibum samples [283–285]. …”

“…The opportunity was also taken to compare the effect of different collection techniques (microcapillary tube, Dacron swab, cytology micro-brush, spatulas) and extraction techniques (immediate and following storage) [283] on the lipid profiles obtained. A cytology micro-brush was the most efficient at recovering phospholipids (50%), followed by the spatula (40%), microcapillary tube (38%), and Dacron swab (23%), and the authors concluded that the choice of collection device and extraction method plays a significant role in the detection of meibum lipids, particularly phospholipids [283]. This study also showed that contact lens wearers not suffering from dry eye were more likely to have inorganic phosphates present in their meibum samples compared with samples from contact lens wearers who had dry eye [283].…”

“…A cytology micro-brush was the most efficient at recovering phospholipids (50%), followed by the spatula (40%), microcapillary tube (38%), and Dacron swab (23%), and the authors concluded that the choice of collection device and extraction method plays a significant role in the detection of meibum lipids, particularly phospholipids [283]. This study also showed that contact lens wearers not suffering from dry eye were more likely to have inorganic phosphates present in their meibum samples compared with samples from contact lens wearers who had dry eye [283]. Another study that compared lipid composition of meibum collected using cotton buds, the meibomian gland evaluator and meibomian gland forceps demonstrated that the use of the evaluator resulted in smaller polar lipid quantities than the cotton bud approach [282].…”

Surface properties and exponential stress relaxations of mammalian meibum films

“…From one side, a comparison of animal and human MGS films may help in finding a better animal model of the human ocular surface, as obvious ethical concerns limit the scope of the in vivo experiments with humans. Also identification of animal mimic of human meibum (hMGS) might be useful, as the acquisition of hMGS is currently a routine procedure (Haworth et al 2011), but its collection in substantial amounts for large-scale experiments is not a trivial task. This information could also be useful in guiding selection of treatments for domestic animals [who also suffer from DES ( ], from the arsenal available for humans.…”

Comparison of Collection Methods for the Measure of Human Meibum and Tear Film-Derived Lipids Using Mass Spectrometry

“…The different methods of lipid sampling from the tears and/or meibum include Schirmer's strips, glass microcapillary tubes, Dacron swabs, cytological microbrushes, and metallic spatulas. [25][26][27] The small volume of lipids collected and sample contamination are two issues that must be addressed with improved sampling techniques. Some of these methods may be capable of collecting more lipids than others, due to larger surface area or greater invasiveness, yet samples may be prone to contamination from surrounding tissues, debris, and cells.- 27 In contrast, other methods may be associated with lower levels of contamination, but a direct result of this may be lower collected volumes.…”