MGD is an extremely common chronic disorder of the eyelids with a high rate of misdiagnosis and inadequate attention by clinicians. MGD is closely related to dry eye and is a major cause of evaporative dry eye (LTD), while MGD is often associated with the ocular surface disease ATD, which exhibits common signs and symptoms. Treatment of MGD Since the etiology of MGD has not been fully elucidated, treatment options are mainly symptomatic, with inexact efficacy and poor long-term results, so people continue to explore and research better treatment options relentlessly. In recent years, there have been new advances in physical therapy, immunomodulation, and environmental regulation, and new discoveries in the mechanism of antibiotic therapy. I. Basic treatment 1. Eyelid hygiene and hot compresses Eyelid hygiene and hot compresses are the most commonly used treatment methods. Hot compresses on the eyelids help to increase local blood flow to the eyelids, melt the lipids of the lid glands, and contribute to the stability and uniformity of the lipid layer of the tear film, which can relieve irritation in patients with MGD. Lid scrubbing removes lid margin debris and cured secretions that block the lid duct openings, reducing external lid gland opening blockage and is also a common treatment for staphylococcal and seborrheic blepharitis.MGD is a chronic condition that requires long-term adherence to lid hygiene and hot compresses. In the past, physicians have often recommended that patients use baby shampoo to clean their eyelids, but it has been suggested that, logically, baby shampoo has a saponifying effect that can exacerbate inflammation and damage to the tear film from free fatty acids and is not approved for use on the face, so it is not recommended for widespread clinical use. 2. Blepharoplasty Blepharoplasty is simple and convenient, and is a common physical therapy performed by patients at home. It was first proposed by Thygeson and has been used for more than half a century. It is performed by using the front of the index finger to make a rotating motion at the lid margin, or by scraping the lid margin with the index finger from the inner canthus toward the outer canthus. It is usually performed after a hot compress on the eyelid. The principle is that by raising the temperature and increasing the pressure the thickened secretions in the lid gland are drained, thus eliminating the obstruction of the lid gland and causing the patient to have less symptoms. solomon JD et al. found that hot compresses and massage of the lid gland resulted in changes in the physical properties of the cornea, causing transient blurred vision. Therefore, it is recommended that patients be supervised by a family member when performing blepharoplasty at home. 3. Blepharoplasty Blepharoplasty is usually performed in the hospital and requires the use of a surface anesthetic. After the conjunctival sac is surface anesthetized, the left hand flips the eyelid and the thumb is placed on the skin surface of the lid to apply pressure to the lid, while the right hand holds a glass rod or cotton swab on the conjunctival surface of the lid and squeezes the lid against the fornix towards the lid margin to unblock the opening of the lid gland and squeeze out the lid gland secretions. In China, studies have shown that the majority of patients with obstructive MGD treated with blepharoplasty have a clear opening to the lid gland and significant relief of ocular discomfort. Blepharoplasty is effective in relieving the blockage of the lid gland, but it is performed under surface anesthesia and can cause significant pain, and some patients develop acute conjunctivitis and subconjunctival hemorrhage after treatment. Second, instrument-assisted physical therapy 1, eye heater Recently reported eye heaters have been marketed, including disposable heated eye masks trade name Eye Warmer, a product of Tokyo Kao, water vapor heater trade name warm moist air device, etc.. Disposable heating eye mask processed into the form of eye mask, the principle of the iron contained in the exposure to oxygen-containing water environment oxidation to iron hydroxide, and generate heat and water vapor, so as to achieve the effect of fumigation, hot compress; similarly, water vapor heater is processed with insulated steel plate with thermostat and rubber pad into the shape of goggles, the bottom of the goggles can hold 200ml of water, by controlling the temperature of the water to produce a continuous Matsumoto Y and other experts conducted a prospective controlled study by means of water vapor heater and towel hot compress on the eyelids and found that both groups improved the ocular surface symptoms, the experimental group caused a significant increase in the ocular surface temperature within 10 minutes, increased the thickness of the lipid layer of the tear film and prolonged the tear film rupture time BUT. In contrast, there was no change in the control group BUT, and the increase in the thickness of the lipid layer of the tear film after 2 weeks was less than that of the experimental group. The superiority of the water vapor heater was illustrated. The new device, although effective, still has significant drawbacks in application. For example, there is heat loss when heat energy is transferred from the skin surface of the eyelid to the conjunctival surface of the lid, and the relatively insulating nature of the eyelid tissue results in inefficient heat energy transfer. 