The condition is not dangerous or sight threatening. Most likely it is a small cyst of conjunctiva, the outer layer of the eye. They come and go, may be small or large, may be single or connect like a string of sausages. They look like small 'water blisters' or drops of water on the eye. Given your child's age removal would be difficult. In an adult its pretty simple and most will go away with a drop of anesthetic and antibiotics and sticking a couple of holes in it with a sterile needle. Reoccurences are not unusual. If the cyst is small leaving it alone may be the best course, removal would likely require extreme immobilization or exam under anesthesia.
JCH III MD Eye Physician & Surgeon