Causes of dry eyes can be divided into:
1- Deficiency of tear film production
2- Evaporative Dry Eyes
1- Deficiency of Tear Film Production
There is defective lacrimal gland function with decreased aqueous tear production.It can be either Sjogrens syndrome or Non-Sjogrens syndrome.
Sjogrens disease or syndrome can be either primary or secondary Sjogrens syndrome... More information about Sjogrens Disease
The second category of tear film deficiency is non-sjogrens syndrome causes which are:
1- Age related which is the most common cause and mainly it occur after the age of 50 especially in female after menopause due to hormonal changes.
2- Menopause. It can cause dry eyes due to hormonal changes
3- Destruction to lacrimal gland like in infiltrative process to the gland or in infectious process, after surgical removal or after radiation of head and neck. Infiltrative process as in sarcoidosis, lymphoma or amyloidosis. Infectious process as in trachoma
4- Obstruction to lacrimal gland ducts which can occur after infection, conjunctival scarring which can occur following trachoma and cicatricial pemphigoid
5- Neurological lesions with decrease sensation of the cornea like Parkinson disease, multiple sclerosis, Bells palsy and Alzheimer disease
6- Lasik and dry eye
7- Xerophthalmia or Vitamin A deficiency which leads to loss of goblet cells and deficiency in mucin layer of the tear.
8- General health conditions such as diabetes mellitus, Rheumatoid arthritis, thyroid eye diseases and Systemic Lupus Erythematosus
9- Medications. You should have a list of all medications that you use even over the counter medications
There are many medications that can cause dry eye and these are some of them:
• Diuretics which are used commonly to treat high blood pressure. This medication acts by removal of excess fluid from the body so the body it dehydrated
• Angiotensin-converting enzyme (ACE) inhibitors which is used to treat high blood pressure.
• Antihistamines and decongestants.
• Sleeping pills.
• Birth control pills.
• Isotretinoin drugs which is used for treatment of acne. It can cause severe dry eyes and also dry mouth.