In general, pinguecula does not threaten the vision, even though it may lead to red eyes and discomfort in the eyes due to irritation and inflammation. You can drip some prescribed artificial tears to relieve the discomfort and alleviate the sensation of a foreign body in the eye. And you should try not to expose your eyes to the bright sunlight. You can protect your eyes by wearing sunglasses when going out.
No, it is impossible to have vision loss from pinguecula. Pinguecula is a conjunctival degeneration, which is not cancerous. It is a yellowish bump of thicker fiber degenerated from collagen in eyes, often occurring on the side near to nose. It is not a tumor but just a deposit of protein and fat. It won't grow onto the cornea. According to research now, it might be caused by long time exposure to UV rays or chronic eye irritations. Usually it is not so harmful but annoying. It brings irritations but grows very slow and will lead nothing serious problem. It is very common for aged person. Some people thought it makes them look old and there is a cosmetic surgery procedure which can remove the pinguecula.
Yes, it is possible for you to get blindness because of pinguecula. The pinguecula belongs to the hereditary disease. The senile change inflammation is caused by venereal change. You should protect the eyes very carefully. Or else the serious pinguecula will cause the damage of the eyes nerves which could cause your blindness. You need to protect the eyes carefully.