Written by Carol Petersen, RPh, CNP – Women’s International Pharmacy
Dry eyes can be very uncomfortable. People with dry eyes complain of burning, grittiness, redness and ironically, excessive tearing. Wearing contact lenses may be irritating, or even impossible, for people with dry eyes.
Why do eyes get dry?
Medical conditions such as arthritis, lupus, diabetes, sarcoidosis, and salivary gland disease can lead to dry eyes. In addition, the tendency to drink less water as we age, the dependence on soft drinks for fluid replacement, local water shortages and hot, dry weather can all lead to dehydration in the eyes.
Many medications also contribute to dry eyes. Antihistamines often cause dry and irritated eyes. Antidepressants like Prozac can cause dry mouth and eyes, causing vision problems. Drugs for dizziness, birth control pills, diuretics, and blood pressure medications all increase the chances of dry eyes.
Behavioral and environmental issues also contribute to dry eyes. Drinking lots of coffee, being around cigarette smoke, wearing contact lenses, spending time in buildings with air conditioning or heating, traveling in airplanes, being in ultraviolet light, staring at a computer screen, and not blinking can also cause dry eyes.
What are tears made of?
Tears are comprised of three different types of secretions:
- Oil, produced by the meibomian glands located in the eye lids, floats above the watery portion of the tears and keeps the eyes from drying quickly
- Mucous, produced by the goblet cells inside the eye lids, forms the layer in direct contact with the eye
- The watery portion, produced by the lacrimal glands, is sandwiched between the other two layers
Most of the products sold over-the-counter to treat dry eyes only replace the watery portion of tears and must be used with great frequency.
Hormones to the rescue?
It is becoming more apparent that disorders of the oil-producing meibomian glands may be the reason behind up to 75% of the complaints of dry eye. Research (and even United States patents) point to the lack of androgens, such as testosterone and DHEA, as the underlying problem with oil production in tears. Androgens control lipid production of the sebaceous glands in the body, including the meibomian glands. Eye drops and ointments or gels to be used around the eyes containing testosterone or DHEA have been the focus of studies, and have produced encouraging results.
What about estrogen?
Postmenopausal women tend to be more afflicted with dry eyes than men of the same age, which suggests that estrogens may be a contributing factor in dry eyes. However, the subject becomes much more complicated when considering different types and amounts of estrogens, estrogen mimics, xenoestrogens, and disturbances in estrogen metabolism. For example, a study published in the British Journal of Obstetrics and Gynecology (BJOG) involving a group of postmenopausal women found that estradiol drops were effective in relieving dryness, reddening, excessive blinking, itching, and feelings of foreign bodies among women in one group, while the oral estradiol valerate in the artificial tears group was not sufficient to relieve their symptoms. Another study evaluated tear production throughout the menstrual cycle and found that there were significant changes associated with hormonal fluctuations. However, dryness and inflammation seemed to be the most significant during estrogen peaks.
And in our canine friends?
More than 60 species of dogs suffer from dry eyes and have constant problems with mucous accumulation. A veterinarian discovered that cyclosporin (an anti-rejection drug used by organ transplant patients) can be very effective when applied as an eye drop to a dog’s eyes.
- “There won’t be an eye moist” by Dr. Thomas Kron; Article #193302 on Doccheck.com; March 24, 2010.
- The Eye Care Revolution by Dr. Robert Abel, Jr., MD; Kensington Publishing Corp; New York, NY; 2004.
- U.S. Patent Number 6,659,985 submitted by Charles Gerald Connor; December 9, 2003.
- “Treatment of menopausal keratoconjunctivitis sicca with topical oestradiol” by Sator, et al; BJOG: An International Journal of Obstetrics and Gynaecology, Vol. 105, pp 100-102, Jan 1998.
- “Ocular surface changes over the menstrual cycle in women with and without dry eye” by Versura, et al; Gynecol Endocrinol, 2007 Jul:23(7):385-90.