School vision screenings are a useful first step, but they mainly check distance vision. A comprehensive eye exam looks at the visual skills that support reading and learning, such as focusing and how the two eyes work together, as well as the health of the eyes. It can pick up things a quick screening may miss.
If your child did not pass a screening, or you still have concerns after a pass, an exam is a good next step. Squinting, sitting close to screens, rubbing eyes, headaches, or losing their place while reading can all be signs to mention. Children often adapt without complaining, so your observations are valuable.