Prominent eyes may be a family trait. But prominent eyes are not the same as bulging eyes. Bulging eyes should be checked by a doctor right away.
Bulging of one eye, especially in a child, is a very serious sign. It should be checked immediately.
Hyperthyroidism (particularly Graves disease) is the most common cause of bulging eyes. With this condition, the eyes do not blink often and seem to have a staring quality.
Normally, there should be no visible white between the top of the iris (the colored part of the eye) and the upper eyelid. Seeing white in this area usually is a sign that the eye is bulging.
Because eye changes develop slowly, family members may not notice it until the condition is relatively advanced. Photos often draw attention to the bulging when it may have gone unnoticed before.