If you're a woman, you're more likely to get dry eye, especially as you get older. That's because your levels of estrogen and other sex hormones change so much over your lifetime.
For instance, you have a greater chance of getting dry eye when you go through menopause. It's a time of life when hormone levels, especially estrogen, go up and down.
For some women, eyes may get dryer at certain times during their monthly period, mainly when estrogen levels go up.
Experts aren't sure exactly how changing hormones affect dry eye. Some studies show that hormone replacement therapy (HRT) for menopause symptoms makes dry eye worse, while other studies show it makes it better. It does seem that women who take only estrogen are more likely to get dry eye, while those who take a combo of estrogen and progesterone (another female sex hormone) are less likely to get it.
Dry eye may also be made better or worse by androgens, "male" hormones like testosterone, which both men and women make. For instance, women with polycystic ovary syndrome (PCOS) often have dry eye. The disorder causes cysts and problems with ovulation because of too much androgens.
Whether you're a man or woman, lower androgen levels may affect how well certain glands make tears or the oily film that keeps the surface of your eye moist.
Changes in your levels of thyroid hormone, which is made by the thyroid gland in your neck, can also cause dry eye. The changes can be due to a thyroid-related autoimmune disease. If you have one, the immune system -- your body's defense against germs -- mistakenly thinks your thyroid gland is an enemy and attacks it.
For instance, Graves' disease is an autoimmune disorder that's linked in its early stages with high thyroid levels, but over time or after treatment may have low thyroid levels. People who have it may have trouble closing their eyelids, don't blink often enough, and also can't keep their tear levels up. The eyes may actually bulge forward. All of these problems can lead to dry eye.
Low insulin levels make it harder for your lacrimal gland to make tears. Taking insulin may reverse some of these problems.