According to nutritionist Paavo Airola, we should not eat potatoes that have any green tint and he mentioned a toxin called solanine (a nerve toxin) as the reason why. Potatoes often develop this green tint after exposure to light in the supermarket, but farming and harvesting practices play a role as well. It was recently confirmed that potatoes that have developed this slight green tint contain a naturally occurring toxin called glycoalkaloids (GA) and pose a risk to public health, according to a review paper published in the latest online issue of SCI's Journal of the Science of Food and Agriculture (JSFA). The toxin that is usually found in these green-tinted potatoes can even lead to neurological disorders, among other problems. See more at these links:
The last thing anyone with glaucoma (an optic neuropathy) should want to do is to consume a potential nerve toxin.
I always store my potatoes in the dark. But it turns out that more recent research shows that lighting in supermarkets (or your home produce storage area) affect many common vegetables. According to various studies undertaken by researchers from the University of La Rioja, exposure to light reduces the quality of cauliflower, broccoli, chard, leeks and asparagus, which have been processed for sale.