Looking directly at the sun for short periods of time doesn’t immediately cause problems, but years down the line you will start to notice a section of your vision start to become like a void, no color, no light, just a lack of sight.

Just because you don’t notice an immediate effect doesn’t mean you’re not causing harm. The human body is a wonder of redundancy, and having ways of compensating in the short term. But eventually those compensations start to fade.