The cause of dry eyes is the tear film that coats the cornea being disturbed for many reasons or abnormalities that occur in the layers of tears can cause dry eyes, irritation, and itching. Normally, there are 3 layers of tears on the cornea: 
 

• Lipid Layer 

The lipid layer is the outermost layer of the tear film and helps prevent tears from evaporating too quickly. The lipid layer is produced by sebaceous glands called Meibomian Glans. 
 

• Aqueous Layer

The watery fluid layer, or simply called the aqueous layer, is the layer between the Lipid Layer and the Mucin Layer. The aqueous layer is the main component of tears. It protects the eye by producing tears to wash away foreign objects that enter the eye. The aqueous layer is produced by the lacrimal glands.
 

• Mucin Layer

The mucus layer is the innermost layer of the tear film and is responsible for keeping the cornea moist. The mucus layer is made up of cells called goblet cells that are found in the conjunctiva and cornea. 

The causes of dry eyes are diverse and can be divided into two main causes:
 

1. Less than normal tear production process

Dry eye can occur when the tear production process is insufficient. Medically, it is called Keratoconjunctivitis Sicca. โปรโมชั่น ufabet Causes of less than normal tear production include:
 

• Elderly people or people over 50 years of age 
• Certain diseases impair the production of sugar , such as Sögren’s disease, allergic conjunctivitis, rheumatoid arthritis, autoimmune diseases, GVHD, sarcoidosis, thyroid disease, or vitamin A deficiency. 
• Use of certain medications , such as antihistamines, vasoconstrictors, hormone replacement therapy, antidepressants, high blood pressure medications, and birth control pills. 
• Macular degeneration is caused by contact lens wear or nerve damage. In addition, laser surgery can cause frequent dry eyes, but it is only temporary.
   

2. Faster than normal evaporation of tears

Dry eyes and eye irritation may be caused by faster than normal evaporation of tears, which is caused by a blockage of the outermost layer of the tear film, also known as the lipid layer. Blockage of the tear film layer is common in patients with rosacea or other skin diseases, as well as other causes that cause faster than normal evaporation of tears, including:
 

• Blepharitis is an inflammation caused by a malfunction of the meibomian glands. Meibomian glands are the glands that produce the outer layer of tears, preventing the tears from evaporating too quickly. 
• Blinking less is caused by certain diseases, such as Parkinson’s disease, or by doing certain activities, such as driving, reading, or staring at a computer screen while working.
• Eyelid abnormalities , such as ectropion or entropion, can cause irritation of the cornea. 
• Allergic eye disease 
• Preservatives in eye drops or artificial tears Preservatives in artificial tears can cause tears to evaporate more quickly than normal and may cause irritation in some users.
• Wind, smoke and dry air areas
   

Symptoms of dry eye condition

Usually, when dry eyes occur, symptoms occur in both eyes at the same time, with the following symptoms: 
 

• Eye irritation, burning, itching , or a feeling like there is dust in the eye. 
• There is sticky mucus around the eyes.
• conjunctivitis
• Tears flowing
• Blurred vision
• Sensitive to light, sensitive to wind, unable to stare at a computer or read for long periods of time. 
• You may also experience headaches or eye pain.

If you have these symptoms, you may have dry eye disease. You should see an ophthalmologist to find the cause and treat it as soon as possible for the safety of your eyes.