Strabismus (eye turn, crossed eye)

Picture of right exotropia (eye turn out)

Strabismus (also known as an eye turn, wandering eye, crossed eye, or wall eye) is a lack of coordination between the eyes. The eyes cannot work together, like most people’s eyes do, so they drift apart and look in different directions. This causes the brain to receive double images. If not treated early, strabismus can lead to loss of vision or amblyopia (lazy eye) where the brain suppresses, or ignores one of the images to avoid seeing double. As a child gets older, the likelihood of restoring this vision decreases. Crossed eyes can also have negative implications for a person’s self-confidence and social interactions.

Strabismus can result because of:

• improper development of eye muscle coordination in infants and children
• brain injury such as trauma, stroke or aneurysm that causes a paralysis of a nerve that controls the muscle
• problems with the nerves or muscles that control eye movement
• excessive farsightedness (hyperopia), or a large difference between the vision of each eye

Strabismus Classification

Strabismus is classified by the direction that the “wandering eye” turns.

• Esotropia: eye turns in
• Exotropia: eye turns out
• Hypertropia: eye turns up
• Hypotropia: eye turns down
• Intermittent (i.e. when tired or after prolonged reading or computer use)
• Alternating (between right and left eye turn)

Pseudo-strabismus, a fake strabismus, can occur in newborns. A child’s eyes may drift in and out of alignment because he has not developed bilateral integration or coordination of his eyes. The eyes usually straighten as the infant’s visual system develops. Infants also often have a wide, flat nasal bridge and a fold of skin at the inner eyelid that tends to hide the eye when looking to the side, thus creating the illusion that the eyes are turned inwards. A Developmental Optometrist can easily distinguish a true strabismus from a pseudo-strabismus.

Early treatment for strabismus, is very effective, especially if one of the reasons that the eyes turn inwards is due to a high amount of hyperopia or farsightedness. If not treated early, this can result in an eye turn inwards, called Accommodative Esotropia by age 2-3 years old. This occurs because when eyes are under powered, as in hyperopia, they converge when focusing. At first, the eye turn is intermittent, but may become constant when left untreated.

Strabismus is one of the reasons that the American Optometric Association recommends a child’s first vision exam is given at 6 months old, and yearly thereafter. Another important reason to begin annual vision exams during infancy, is that it is nearly impossible for parents to know whether their child’s vision is normal, whether the eyes are tracking or teaming correctly, and it is impossible for a child to know what “normal” looks like; therefore, she would not know to tell her parents that she does not see correctly.

Strabismus causes problems such as:

• Amblyopia
• Double vision
• Blurry vision
• Ghost images
• Impaired depth perception or 3D vision
• Eyestrain
• Difficulty reading
• Difficulty catching a ball
• Difficulty driving or parking a car
• Impaired ability to judge distances or localize where objects are in space
• Difficulty focusing on visual tasks
• Difficulty focusing on the person you are looking at

The goals of treatment for strabismus are restoring 3-dimensional vision, functional vision, eye alignment, and restoring vision to the eye that is misaligned. Treatment options for strabismus include:

• Vision Therapy
• Patching
• Eye muscle surgery
• Glasses which may incorporate prism
• Removing a cataract, or correcting another problem that is contributing to the eye turn

Vision Therapy may be necessary after eye muscle surgery to restore full visual function such as depth perception.

Vision Therapy is an individually customized type of physical therapy program for the eyes to train eye muscle control and coordination. Vision Therapy also works on stimulating the visual system to function normally. Vision Therapy sessions include procedures designed to enhance the brain's ability to control:

• eye alignment
• eye teaming
• eye focusing abilities
• eye movements
• visual processing

Visual-motor skills and endurance are developed through the use of specialized computer and optical devices, including therapeutic lenses, prisms, and filters. During the final stages of therapy, the patient's newly acquired visual skills are reinforced and made automatic through repetition and by integration with motor and cognitive skills.

While vision therapy includes the eye muscle training methods of orthoptics, it has advanced far beyond it to include training and rehabilitation of the eye-brain connections involved in vision. Clinical and research developments in vision therapy were closely allied with developments in neuroscience during the twentieth century. Research continues in the 21st century.

In vision therapy programs, optometrists look at the neurological control system to treat the whole visual-motor system and alter reflexive behavior, which results in a lasting cure. Vision Therapy for strabismus generally consists of either weekly or bi-weekly office based therapy under the supervision of a Vision Therapist and Developmental Optometrist to make sure the procedures are accurately performed and progress is monitored. We also prescribe home therapy to reinforce in-office therapy and accelerate treatment.

If you have any questions about Strabismus or Vision Therapy, please call our office.