Why do some people produce “pasty meibum?”
Why do some people produce “pasty meibum?” (A Root Cause of MGD that looks like strings of toothpaste or spaghetti - rather than thin, clear oil when expressed from these oil glands. This “clogs” the glands and creates obstruction.)
Some years ago, I was asked by a colleague about why some people produce “pasty meibum.” I wrote a long diatribe and when I saw a related question recently, I dug this answer up and thought I’d share.
Part 1:
Some of my answers would be somewhat modified today. (As most of you know, I’ve published on off label use of RF (radiofrequency) over Lipiflow and for addressing conjunctivochalasis, Zocuwipes over TTO related cleaning and Maxitears over other oils supplements - FD, consulting RF companies, part owner of the eyeThera company that makes the shields I use for RF expression and consultant to the Zocular company making the Zocuwipes).
My 4-part answer attempts to address that million-dollar question.
The Tear Science folks (initially headed by Drs. D. Korb, C. Blackie, et al - but now owned and operated by J&J) would include poor (partial) blinking in that answer, as that appears to be a major cause of stagnation of the oil producing eyelid glands (MGs). When stagnant oil becomes exposed to air, salts and the acidic breakdown products of bacteria and their oil-digesting lipases - it turns to soap and solidifies. Where normal MG (Meibomian Gland) oils are liquid at body temperatures, these harder oily complexes become wax-like and block the glands. The back-pressure appears to induce withering (or else they go on to produce styes). Of some interest is Dr. Korb’s finding that the temperature of the eyelids in patients with Meibomian (oil) Gland Dysfunction (MGD) is "colder" than those who don't have MGD. As far as I know, no one has been able to explain this phenomenon (though Dr. Korb points out that athletes have higher lid temperatures and appear less prone to this disease), but lower temperatures would also lead to solidification and blockage. Dr. Korb demonstrated to me the capillary attraction produced by the lids as they separate after a full blink. This engages the oil squeezed out by the action of the lids coming together with enough pressure to dispense micro-droplets onto the lid margin. Tiny vertical indentations in the lid margin assist in this backward and upward movement of oil - unless a waxy varnish obliterates these little "riverbeds" and occludes the openings. This is one reason I like to “debride” (scrape off) this waxy varnish as a part of my dry eye exam as it aids my diagnosis and may help in treatment of some with serviceable glands that are otherwise “dysfunctioning.”
Part 2 addresses other sources for tear oils and digs into what these oils are.