Modeling meibum secretion: Alternatives for obstructive Meibomian Gland Dysfunction (MGD)

Shangbang Luo; Gagik P Djotyan; Rohan Joshi; Tibor Juhasz; Donald J Brown; James V Jester

doi:10.1016/j.jtos.2023.11.005

Modeling meibum secretion: Alternatives for obstructive Meibomian Gland Dysfunction (MGD)

Ocul Surf. 2024 Jan:31:56-62. doi: 10.1016/j.jtos.2023.11.005. Epub 2023 Dec 1.

Authors

Shangbang Luo¹, Gagik P Djotyan², Rohan Joshi¹, Tibor Juhasz¹, Donald J Brown³, James V Jester⁴

Affiliations

¹ Department of Ophthalmology, University of California, Irvine, CA, USA; Department of Biomedical Engineering, University of California, Irvine, CA, USA.
² Institute for Particle & Nuclear Physics, Wigner Research Center, Budapest, Hungary.
³ Department of Ophthalmology, University of California, Irvine, CA, USA.
⁴ Department of Ophthalmology, University of California, Irvine, CA, USA; Department of Biomedical Engineering, University of California, Irvine, CA, USA. Electronic address: jjester@hs.uci.edu.

PMID: 38042297
DOI: 10.1016/j.jtos.2023.11.005

Abstract

Purpose: While changes in meibum quality are correlated with severity of meibomian gland dysfunction (MGD) and dry eye disease, little is known regarding the mechanics of meibum secretion. The purpose of this study was to develop a finite element model of meibum secretion and evaluate the effect of various factors that might impact meibum delivery to the ocular surface.

Methods: A finite element analysis in COMSOL 6.0 was used to simulate the flow of meibum within the gland's terminal excretory duct. Historical normal human meibum rheology data taken over the meibum melting range from fluid (35-40 °C) to solid (25-30 °C) were then used to calculate the minimum yield stress and plastic viscosity of meibum. The effects of meibum melting state, eyelid pressure and terminal duct diameter on meibum flow rates were then systematically investigated.

Results: The melting state of meibum from liquid to solid was associated with an increase in the minimum yield stress and plastic viscosity that caused an exponential decrease in meibum flow. Modeling also established that there was a linear correlation between meibum flow rate and eyelid pressure needed to express meibum and the 4th power of the terminal duct radius.

Conclusions: Our results suggest that changes in the melting state of meibum from fluid to solid, as well as changes in the radius of the terminal excretory duct and the force exerted by the eyelid can lead to dramatic decreases in the flow of meibum. Together these findings suggest alternative mechanisms for meibomian gland obstruction.

Keywords: Eyelid blink pressure; Finite element analysis; Flow rate; Meibomian gland dysfunction; Meibum; Modeling; Non-Newtonian; Orifice; Terminal duct; Viscosity.

MeSH terms

Dry Eye Syndromes*
Eyelid Diseases*
Humans
Meibomian Gland Dysfunction*
Meibomian Glands
Tears