Review of Literature on Intraductal Meibomian Gland Probing with Insights from the Inventor and Developer: Fundamental Concepts and Misconceptions

Abstract

Obstructive Meibomian gland dysfunction (MGD) affects millions of patients around the world. Its effective treatment with intraductal meibomian gland probing (MGP), was first reported in 2010. Since then, MGP has provided relief to thousands of patients globally suffering with refractory MGD. The purpose of Meibomian gland probing is restoring the integrity of the gland's central duct by entering the gland through the natural orifice, releasing fixed obstruction thought to be periductal fibrosis, thereby establishing and/or confirming the patency of the duct, and concurrently equilibrating intraductal pressure as well as promoting gland functionality with meibum production. There may or may not be immediate secretion of meibum upon successful restoration of ductal integrity depending on the gland's state of function and degree of atrophy. One double-blind placebo-controlled study has been conducted and, with the accumulated evidence of over 12 other peer reviewed articles in the scientific literature, overwhelmingly indicates that MGP is a safe and effective treatment for the MGD patient refractory to prior standard care and as a first-line treatment. This paper describes relevant fundamental concepts, dispels commonly held misconceptions, and provides an objective review of the current understanding and effectiveness of MGP for the treatment of obstructive MGD. Our analysis will better equip clinicians to draw informed conclusions about both subjective and objective findings reported in MGP studies and researchers to design future robust studies that provide meaningful results.

Keywords: MGD; MGP clinical trial; MGP studies; dry eye; meibomian gland dysfunction; obstructive MGD.

Figure 1

(1a and b) Performing supraorbital and infraorbital nerve block using JBP 33 gauge 4 mm long nanoneedles. (2a and b) Jojoba anesthetic ointment consisting of 8% lidocaine and 25% jojoba is taken from a refrigerated jar and applied to the lid margin for 10 minutes. This may be repeated. (3) The probing set-up at the slit lamp with an assistant to steady the patient for good visualization. (4) View through the slit lamp microscope of probing upper (a) and lower (b) lid Meibomian glands. (5) Meibography guided probing using the Mediworks S390L WDR FireFly Digital Slit Lamp from Eyefficient (Aurora, Ohio), demonstrating a 4 mm probe within the central duct (a), a sterile MicroTube Stent within the central duct for retrieval of meibum (b) and the retrieved meibum inside the MicroTube removed from within the gland (c). Reproduced from Maskin SL, Alluri S. Meibography guided intraductal meibomian gland probing using real-time infrared video feed. Br J Ophthalmol. 2020;104(12):1676; with permission from BMJ Publishing Group Ltd. (6) An alternative approach to obtaining a virgin sample of meibum by allowing the meibum to travel through the MicroTube Stent for collection and analysis. Arrow shows a drop of meibum at the distal end of the MicroTube Stent.

Figure 2

Probe findings form of a patient.

Figure 3

Confocal microscopy image of Meibomian gland distal duct showing disruption of the normally well demarcated external duct wall by fibrovascular tissue invasion. A prominent blood vessel is seen inside the oval. The disruption of the duct wall is indicated by the solid arrow showing a “step off”. This gland had not been probed. (Courtesy of SLM.).