More common than anterior blepharitis, posterior blepharitis describes inflammation of the posterior lid margin, and includes meibomian gland dysfunction (MGD), a condition that results from a dysfunction of the finger-like oil glands in the eyelids.
Although much literature uses the terms posterior blepharitis and MGD interchangeably, some have argued that MGD is a possible cause of posterior blepharitis. Other causes of posterior blepharitis are infections, allergies, and various systemic conditions, including acne rosacea.
Sometimes, meibum is not secreted, either because fibrotic tissue (periductal fibrosis) is blocking the flow of meibum, or because the meibum, that should flow like an oil, has thickened, and has the consistency of toothpaste. When this occurs it sometimes called obstructive meibomian gland dysfunction (o-MGD).
Meibomitis, or meibomianitis, is a subset of MGD and refers to inflammation of the glands.
Common Belief about Posterior Blepharitis and MGD
A commonly held belief is that obstructive MGD is due to thickened or abnormal secretions and that the best way to address this is with heat treatments. However, this is true only part of the time. Evidence suggests that that up to 75% of meibomian glands have periductal fibroses (vascularized fibrotic tissue) which obstructs the glands and can only be relieved with probing. These findings explain the lack of consistently effective results with conventional treatment (heat).
MGD is characterized by a disruption in the meibum producing or secreting system of the gland, and leads to evaporative dry eye. Many factors can disrupt the production and flow of meibum. These include, but are not limited to:
Age
Aqueous Tear Deficiency
Cold Climate
Conjunctivochalasis
Contact Lenses
Demodex Mites
Diet with a Poor Omega 3 to Omega 6 Ratio
Excessive Friction on Eye Lids During a Blink
Fibrotic Tissue that Blocks the Meibomian Glands (Periductal Fibrosis)
Food Sensitivities, that may be characterized by frequent breakouts and skin blemishes
Hashimoto’s Hypothyroidism
Hypothyroidism
Ice or Cold Packs Applied to the Eye Lids
Incomplete or Poor Blinking, not closing the eye completely with each blink
Infections: Bacterial, Viral or Fungal
Infrequent Blinking
Lid Massage
Micronutrient Deficiencies
Oral medications, such as isotretinoins,that reduce the amount of oil that is produced by the skin and is sometimes prescribed to individuals suffering from severe acne
Overuse of Lubricating Eye Drops
Poor Diet, Nutrition
Sex Hormones, too Little or too Much
Sluggish Metabolism
Smoking
Thick or Pasty Meibum
View all causes
References
The international workshop on meibomian gland dysfunction: report of the definition and classification subcommittee
Nelson JD, Shimazaki J, Benitez-del-Castillo JM, Craig JP, McCulley JP, Den S, Foulks GN.
Investigative Ophthalmology and Visual Science
2011 Mar 30;52(4):1930-7. doi: 10.1167/iovs.10-6997b. Print 2011 Mar.
PMID: 21450914
View the full report
The international workshop on meibomian gland dysfunction: report of the subcommittee on anatomy, physiology, and pathophysiology of the meibomian gland
Knop E, Knop N, Millar T, Obata H, Sullivan DA.
Investigative Ophthalmology and Visual Science
2011 Mar 30;52(4):1938-78. doi: 10.1167/iovs.10-6997c. Print 2011 Mar.
PMID:214509153
View the full report
The international workshop on meibomian gland dysfunction: report of the subcommittee on the epidemiology of, and associated risk factors for, MGD
Schaumberg DA, Nichols JJ, Papas EB, Tong L, Uchino M, Nichols KK.
Investigative Ophthalmology and Visual Science
2011 Mar 30;52(4):1994-2005. doi: 10.1167/iovs.10-6997e. Print 2011 Mar.
PMID: 21450917
View the full report