The lacrimal gland is located within the orbit above the eye. It is responsible for the continuous secretion of tears.
The lacrimal gland comprises of three kinds of cells; acinar, ductal and myoepithelial. The dominant cells in the gland are acinar, occupying about 80% of the space. Their task is to synthesize, store and secrete proteins. The ductal cells alter the main fluid produced by the acinar cells. They secrete water and electrolytes. Myoepithelial cells occupy the base of the acinar and ductal cell region. They work to push fluid out of the ducts and onto the ocular surface.
B and T cells, dendritic cells and bone marrow-derived monocytes also form part of the gland. Other cells include mast cells, plasma cells and macrophages. Most of the mononuclear cells in the lacrimal gland are the immunoglobulin A (IgA)-positive plasma cells.
Tears produced in the lacrimal gland flow through small ducts along the eyelid. They then drain from the eye through two tiny openings in the eyelids. The tears will exit through the nasolacrimal duct (tear) and into the nose.
The lacrimal gland produces tears in the form of electrolytes, water and protein. The tears help with the nourishment, cleansing and protection of the surface of the eye. They do this by lubricating and moisturizing the ocular surface.
Associated symptoms & disorders
Some of the conditions associated with the lacrimal gland are as follows:
- The immune system can interfere with the lacrimal gland giving rise to inflammation. Sjögren's syndrome can result due to the swelling. It is a systemic disorder where the white blood cells of the body attack tissue and organs that are otherwise healthy. This attack causes the immune system to attack the lacrimal gland leading to dry eyes.
- Sarcoidosis is another disorder that affects not only the lacrimal gland but other organs as well. It is a chronic systemic disorder whose origin remains unknown. Sarcoidosis involves a collection of abnormal cells called granulomas. It frequently leads to dry eye and dry mouth.
- Graft-versus-host disease (GVHD) results from a stem cell transplant on hematologic malignancies patients. It also affects the lacrimal gland leading to dry eye.
- Age is another factor that can negatively affect the lacrimal gland. As individuals age, the gland goes through alterations in its structure. For example, there may be an increase in mast cells and T and B cells.
- A malfunction of the lacrimal gland can directly lead to dry eye. Dry eye occurs when the lacrimal gland does not secrete enough volumes of tears. It can also result if the composition of the tears themselves is abnormal. With dry eye, the eye is vulnerable to infections and irritation from vapors and particles.
- Lacrimal gland tumors are very rare and arise from the gland. They can be epithelial or non-epithelial (the most common). They can also be benign or malignant.
Diagnosis of associated disorders
The eye care professional will conduct an eye examination which includes taking a medical history. The professional examines the eyelid, the surface of the eye and how an individual blinks. He/she may measure the thickness, amount and speed of producing the tears using the Schirmer's test.
The professional may check to confirm Sjögren's syndrome by measuring the amount of saliva in the mouth. A dye test is used to color the tears to monitor how quickly the tears dry up. Blood tests to check for antibodies and other blood markers may also be done.
Treatment of associated disorders
Because almost all the disorders associated with the lacrimal gland lead to dry eye, treatment for dry eye is highly recommended. It includes steroids to control inflammation, antibiotics to fight infection and artificial tears to replenish lost moisture. Particular eye drop medications help patients make more of their own tears. Certain drugs can help treat autoimmune disorders which ultimately improves the dryness.
Other treatment options include blocking tear ducts. The blockage causes the natural tears to stay in the eye longer. Small silicone or gel plugs are inserted into the tear ducts.
An implantable device has been developed that electrically stimulates the gland to secrete tears. It also stimulates the nerves which link the sensory neurons to the brain to produce tears.
Other remedies include warm compresses on the eye, massaging the eyelids and using certain eyelid cleaners.
Radiation or surgery may help to eliminate a lacrimal gland tumor.