Strabismus, or crossed eyes, is a common condition that is defined as a state in which the eye turns or deviates when looking at a single object of interest. In simple terms, strabismus is a condition where both eyes do not look at the same object at the same time. Because of poor muscle coordination, eyes with strabismus turn up, down, in, or out when looking at an object.
Strabismus is common in newborn babies, though they tend to outgrow the condition. However, if an infant reaches 3 months old and still exhibits signs of strabismus, parents should consult a doctor. Strabismus affects about four percent of children below 6 years old. If crossed eyes occur all the time, it is called constant strabismus; if it is noticed only sometimes then it is called intermittent strabismus.
In order for both eyes to function normally, there are six muscles attached to each eye that control the eye’s movement. For people with strabismus, these muscles do not work together properly. Therefore, when one eye is looking at an object the other eye turns towards another object. In such case, two separate visions are sent to the brain. Overtime the brain starts to ignore the image from the weaker eye. Predicted causes of strabismus are:
Family history wherein risk increases if a parent or sibling has strabismus
Long-term uncorrected farsightedness
Down syndrome and cerebral palsy
Stroke or head injury
High blood pressure
Retinal damage in premature babies
Injury to eye
Tumor in brain or eye
Partial loss of vision due to disease or injury
Symptoms of strabismus can be noticed either around the clock or only when a child is tired or sick. Eyes will not move together or they might look misaligned. A child might complain of double vision or reduced vision. The parents might notice that their child lacks depth perception and blinks or squints often in bright sunlight. They might also notice that their child tilts his or her head to one side while looking at an object.
For normal vision it is important that both eyes concentrate on the same object at the same time. However, when the eyes see two different things as with strabismus, the brain eventually ignores images from the weaker eye. If this is continuous and is not treated when a child is young, then it might result in a condition called as amblyopia, where the weaker eye loses vision. This is the most serious result of strabismus.
An overview of the patient’s previous medical history and a physical examination is done to diagnose strabismus. The doctor will check the alignment of each eye and ask for symptoms parents observe, any other medical condition, or any medications taken recently.
A visual acuity test is done by having the patient read an eye chart from a distance to determine the extent to which the vision is damaged. A refraction test might be conducted to check the range for nearsightedness or farsightedness and to determine the appropriate power of lens needed to correct any refractive error. Alignment and focus testing assesses the movement of the eye. This test will focus on looking for the problem that is keeping the eye from working in unison. Alignment can be tested by a cover-uncover test that has the patient look at a particular object while the doctor observes his or her eye movement by covering and uncovering the object. In addition, the eye structure will be studied to rule out any other problem that could be causing strabismus. Both the internal and external eye will be assessed.
Children with strabismus have several options to correct their crossed-eyes.
Treatment can include:
Contact Lens or Eyeglasses: For children with uncorrected farsightedness, wearing glasses can help to focus effortlessly. This alone can correct strabismus in many patients.
Prism Lenses: These lenses are a special type of glasses or contacts that bend light to make the brain think the eyes are seeing the same vision, which reduces the turning of eyes.
Vision Therapy: This treatment is a visual activity program that trains the eye and brain to work efficiently together by rehabilitating eye-brain connection and strengthening eye muscles.
Surgery: Surgical treatment is common and can correct the length and position of the eye muscle for better alignment. After surgery a vision therapy might be required to improve eye coordination.
The earlier treatment starts the easier it is to fix strabismus. Usually treatment for correcting the eye goes on for many years. Sometimes, a single surgery might not correct the problem, and a child might require several surgeries. It is important that parents follow the doctor’s instructions carefully to help treatment be as effective as possible.
Strabismus is not a serious disease or illness, but misalignment of the eyes can lead to vision problems. Strabismus is very treatable, though vision loss due to amblyopia cannot be corrected. Results are most effective in children under 6 years old, so parents should make every effort to seek treatment for their children as early as possible.