Source: DGNews  |  Posted 1 year ago

SAN FRANCISCO -- March 3, 2010 -- Intriguing findings on hormone replacement therapy (HRT) and cataract risk are reported in the March issue of the journal Ophthalmology.

An 8-year prospective study of more than 30,000 postmenopausal Swedish women found that those who were using or had used HRT had significantly higher rates of cataract removal, compared with women who had never used HRT. Alcohol consumption seemed to increase HRT’s harmful effect.

The study, led by Birgitta E. Lindblad, MD, Sundsvall Hospital, Sundsvall, Sweden, was part of the Swedish Mammography Cohort (SMC), established to study lifestyle factors and chronic diseases.

“If future studies confirm the associations we found, increased risk for cataract removal should be added to the list of potential negative HRT outcomes,” said Dr. Lindblad.

More than 4,300 cataract removal surgeries were performed in participants between 1997 and 2005. The risk for cataract removal was increased by 14% in women who had ever used HRT and by 18% in current HRT users, compared with women who never used HRT. Longer duration of HRT use correlated with increased risk.

Current HRT users who also reported having >1 alcoholic drink per day had a 42% increased risk compared with women who used neither HRT nor alcohol. Smoking status did not significantly affect risk. Data were adjusted for exposure to external oestrogens such as birth control pills, as well as reproductive and other health factors.

“Cataract is more prevalent in postmenopausal women than in men at similar ages; this implies that hormonal differences are involved and suggests a possible role for oestrogen,” Dr. Lindblad explained. She described how HRT may act to promote cataracts and also compared her project’s findings with earlier studies.

Oestrogen receptors have been detected in the eye’s lens, the area that becomes cloudy and inflexible when a cataract develops. Naturally occurring oestrogen appears to protect the eye from cataract, along with guarding cardiovascular and other body systems before menopause. Exogenous oestrogens like those used in HRT do not function the same way. For example, HRT increases C-reactive protein levels, associated with cataract development in other studies. Dr. Lindblad’s study also describes how alcohol and HRT may interact to raise estradiol levels, which appears to affect cataract risk.

In contrast to the SMC, earlier large HRT and cataract risk studies in the United States, Australia and Europe reported mixed results; importantly, some of these studies included women who were premenopausal and so possibly protected by endogenous oestrogen.

Results of the Swedish study may have been impacted by factors unique to this population: for example, nearly all participating women shared the same ethnicity, and all had equal access to care. The study did not identify type of HRT, type of cataract, or measure exposure to excess sunlight (a risk factor for cataract, although unlikely to impact residents of northern Europe).

SOURCE: American Academy of Ophthalmology