I don't think that is true, if it were true very many Indians and mexicans would be blind. Since time in memorial indians have used chillies in practically every food they prepare, and so far i haven't seen or heard an indin has gone blind because of taking a lot of chillies. If anything and from what i have heard over the years, chilli is good for you especially for digestion. I cannot count how many people i have seen taking chilli for the longest time in their lives, and they are so healthy it's unlikely to hear them complain that they are sick. I think it is medicine on it's own. I am one of those people who have been taking chilli for the longest time, and sometimes when i eat food without chilli it tastes flat with no flavor, so that tells you one thing, that it adds flavor to food. The only time you will feel your eyes go blurry is when you eat very hot chilli and your not used to, because your head will be spinning for sure. Maybe Indians should come out amd expound on this.