There can be many causes to changes in the color of the whites of the eyes in children. Some of these causes are common and not worrying, whereas others can be serious. The physicians most qualified to assist you with this problem are your pediatrician
or your ophthalmologist
A common cause of small yellow spots on the whites of the eyes is bruising, which results from the rupture of tiny blood vessels. As the bruise matures it goes from red to yellow in color. This discoloration is common in young, active children who might suffer bumps to the eyes and head.
Similarly, the eye can become 'tattooed' if the white part is scraped or traumatized by a pencil lead or other foreign object.
If the entire white part of the eye is yellow, that is a more serious problem called jaundice, which is caused by a systemic illness
and requires further investigation to determine the cause.
Rarely, yellow or other small discolorations of the eye can represent an atypical form of melanoma, which is a serious cancer of the pigmented cells of the body.
As always, diagnosis of this problem will require an examination by your physician. A visit to your pediatrician or ophthalmologist is strongly recommended.