There are three main types of strabismus.

• Esotropia. The most common form of childhood strabismus is "crossed eyes," or esotropia, in which one eye turns inward, toward the nose, instead of looking straight ahead. Esotropia often appears early, in infants or very young children.
• Exotropia. Exotropia, commonly called walleye, is a form of strabismus in which one eye turns outward, toward the temple. Symptoms of exotropia usually begin between the ages of 1 and 6 years.
• Hypertropia. Also called vertical deviation, hypertropia is a form of strabismus in which one eye turns upward, toward the eyebrow. It is a far less common form of strabismus.