A good rule of thumb is the summer before they begin kindergarten or first grade, provided you are not noticing anything suspicious that a problem exists earlier than that (for example: an eye turn, squinting, holding reading material close in, frequent headaches).

It is important to note that many kids with problems may pass some school screenings. They could be significantly far-sighted and still pass a distance acuity test. A far-sighted child may have problems with reading comprehension. What is really a vision problem can masquerade as a learning disability.