It's not uncommon for people to perceive floaters or specks in their vision, especially when looking at a bright light source like a flashlight. These visual phenomena are typically harmless and quite common. They are often referred to as floaters and are actually tiny substances or debris floating in the gel-like substance called the vitreous humor inside the eye.
Floaters can appear as small specks, dots, threads, or cobweb-like shapes that seem to move around as your eyes move. They cast shadows on the retina, which can become more noticeable when looking at a bright background, such as a white wall or a light source.
The tiny crystal-like particles you mentioned when looking closely at a flashlight beam on the floor might be dust particles or airborne particles that become more visible due to the illumination of the flashlight. When light hits these particles, it can cause them to reflect and scatter, making them more noticeable to the naked eye.
If you're experiencing an excessive number of floaters or if you have concerns about your vision, it's always a good idea to consult an eye care professional for a thorough examination. They can evaluate your specific situation and provide any necessary guidance or treatment if needed.