Are there any side effects of hair loss shampoo?

These days, I often see posts from people using hair loss shampoos and some recommending them, so I am interested in hair loss shampoos. However, my father has been using a hair loss shampoo and seems to have experienced a decline in his eyesight, which makes me a bit worried. My father originally started losing hair early and only has some hair left on the back of his head, but after using the hair loss shampoo, he felt that his hair seemed to have become thicker. Of course, I remember that he used it for more than a year, not just a month or two. He thought the technology had improved so much and continued using it. But one day, he started feeling that his eyesight had worsened significantly, and driving became uncomfortable. Since there was no reason for his eyesight to deteriorate, he checked the shampoo's packaging and found a warning that it could possibly cause vision problems. After that, he stopped using the shampoo and went to an ophthalmologist, where he underwent cataract surgery. So, my father thinks... it’s like the saying "when the crow flies, the egg falls," meaning it was the right time for cataracts, and he wonders if the shampoo usage might have been related. However, since then, he feels uneasy and no longer uses hair loss shampoo.

There are also stories that frequent dyeing can affect eyesight. I wonder if hair loss shampoo has any impact as well.