Meibomian glands also called tarsal glands are modified sebaceous ( oil glands) .A single row of Meibomian Glands (MG) is present in both the upper and lower lids slightly behind the eyelashes. There are around 35 -40 glands in the upper lid and 30-35 glands in the lower lid.
These glands secrete oil ( sebum ) which forms the uppermost layer of the tear film, protecting it
( water of the tears) from evaporation into the environment. If this oil is deficient or abnormal in quality, the tear film will not be stable on the ocular surface, leading to dryness or desiccation of the external eye surface. Peristent dryness can result in redness, itching, discharge, watering, transient blurring of vision, headache,and also discontinuity in the external layers ( cornea and conjunctiva).
The common causes of Meibomian Gland Dysfunction (MGD) are increased age, improper hygiene, excessive screen hours, contact lens wear, eye rubbing, smoking. MGD is twice as prevalent in diabetics as in the normal population.
Assessment of the Meibomian glands/ Meibography
Viewing of the under slit lamp and its duct assessment can be done by Meibomian gland expression by Q tip as a simple outpatient procedure. This gives an idea of the health and function of these glands.
Additionally Schirmers test ( Dry eye Strip test ) to evaluate water component of tear film and Tear Break up time (TBUT) to assess stability of tear film on ocular surface must be done .
Infrared Meibography ( with special equipment like LIPIVIEW/ SBM SISTEMI ) allow detailed observation of the silhouette of the shape, size and structure of the Meibomian glands. It involves white light transillumination of the everted lids from the skin aspect, with imaging based on black and white film, infrared film and a near Infrared charge coupled device ( CCD ) video camera.
Meibogaphy tests i.e MG evaluation are highly reproducible.
In patients with MGD, Meibography may show reduced number of glands. It also reveals shortening , kinking, twisting of the gland ducts. Meibography easily captures and depicts areas of complete gland drop out, if any i.e absent MG glands, hence allowing to judge disease severity.
Abnormality in meibomian glands, confirmed with the help of meibography tests points towards a diagnosis of Evaporative dry eye and Aqueous deficient dry eye is less likely. This helps us to plan out treatment systematically.
Management and Therapy
The patient is fully educated about the condition of his eyes. This is imperative for success of dry eye disease management.
Modification of the environmental factors such as avoiding exposure to dry condtions of low humidity which can increase tear instability and tear evaporation. It may help by creating a conducive environment for the eys with the help of humidifiers and moist chamber glasses.
Excessive use of digital devices decreases blink rate . This can be prevented by taking frequent breaks and blinking often consciously while using devices. Ergonomic corrections such as lowering the screen, allowing a downward gaze thereby allowing less ocular surface area to be exposed to the ambient air will help in reducing the dry eye condition.
Lid hygiene and warm compresses Appropriate lid hygiene is essential for lid conditions like blepharitis and meibomitis. Lid scrubs using a mild dilution of baby shampoo or a lid cleanser applied with a Q tip/ cotton swab can be used to clean lids. Patient compliance is very important for its benefits. Topical antibiotic ointments such as Azithromycin may help reduce bacterial load on lids in coexistent blepharitis. Warm compresses use heat to raise the temperature to soften / liquefy the thickened material obstructing the gland ducts, which then can be physically expressed out by physical force ( therapeutic expression by your treating doctor) Repeated warm compresses with either warm towels ( dry / wet ) placed externally has beneficial effect on both meibomian gland function and tear film in these patients. Certain devices like the Eyelid Mask / Warm Ocular massage device help in the management as it raises the lid temperature over a sustained period of time. These eye masks are microwavable , thus providing a convenient non messy way of heating the Meibomian glands.
Intense Pulsed light therapy ( IPT ) at Ojas A handheld laser emission device is used to deliver the appropriate light over a conducting lubricant jelly applied over skin after protecting your eyes with an eye shield. The parameters ( energy, interpulse interval, no of light pulses ) of this light will be adjusted by your surgeon according to your skin tone, severity of Meibomian glands dysfunction. The light pulses penetrate tissue and target the abnormal blood vessels which are the root cause of inflammation. The body’s own natural defense reaction then removes the abnormal vessels and heals the eyelid inflammation. The number of sessions may vary from 2-3 at an interval of 2-4 weeks depending on individual patient. Each session lasts for approximately 15 minutes. The treatemt is very gentle except for some sensation of warmth at times. Following this physical expression of the glands to remove ductal obstruction is performed by the physician thus allowing the glands to become functional. As compared to home therapy, series of IPL treatment with meibomian gland expression has shown a 90-95% improvement in signs and symptoms of dry eye refractory to other forms of treatment. IPT treatment also improves overall skin appearance.
Lubricants The use of preservative free lubricants helps replenish the depleted dry eye layer. Lipid containg lubricants are recommended for MGD , however not many options are available in India. High viscosity drops/ gels may be used for night time application. They promote tear retention at the ocular surface , protecting ocular surface against dessication.
Topical anti inflammatory medications like soft steroids may be prescribed for a short period to break the inflammatory cascades , which help to decrease the symptoms of grittiness, dryness.
Cyclosporine eyedrops ( Topical steroid sparing immunomodulatory agents): these eyedrops prevent inflammatory cell activation and production of inflammatory mediators. This has proven to be beneficial in mild, moderate and severe dry eyes. These are available as 0.05% and 0.1 % eyedrops to be used twice daily
Comments