Q: Can N-acetylcarnosine eye drops dissolve cataracts, as marketers say? A: Some animal studies and a few human trials suggest the drops may help reverse lens cloudiness, the hallmark feature of cataracts—but claims that they are a cataract cure are overstated, at best. The Food and Drug Administration (FDA) has not approved any form of carnosine for the treatment of cataracts. (Carnosine is also sold as a dietary supplement, promoted for eye health and many other disorders.) Various carnosine-related compounds, including N-acetylcarnosine (NAC), occur naturally in the body. When applied in eye drops, NAC makes its way to the interior of the eye, where it may have antioxidant effects. Oxidation of lipids in the lens of the eye is thought to contribute to cataracts. NAC may also help prevent “cross-linking” of proteins, another factor behind cataracts. In a study published in Clinical Interventions in Aging in 2009, people with cataracts who used NAC drops for nine months appeared to have an improvement in visual acuity and sensitivity to glare (a problem with cataracts), compared to those using placebo drops. But as with prior studies, this one was relatively small—and there are no data on long-term use. Moreover, nearly all of the research has been done by a Russian scientist who developed and holds a patent for a brand of NAC eye drops, called Can-C. Larger, better—and independent—studies are needed.