Nov. 06, 2014
Cataract surgery rates in the United States have more than doubled over the last 20 years — a rate faster than can be explained by aging demographics alone. The rate of increase has accelerated even more for women.
A population-based Canadian study published in Ophthalmology in 2010 suggested an association between the use of selective serotonin reuptake inhibitors (SSRIs) and the diagnosis of cataract. An association between serotonin and cataract formation is plausible, as serotonin receptors have been identified in the crystalline lens, and increased serotonin levels have been shown to cause lens opacities in animal models.
A research team led by Jay C. Erie, M.D., with the Department of Ophthalmology at Mayo Clinic's campus in Rochester, Minnesota, recently conducted a population-based, case-control study to investigate an association between SSRI use and incident cases of first-eye cataract surgery within a defined American population. Study results were published in the American Journal of Ophthalmology in 2014.
SSRIs are the most commonly prescribed antidepressants in the U.S. Estimates indicate that 1 in 4 women over age 50, and 10 percent of all U.S. residents, are prescribed antidepressants, primarily SSRIs and serotonin norepinephrine reuptake inhibitors (SNRIs).
"Given the increasing use of antidepressant medications in the last decade, an association between SSRI use and cataract surgery rates would be useful information," says Dr. Erie. "This study is an excellent fit for the Rochester Epidemiology Project database, which links and archives the medical records, medical diagnoses, prescriptions, surgical interventions and demographic information of virtually all people residing in Olmsted County, Minnesota."
Retrospectively identified cases included 6,024 county residents age 50 years or older who underwent first-eye cataract surgery between Jan. 1, 2004, and Dec. 31, 2011. Controls included 6,024 residents who never had cataract surgery and were matched to cases by age, sex and date of surgery.
Logistic regression models were used to compute odds ratios for differences in SSRI use between cases and controls, and were adjusted for age, sex and potential confounding variables, including diabetes and steroid use. Analysis showed:
- After adjusting for age and sex, the use of SSRIs for more than one year was significantly associated with incident cataract surgery (odds ratio [OR] 1.36, 95 percent confidence interval [CI] 1.23-1.51; P < 0.001).
- The association between SSRI use and incident cataract surgery was significant for men (OR 1.34, 95 percent CI 1.12-1.61) and women (OR 1.37, 95 percent CI 1.22-1.55) and remained significant after adjusting for cataract formation risk factors, including diabetes mellitus and steroid use (P < 0.001).
- Use of selective SNRIs also was significantly associated with incident cataract surgery (OR 1.37, 95 percent CI 1.11-1.70).
Further studies are warranted to confirm and understand these findings. "Using these resources, we found that cataract surgery in people age 50 years or older was significantly associated with an increased use of SSRIs," says Dr. Erie. "The risk was highest with the use of citalopram. The associations were similar in women and men. Our findings confirm the earlier Canadian study."
The research team noted some limitations in data interpretation:
- The study assessed cataract surgery rather than actual cataract formation.
- Drug formularies and prescribing patterns vary across health care practices and may influence the choice of specific medication within the SSRI and SNRI drug groups.
- Smoking status and exposure to secondhand smoke could not be controlled.
"The association between SSRI use and cataract surgery does not prove causation and should not be taken as reason to avoid or discontinue SSRI therapy. However, the possibility that the observed recent increases in SSRI use is contributing to accelerated growth of incident cataract surgery in our population, especially for women, cannot be excluded," says Dr. Erie.
For more information
Etminan M, et al. Selective serotonin reuptake inhibitors and the risk of cataracts. Ophthalmology. 2010;117:1251.
Erie JC, et al. Selective serotonin reuptake inhibitor use and increased risk of cataract surgery: a population-based, case-control study. American Journal of Ophthalmology. 2014;158:192.