Does Viibryd Cause Cataracts?
Can you believe everything you see on TV? Well no-but stay tuned. Some types of age related cataracts do display a higher concentration of serotonin as part of their molecular composition. The connection to prescription drugs that alter serotonin is a little more complex that it appears to be at first glance. The new blockbuster antidepressant vilazodone hydrochloride was released in the US market in July 2011. It falls under the category of SNRI, or a serotonin norepinephrine re-uptake inhibitor. Serotonin crosses between nerve endings to relay its message to the brain. When it is released there is also an adjacent site to reabsorb it before it crosses the gap in the nerve ending. Re-uptake inhibitors interfere with this site thus increasing the amount of “feel good” serotonin to pass along the message. After the Prozac generation of drugs, modifications were designed to also boost norepinephrine and dopamine, two other substances related to mood. Effexor, Cymbalta, Pristiq, and now Viibryd are the current SNRI medications. Viibryd claims to be unique in both blocking the re-uptake of serotonin and stimulating the serotonin receptor (type 5-HT1A).
The Eye Is An Outgrowth Of The Brain
The eye is developmentally an outgrowth of neural tissue and it is no surprise that there are a number of different types of serotonin receptors found in the different layers. The iris, ciliary body, cornea, lens,retina, central retinal artery and the ciliary artery all have serotonin receptors. The ciliary body (the root of the iris) has receptor cells that both increase the eye pressure and decrease it. There is some speculation that inadequate transformation of serotonin to melatonin by the ciliary body may lead to glaucoma. The human lens synthesizes melatonin which is known to be an antioxidant. Antioxidants like melatonin can prevent the damage free radicals inflict on lens proteins.
There is at least on type of serotonin receptor in the lens but this is not a well studied area. In animal models, serotonin disrupts enzymes (ATPase) that help provide energy to the lens epithelium (surface cells). With the loss of energy needed to keep cells healthy the lens starts to develop cataracts. Activation of serotonin receptor sites in the lens epithelial layer may also provoke cataract formation.
The fluid in the front half of the eye (aqueous humor) contains serotonin, presumably produced from the ciliary body and iris of the eyes. The lens may produce some serotonin but it probably receives most of its exposure from serotonin absorbed from the aqueous humor fluid. Taking a prescription drug like Viibryd has blocks the receptors in the brain and the receptors in the eye. Prozac has been shown to cause a transitory increase in eye pressure and in pupil dilation from blocking the re-uptake of serotonin receptor sites.
Eye Doctors Find Increase In Cataracts With Antidepressant Use In Study
A study in Vancouver in 2010 found a 15% increase in cataract formation in a large population of patients taking antidepressant drugs in the SNRI and SSRI categories. drugs. Effexor and Luvox were the worst offenders. Smoking is a known cause of cataracts and was not accounted for in this study. It is by no means a definitive study or the final word ion the subject.
Now the complicated part. There are seven known types of serotonin receptors with a number of subcategories. There are different mechanisms and activities for each one of these. The effect of Viibryd and other serotinergic type drugs on each receptor type is not completely known. SNRI drugs act in scattered small areas of the brain. The action of Viibryd is not completely known. The effect on receptors in the eye is largely unknown. It is not possible to say that Viibryd has any effect on cataract development with any degree of certitude.
Worrying Won’t Help Your Mood Or Your Eyes
Returning to reality, the 2010 study found only a 15% increase in the incidence of cataracts. That does not mean the antidepressant drugs increased your likelihood of getting cataracts by 15%, it is more like a 3% increase. When you factor in smoking, for all we know Viibryd might prevent cataracts. The activity on the the multiple types of receptor cells is not fully quantified. To my knowledge there has not been a reported association between Serotonin Syndrome and the acute .onset of cataract formation. Serotonin Syndrome occurs from an overdose of serotonin and you would expect to see this if SNRI drugs did cause cataracts.I have seen patients in my Fort Collins optometry practice that have been on SSRI and SNRI prescriptions for over 20 years with no signs of associated cataracts. This category of drugs is generally not considered a risk factor for cataracts by most eye doctors. Like any prescription you need to discuss the risks and benefits with your doctor. And most importantly help a friend quit smoking – smoking does cause cataracts, glaucoma, macular degeneration, and contributes to multiple other disease that result in blindness