In vivo studies have shown that anti-oxidant phytochemicals from Gou Qi Zi (Lycium barbarum fructus, aka Chinese wolfberry or goji berry) can protect eye tissues from oxidative damage. American researchers studying type-2 diabetic mice observed that wolfberry extract could protect retinal pigment epithelial cells from the oxidative stress caused by hyperglycaemia. The researchers have previously shown that goji berries contain high levels of zeaxanthin, lutein, polysaccharides and polyphenolics, all of which demonstrate anti-oxidant activity in vitro. On a molecular level, the extract was shown to activate AMPK (a key metabolic enzyme involved in glucose uptake and cellular energy homeostasis) and reduce the damaging effects of oxidative stress on the endoplasmic reticulum that would otherwise lead to cell death. Oxidative stress is a leading cause of diabetic retinopathy, which is a common complication of type two diabetes and a major cause of blindness. The researchers suggest that goji berries consumed as a dietary supplement may therefore help protect vision. (Antioxidative activity of polysaccharide fractions isolated from Lycium barbarum Linnaeus. Int J Biol Macromol. 2009 Aug 1;45(2):146-51. http://www.humec.k-state.edu/news/2010/04/09/lin-links-wolfberries-to-vision-improvement/).