What Is a Meibomian Gland?
The meibomian glands are located in the tar-sus of the eyelid, are aligned perpendicular to the lid margin, and open at the lid margin. Its function is to secrete oil, lubricate the edge of the eyelid and prevent tears from flowing out of the conjunctival sac.
- Chinese name
- Meibomian glands
- Foreign name
- tarsal glands
- The meibomian glands are located in the tar-sus of the eyelid, are aligned perpendicular to the lid margin, and open at the lid margin. Its function is to secrete oil, lubricate the edge of the eyelid and prevent tears from flowing out of the conjunctival sac.
Meibomian gland , a common disease
- Dry eye
- 1. Also known as Keratoconj unctivitis sicca (KCS), first proposed more than 50 years ago. In 1996, the Dry Eye Research Group of the National Institute of Ophthalmology discussed dry eye and keratoconjunctivitis sicca as the same concept, both of which are called dry eye. The disease refers to a class of diseases that cause tear film instability and ocular surface damage caused by abnormalities in the amount or quality of tears, which cause eye discomfort, and are common ocular surface diseases. Clinically, those with ocular discomfort and no signs of ocular surface damage are called dry eye disease; those with both ocular discomfort and ocular surface damage are called dry eye disease. Keratoconjunctivitis is a change in ocular surface of Sjogren's syndrome, which is a dry eye disease. Dry eyes are more common in both eyes. Epidemiological and clinical examinations have found that the incidence is much higher than people think. Among them, the incidence of females is higher than that of men, and the incidence of those who often use computers and wear contact lenses is significantly higher than that of the control group.
- 2. Etiology and pathology
- (1) Environmental factors: Watching the computer screen or reading or driving at a close distance, the number of blinks is significantly reduced when focusing, which affects the uniform distribution of the tear film on the eye surface, which can induce or aggravate dry eyes. Air-conditioned environments, high temperatures, dry seasons, strong air currents, or electrostatic effects accelerate tear evaporation. Indoor air pollution (such as smoking and new decoration), changes in living environment, excessive fatigue, stress or lack of sleep can all affect the quality and quantity of tears, which can induce or aggravate dry eyes.
- (2) Ocular surface damage or drug-induced ocular surface changes: The cornea loses normal innervation after thermal burns or chemical injuries, resulting in a decrease in corneal sensitivity, causing a decrease in reflex tears or excessive tear evaporation. High temperature injury or chemical injury causes the loss or reduction of para-lacrimal gland secretion and scarring of lacrimal ducts, resulting in insufficient secretion of watery tears. Trauma accompanied by ocular inflammatory reactions or preservatives in local medicines destroys conjunctival goblet cells, resulting in a lack of mucin secretion and decreased tear film stability. Some systemic medications (antihypertensive drugs, antihistamines, anticholinergics, diuretics, antidepressants, etc.) can affect tear secretion.
- (3) Defective or incomplete closure of the eyelid margin: Traumatic, congenital eyelid defect or facial nerve paralysis caused by incomplete eyelid closure, abnormal eye movements, causing tears to be unevenly distributed and timely updated, causing tears to evaporate too quickly.
- (4) Meibomian dysfunction or meibomian gland obstruction: trauma or surgery damages the meibomian gland, loss of meibomian gland function, resulting in lack of tear lipid secretion. The meibomian glands secrete abnormally, which disrupts the balance between the polar lipid phase and the non-polar lipid phase in the lipid layer, and the evaporation of ocular surface water accelerates.
- (5) Limbal stem cell dysfunction: Some inner eyes (glaucoma, cataract) and ocular surface surgery (sacral surgery), ocular surface chemical injuries, congenital absence of iris, etc., cause damage to the limbal tissue structure and physiological functions, resulting in The corneal epithelium replacement is disturbed, which affects the stability of the tear film.
- (6) Connective tissue lesions: such as rheumatoid arthritis, lupus erythematosus, Sjögren's syndrome, etc., the lacrimal gland is infiltrated by a large number of lymphocytes, and secreted tears are reduced.
- (7) Sex hormone dysregulation: Sex hormones, especially androgens, can regulate the body and local immune functions, and regulate the morphology, development, differentiation and secretory functions of the lacrimal gland and meibomian gland. And menopause, aging, autoimmune diseases, androgen drugs can cause androgen deficiency and dry eyes.