EYE MUSCLE DISORDERS

Both children and adults can be affected with eye muscle disorders. Early detection in a child can prevent vision loss. Approximately 4% of all children in the United States have strabismus. It occurs equally in males and females.

STRABISMUS

Strabismus is a visual defect in which the eyes are misaligned. One eye may look straight ahead, while the other turns in or out, up or down. The misalignment may be present all of the time or it can come and go. And, the misaligned eye can even change. The exact reason for the misalignment of the eyes leading to strabismus is not fully understood.

Strabismus is a term that describes many eye muscle disorders.



Strabismus in Children

With normal vision, both eyes aim at the same spot. The brain then puts the two pictures into a single, three-dimensional image. This blending or fusing of the two pictures gives us depth perception.

There are several types of strabismus:

• Esotropia is an eye misalignment where the eye turns inward towards the nose. It can affect one or both eyes and can alternate between the two eyes.
  
• Exotropia is a misalignment in which the eye turns outward, away from the nose.
  
• Hypertropia is an upward gaze or appearance of the eye while the other eye stays straight and fixates normally.
  

When one eye turns, two different pictures are sent to the brain. In a child, the brain learns to ignore the picture from the misaligned eye, and sees only the image from the straight one. This causes poor vision in the misaligned eye. It takes away the ability to have and develop depth perception.

How is the diagnosis made?

Strabismus can be diagnosed during an eye exam. It is recommended that all children have their vision checked by their pediatrician, family doctor or ophthalmologist at or before their fourth birthday.

What are the treatment options?

Eyeglasses in some cases can be prescribed that may strengthen the weaker eye. Covering or patching the stronger eye is often used.

Surgery may be required to realign or balance the eye muscles.


What can a parent look for?

Parents can watch for one-eyed squinting when the children go outside into the sun. Abnormal head positioning, such as a chin tuck, or the head tilting to one side or the back, could possibly indicate a possible muscle imbalance.

Another technique for detecting strabismus in children is to watch for equal light reflexes in the child's pupils. Photographs with the child looking straight ahead at the camera, are good for determining if the light reflexes are equal or not.

If there is any question about whether or not your child has an imbalance, a visit with a pediatric ophthalmologist would be the best way to know for sure.

The most important thing for parents to remember is that strabismus can cause permanent loss of vision. Early diagnosis and treatment can keep this from happening.


STRABISMUS IN ADULTS

As discussed earlier, strabismus is a condition in which the eyes are misaligned and pointed indifferent directions. Most adults that have strabismus have had it since childhood.

However, strabismus can occur in adults that have had no childhood history of misalignment. If there has been no prior history, a doctor may evaluate the patient for medical or neurological causes such as:

• Diabetes
  
• Thyroid disease
  
• Brain tumors
  
• Strokes
  
• High blood pressure
  
• Head trauma
  
• other neurological disorders
  

What are the symptoms of adult strabismus?

If the strabismus has been present since early childhood, the symptoms are usually minimal. If it develops later, the most common symptom is double vision.

Other symptoms may be eyestrain, headaches, discomfort while reading, or holding their head in abnormal positions to focus on an object.


How is adult strabismus treated?

There is a common misconception that strabismus in adults is difficult or impossible to treat. Actually, adults with strabismus have many different treatment options including:

• Eye exercises
  
• Special glasses with prisms
  
• Botox injections
  
• Eye surgery
  

AMBLYOPIA - "Lazy eye"

Amblyopia is poor vision in an eye that did not develop normal sight during early childhood. It is sometimes called "lazy eye". Usually, only one eye is affected.

This condition is a common one, affecting about 2 or 3 out of every 100 people.

Amblyopia is caused by any condition that affects normal use of the eyes and visual development. In many cases, the conditions associated with this problem are inherited. Children in a family with a history of amblyopia or misaligned eyes should be checked by an ophthalmologist early in life.

Amblyopia occurs most commonly with misaligned or crossed eyes. The crossed eye "turns off" to avoid double vision and the child uses only the better eye. An eye disease such as a cataract may also lead to amblyopia. Any factor that prevents a clear image from being focused inside the eye can lead to the development of amblyopia.

How is it treated?

To correct this problem, a child must be made to use the weak eye. This is usually done by patching or covering the strong eye, often for weeks or months. Even after vision has been restored in the weak eye, part-time patching may be required over a period of years to maintain the vision.

Eyeglasses can be used to treat amblyopia and may also be used along with patching to improve vision.

In another form of therapy for amblyopia, the doctor may use special eye drops to blur the vision in the good eye, which would force the child to use the weaker eye for focusing.

The good news is that the loss of vision is preventable. The success also depends on how severe the amblyopia is, and how old the child is when the treatment is started. If the problem is detected and treated early, vision can improve for most children.