2. The novel thermodynamic treatment device is the first device to deliver heat directly from the inner surface of the eyelid while applying pressure to the lid gland and avoiding pressure on the eyeball, making it more effective than traditional methods. The device consists of an eyelid heater and an eye cup. The eyelid heater is shaped like an eye mold, and its concave side contains insulating material that adheres to the sclera, preventing heat transfer to the cornea and ocular surface. Its convex surface is embedded with a precision heater and multiple temperature sensors that heat all the lid glands of the upper and lower eyelids at once in 12 minutes through the inner surface of the lid glands. The cup contains an expandable air sac that is fixed to the surface of the eyelid while the scleral lens is built into the eye, squeezing the lid gland in the direction of the lid gland opening so that it heats the lid gland while promoting lid gland secretion.In 2010, Donald R et al. reported that the LipiFlow thermokinetic device Tear Science produced for the treatment of MGD and that the device was clinical evaluation of the device. The LipiFlow is already in use in Europe and is currently being approved by the US Food and Drug Administration. 3. Needle lancing of the lid gland In 2010, MaskinSL was the first to use a physical method to access the gland to unblock it. Twenty-five patients with O-MGD were treated with lid acupuncture for obstructive lid gland dysfunction, and 16% of patients were treated with other dry eye treatments, including lacrimal punctal embolization. The results showed that 96% of patients had immediate relief of symptoms, 100% of patients had relief of symptoms after 4 treatments for 4 weeks, and 80% of patients required only one lid gland exploration to achieve results. After 11 months of follow-up, no adverse effects were seen. The ability to safely access the lid gland and achieve good results is important for exploring the pathophysiology and pathogenesis of the lid gland. When physical therapy is not completely effective, local and systemic antibiotic therapy is required. The main drugs are tetracyclines, doxycycline, and minocycline. The tetracycline antibiotics, including tetracycline, doxycycline, and minocycline, can reduce the inflammatory response and reduce free fatty acids and glycerides and other harmful components in the secretions of the lid gland. Studies have also found that tetracyclines and their analogs have anti-MMP effects, inhibit MMPs, cytokines, and therefore affect inflammation, immune regulation, cell proliferation, and angiogenesis. The use of tetracyclines in the treatment of ophthalmic diseases is in its infancy. 2. macrolides In the same way as tetracyclines, macrolides also have antibacterial and anti-MMP effects. In a 2008 study, patients with posterior blepharitis treated with a macrolide, azithromycin 1% eye drops, showed significant improvement in the quality of lid secretions and marked relief of eyelid redness. 2010, Gary N et al. By implementing a 1% concentration of azithromycin eye drops manufactured by Inspire Pharmaceuticals, Dartmouth, New Caledonia, and collecting lid gland lipids for analysis after 4 weeks, the phase transition temperature phase transition temperature of lid gland lipids was found to be altered. Low phase transition temperature is one of the indicators of enhanced mobility of the lid gland lipids. Therefore, this study confirms that azithromycin can improve the symptoms of the lid gland by improving the lipid conformation of the lid gland, increasing the mobility of the lid gland, and relieving the blockage of the glandular ducts. 