discovering dry eye
Aging, Hormones And Dry Eye: An Update
BY KELLY K. NICHOLS, OD, MPH, PHD
Aging. On the positive side, getting older does allow for heightened wisdom, valuable experience and hopefully a feeling of confidence that comes with a job well done. But how does one age "gracefully?" Adding years does result in increased wear and tear on the body, including the tears.
Clinical diagnostic tests demonstrate changes in tear composition and stability with increasing age in patients without ocular surface disease. Total tear volume and tear production decreases, and tear osmolarity increases. These results indicate that tear film function declines throughout life. In patients with dry eye, the impact of the normal aging process may significantly affect dry eye symptoms and may exacerbate the disease.
Hormones and Dry Eye
There has been debate regarding the ocular effect of hormones over several decades. Postmenopausal women reportedly suffer more from dry eye than younger women. While the etiology of dry eye in postmenopausal women is unclear, hormones are suspected to play a role.
Research has shown that androgens, estrogens and progestins may influence the structure and function of many ocular tissues, including the lacrimal gland and anterior surface of the eye. The conjunctiva is reported to be sensitive to estrogen in menstruating and pregnant women. The lacrimal gland has receptors for androgen and prolactin, which have been shown to affect tear production. In addition, estrogen and glucocorticoids may have an indirect regulatory role in maintaining the tear film.
Topical hormones have been used experimentally for treating dry eye. Estrogen was applied in a gel formulation topically to the ocular surface in women with post-menopausal dry eye symptoms, and an improvement was found in symptoms and a few clinical tests (Akramian et al, 1998). In a similar study utilizing a placebo group, topical 17B-oestradiol ophthalmic drops were applied to the ocular surface in the treatment group (Sator et al, 1998). The authors found an improvement in symptoms, tear production and tear stability. They concluded that the topical drops were successful in treating dry eye and that the blood-eye barrier prevented systemic estrogens from acting on the conjunctiva. Currently, Allergan has a topical androgen drop under phase II FDA investigation.
Recently, the effect of hormone replacement therapy on many body systems has been featured in the news. In July 2002, investigators in the largest study of hormone replacement therapy (HRT), the Women's Health Initiative clinical trial, halted one arm of the study due to increased risk of adverse events in the group taking HRT. The results of this study sent shock waves through the media and medical profession, and will clearly impact how doctors council their menopausal patients in the future.
A study by Vavilis (1995) found a statistically significant difference in the cytological maturation of conjunctival cells in patients on HRT in comparison to those not receiving HRT, indicating that systemic HRT may play a role in the maintenance of the ocular surface. In contrast, Schaumberg et al (2001) reported that women taking estrogen-alone HRT were more likely to have dry eye than either women taking combination estrogen-progesterone HRT, or women not taking HRT.
Contact lens patients going through menopause may demonstrate changes in contact lens comfort and tolerance. To ensure continued success with lens wear, take a careful symptom history in patients who have recently discontinued HRT, or have added phyto-estrogens to their diet.
Dr. Nichols is assistant professor of clinical optometry at The Ohio State University College of Optometry in the area of dry eye research.