Assessing Meibomian Gland Dysfunction at Different Ages: The Role of Tear-film Lipid Layer Thickness

26 Oct, 20

Introduction

Meibomian gland dysfunction (MGD) with a growing prevalence is considered as a new public health problem. The diagnosis of the disease is mostly based on invasive techniques. Meibomian lipids have a critical role in stabilising tear-film and preventing tear evaporation. Lipid deficiency due to MGD results in thinning of the lipid layer and increases the instability of the tear-film. The evaluation of lipid layer thickness (LLT) may thus have a valuable role in the diagnosis and classification of MGD.

Aim

To evaluate the correlations between LLT and morphology and function of the MG in patients diagnosed with MGD in different age groups.

Patient Profile

Patients with obstructive MGD and attending the outpatient department of the Eye Hospital of Wenzhou Medical University, Hangzhou, China
Based on age, patients were divided into three groups as follows:
- Young: Ages 20–39 years
- Middle-aged: Ages 40–59 years
- Older-aged: ≥60 years

Methods

Study Design

Prospective, cross-sectional study

Assessments

Subjective symptoms were assessed using the Ocular Surface Disease Index (OSDI) questionnaire
The following were evaluated for all patients:
- LLT
- Tear meniscus height (TMH)
- Noninvasive tear film break-up time (NI-BUT) measurement
- Invasive TBUT (ITBUT)
- Corneal fluoresceinstaining (CFS) score
- Eyelid margin abnormalities
- Schirmer I test
- MG function and morphology

Results

Two hundred and nine patients (209 eyes) were included in this study. The mean age of the study population was 49.68 years.
The median LLT of all patient was 57 nm (IQR, 36.5 nm), and the LLT values differed significantly among the young group (median, 51 nm; IQR, 23.5 nm), middle-aged group (median, 59.5 nm; IQR 46.5 nm) and older group (median, 62 nm; IQR, 42.5 nm) (P = 0.033, Kruskal-Wallis test).
As per regression analyses adjusted for confounding factors gender and MG loss, the LLT correlated positively with age (? = 5.539, P = 0.001).
LLT correlated negatively with MG dropout in the all (r = − 0.527, P <0.001), young (r = − 0.536, P < 0.001), middle-aged (r = − 0.576, P < 0.001), and older (r = − 0.501, P < 0.001) groups.
LLT also correlated positively with the MG expressibility in the all (r = 0.202, P = 0.003), middle-aged (r = 0.280, P = 0.044) and older (r = 0.452, p < 0.001) groups, but was not statistical significant in the young group (r = 0.007, P = 0.949).

Conclusions

The thickness of LLT increased with age and correlated significantly with both MG secretion and morphology in middle-aged and older patients with obstructive MGD.
LLT measurement is a valuable screening tool for detecting obstructive MGD. Impact of age should be accounted for when interpreting the LLT value.

BMC Ophthalmol. Oct 6, 2020 (Published Online);20(1):394. doi: 10.1186/s12886-020-01667-8.