3. N-acetylcysteine NAC NAC is an acetylated derivative of natural L-cysteine, a mucolytic antioxidant that affects a variety of inflammatory metabolic pathways and regulates intracellular redox status, and also has anti-keratinocyte proliferative effects. Due to its mucolytic and anticollagenolytic properties, NAC has been successfully used in ophthalmology for the clinical treatment of corneal diseases such as keratoconjunctival desiccation syndrome, filiform keratitis, etc. A prospective controlled study by Akyol-Salman I et al. using NAC for MGD and preservative-free artificial tears only found that the mean Schirmer’s score in the NAC-treated group increased to a greater extent than in the control group. The NAC-treated group had better mean Schirmer scores than the control group and significantly improved the symptoms of ocular pruritus. Immunomodulation The treatment of dry eyes with cyclosporine A has been agreed upon, but the treatment of MGD is still being explored. in 2004, an attempt was made to treat inflammatory MGD and MGD that did not respond to other medications with glucocorticoids, 0.05% cyclosporine A eye drops, and encouraging results were achieved. Cyclosporine A interrupts the immune-mediated process by binding to specific nuclear proteins that initiate T-cell activation and inhibiting T-cell production of inflammatory cytokines such as IL-2, while glucocorticoids inhibit the production of inflammatory cytokines and chemokines, reduce the synthesis of lipid mediators such as MMP (e.g. prostaglandins), decrease the expression of cell adhesion molecules, and stimulate lymphocyte apoptosis. SN found that MGD patients treated with cyclosporine showed improvement in symptoms and objective indicators, time to tear film rupture, etc. Therefore, cyclosporine can be applied to reduce inflammation when the lid gland is decongested by hygienic care and physical therapy. Topical application of corticosteroids can be effective in treating dry eyes and suppressing the inflammatory response, but given their side effects, they can only be used for a short period of time. V. Androgen therapy The lid gland has androgen receptors, and other sebaceous glands throughout the body are not sensitive to androgens. Antiandrogen therapy has been shown to improve the secretory function of the lid gland. In patients with abnormal sex hormone levels, androgens can improve the structure of the lid gland and improve the quality of the lipid layer. However, systemic application of androgens can have significant side effects, and topical androgens are being evaluated as a possible treatment for MGD. VI. Nutritional Support The use of dietary supplements for MGD is now the newest area of research in ophthalmology. one of the symptoms in MGD patients, namely altered TFLL, and supplementation of fatty acid intake could theoretically improve the nature of the lid gland secretions. Omega-3 fatty acids and omega-6 essential fatty acid supplements have been used as over-the-counter medications to help MGD patients improve their symptoms. Omega-3 fatty acids are essential nutrients for human growth and development. Omega-3 fatty acids and omega-6 essential fatty acids compete to bind the same enzyme, which is ultimately catalyzed by the enzymes into the anti-inflammatory prostaglandins PGE 3, leukotrienes and PGE2, and leukotrienes, respectively. BY Marian S. Macsai MD demonstrated in a prospective randomized placebo-controlled trial that the administration of w-3 dietary supplements reduced erythrocyte and plasma levels of w-3 and w-6; reduced saturated fatty acid content in lipids secreted by the blepharic glands, and improved overall OSDI scores, TBUT, and lipid quality. The use of lipid-containing artificial tears such as phospholipids, saturated and unsaturated fatty acids, and triglycerides has also been attempted to treat MGD patients with satisfactory results. In 2003, Eiki Goto et al. analyzed the kinetics of tear punctal occlusion (PO) in 17 patients with tear-deficient dry eye before and after PO treatment and found that PO significantly shortened lipid propagation time and improved lipid layer uniformity and thickness, suggesting that the performance of the lipid film also depends on the amount of tear fluid. These studies provide new insights into the interactions between lipid membranes and the tear aqueous layer. VIII. Environmental modulation Exposure to conditions of low humidity such as deserts, air-conditioned rooms, and airplane cabins with high temperatures increases the rate of tear evaporation, and avoiding these environments can reduce dry eye symptoms and decrease the use of artificial tears. Aqueous/mucous egg analogs are the most common artificial tears used to treat MGD, improving patient symptoms and promoting uniform distribution of lid gland lipids across the ocular surface. In summary MGD is a common clinical condition that is associated with changes in the composition and function of the lipids produced by the lid gland. Traditional approaches are only symptomatic, and in recent years, more and more new therapies have begun to explore the pathogenic mechanisms with some success.