SSRIs do not increase cataract risk
Selective serotonin reuptake inhibitors (SSRIs) do not appear to promote the development of cataract in users, according to a case-control study.
Researchers examined 206,931 cataract patients aged ≥40 years and similar number of matched controls. Data on the number of SSRI prescriptions and prescriptions for other antidepressant drugs were obtained and analysed using conditional logistic regression. Adjustments were made for body mass index, smoking, hypertension, diabetes and systemic steroid use.
Results showed no association between current long-term use of SSRI (≥20 prescriptions) and an increased cataract risk (adjusted odds ratio [OR], 0.99; 95 percent CI, 0.94 to 1.03). However, in a subset of patients aged 40 to 64 years, long-term SSRI users demonstrated a slightly increased risk of cataract compared with nonusers (adjusted OR, 1.24; 1.15 to 1.34).
The observed increase, however slight, in the odds of developing cataract among long-term SSRI users aged 40 to 64 years warrant additional studies, researchers said.
A monoamine neurotransmitter found primarily in the gastrointestinal tract and the central nervous system, serotonin functions to regulate mood, appetite and sleep. It is also located in the aqueous humour of patients with ocular complications such as cataracts and glaucoma, and serotonin binding proteins are found in the lens of animals. [Can J Ophthalmol 2014;49:e112–e114]
While not fully understood, the mechanism underlying the association between serotonin and cataract is said to potentially involve melatonin (one of the downstream products of serotonin), although the hormone plays a protective role. Melatonin is sequentially synthesized from serotonin in the pineal gland and functions in the regulation of the circadian system. The hormone also acts in the ocular lens as an antioxidant and radical scavenger, and has been shown to protect against cataract formation in rats. [Can J Ophthalmol 2014;49:e112–e114]
Although having a relatively good safety profile and few reported ophthalmologic sequelae resulting from their use, several studies have reported that serotonin, melatonin and their receptors have a role in cataractogenesis. This highlights the possibility of SSRIs affecting the concentration of serotonin and melatonin in the aqueous humour. [J Pineal Res 2007;42:92-6; Mol Vis 2008;14:2143-7]