N-Acetyl Carnosine (NAC) is a derivative of the dipeptide carnosine and has been investigated for its potential in eye health, particularly for age-related cataracts. The rationale for its use is based on its antioxidant properties, as oxidative stress is a known contributor to lens opacity and other degenerative changes in the eye. Several small-scale clinical studies, primarily conducted in Russia and published in the early 2000s, have reported that topical application of NAC eye drops (popularly branded as "Can-C") may slow the progression of cataracts and improve lens clarity. These studies suggest that NAC may act by reducing oxidative damage and glycation in lens proteins.

However, the overall quality and size of these studies are limited, with most lacking rigorous controls, large sample sizes, or replication by independent groups. Systematic reviews and ophthalmology organizations have generally concluded that while preliminary results are intriguing, there is insufficient high-quality clinical evidence to make definitive recommendations for NAC in the treatment or prevention of cataracts or other causes of poor eyesight. Further research in the form of well-designed, large-scale randomized controlled trials is needed to confirm efficacy and safety.

In summary, there is some early scientific evidence supporting the use of N-Acetyl Carnosine for age-related eye conditions, but the evidence base is weak and not widely endorsed by mainstream medicine at this time.