Strabismus

Strabismus, more commonly known as cross-eyed or wall-eyed, is an eye muscle condition in which one or both eyes may turn in (esotropia), out (exotropia), up (hypertropia) or down (hypotropia).

The eyes are not properly aligned and do not focus on an object together at the same time. One eye may be turned all of the time or only some of the time. Most people who have strabismus are usually born with it or develop it at an early age. However, some forms of strabismus occur later in life.

Symptoms:

Newborns often have crossed eyes to some degree due to underdeveloped vision, but this usually disappears by the age of 3 to 4 months. True strabismus does not disappear as the child grows. If you think your child is showing signs of true strabismus, it is important to seek the advice of an eye care professional. The earlier the detection and treatment, the better the child's vision will be. Symptoms to watch out for include:

• Eyes that appear crossed
• Eyes that do not align in the same direction
• Eyes that do not move together
• Double vision
• Vision in only one eye, with loss of depth perception

Causes:

Strabismus is caused by a weak eye muscle or a weak signal from the nerve that controls the eye muscle. Frequently, uncorrected farsightedness and focusing problems are the underlying causes of strabismus in children. Some children are born with a defective visual processing center in the brain. Strabismus may also develop if a child is born with a cataract. It is common in conditions such as Down’s syndrome and cerebral palsy. Bleeding in the brain, a brain tumor, nervous system disorders, diabetes, high blood pressure, myasthenia gravis, thyroid disease and severe vision loss can also cause strabismus.

Risk factors:

One of the highest risk factors for strabismus is having a family history of strabismus. Having a moderate to high amount of farsightedness at a young age can also increase the risk significantly, as does having a disease such as diabetes or high blood pressure. In addition, strabismus may develop as a complication of any other disease causing vision loss.

Types:

Strabismus is categorized as being either constant (turned in all of the time) or intermittent (turned in some of the time). Cases of crossed-eyes, or esotropia, are classified as either "congenital" or "accommodative" esotropia.

• Congenital esotropia: An uncommon condition in which a baby is born with an inward turn of a large amount, usually appearing between the ages of 2 and 4 months.
• Accommodative esotropia: An inward turning eye that occurs because the eye is attempting to compensate for uncorrected farsightedness or a focusing disorder.

• Diagnosis:

  Besides parents, a pediatrician or family doctor is often the first person to detect strabismus. A baby whose eyes do not appear straight by the age of 3 to 4 months should be examined. To properly diagnose strabismus, a complete eye examination must be performed by an eye doctor. Early diagnosis is very important, as some eye turns may be a result of a serious medical condition. Strabismus that is not treated early in a child’s life may cause amblyopia (lazy eye), a condition in which vision develops poorly. In addition, the cosmetic appearance of strabismus may cause a lack of self-esteem.

  Treatment:

  Strabismus cannot be outgrown. Treatment to straighten the eyes is required. Treatment will depend on the type of strabismus and its cause:

  • Glasses may be prescribed to improve focusing and enable the eyes to straighten.
  • Patching the good eye will force a patient to use the affected eye. Patching will improve the chances of normal vision to develop.
  • Eye drops may be used to blur the good eye, forcing the affected eye to be used. (This achieves the same result as patching.)
  • Eye muscle surgery may be an option if non-surgical treatments do not work.
  • Some eye doctors may prescribe eye exercises before or after surgery.
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  •                   Albinism  Child's Eyes

    If your child has just been diagnosed with albinism, you may be wondering how the condition might affect his eyes and vision. Albinism is an inherited disease that can affect both the eyes and the skin, but sometimes it only affects the eyes. People with albinism typically have little to no pigment in their skin and hair.

    Albinism can sometimes have profound effects on vision and eye health. The disease can affect the amount of pigment present in the back of the eye as well as the development of the neural connections between the eyes and the brain, causing problems such asnearsightedness, astigmatism, light sensitivity, and glare. Fortunately, eyeglasses may significantly improve your child's overall eye problems.

    Albinism and Eye Color

    Children with albinism usually have blue eyes, but some have brownish-colored eyes. Some children will even appear to have pink or red eyes, because the iris doesn't contain much pigment. The pinkish color results due to a lack of pigment in the iris. The inside of the eye will also appear very light because the eyes lack the pigment that is contained in the layer directly beneath the retina.
    

    Albinism and Refractive Errors

    Children with albinism tend to be nearsighted or farsighted and often have large amounts of astigmatism. Glasses or contact lenses can be used to correct these vision problems.

    Albinism and Light Sensitivity

    Children with albinism can have profound light sensitivity. In a normal eye, the iris helps to shield the retina from bright light. When a child has albinism, their iris is sometimes so light in color that it can't properly control the amount of light that hits the retina. Also, because the back of the eye also lacks pigment, light is not absorbed properly and scatters, creating more light sensitivity. These children require sun protection, including quality sunglasses or tinted contact lenses.

    Some children with albinism may benefit from a permanent tint in their prescription eyeglasses that is light enough to function indoors. Children with albinism may also benefit fromphotochromic lenses. Photochromic lenses darken to a grey or brown shade when in sunlight and automatically lighten back to clear indoors. Many different types of photochromic lenses are available today and they may benefit from photochromic lenses that turn darker outside but do not necessarily lighten up completely when indoors. They remain slightly tinted indoors.

    Albinism and Glare

    Glare is light that is reflected off surfaces such as water, waxed floors and white sand. Glare can make even the cloudiest day uncomfortable for children with albinism. Because glare can be debilitating to these children, polarized sunglass lenses are highly recommended. Polarized sunglasses reduce not only the amount of light that enters the eye but they also virtually eliminate associated glare. Polarized lenses can make children with albinism much more comfortable and deliver a much better visual experience for them. Polarized lenses are available in many different colors and are available in both constant tints and photochromic options.

    To further enhance comfort for children with albinism, many doctors and opticians recommend adding a mirror coating to their sunglass lenses. A mirror coating will reduce the amount of light that reaches the eyes even further and deflect the light that bounces up and enters the eye from below.

    Albinism and Other Vision Problems

    Children with albinism may also develop other vision problems that will require attention, such as nystagmus and strabismus. Nystagmus is an involuntary flicker of the eyes. Nystagmus usually causes a child to make quick, jittery movements by both eyes. Strabismus is an eye muscle condition that causes one or both eyes to turn in, out, up or down.
    

               Vision Screening for Kids

    
    

    An evaluation of your child's eyes should occur at all well child visits, even as an infant.

    Routine vision screening is important, because many abnormalities are treatable if discovered early, and untreated, can lead to vision loss and blindness. Among the vision problems that your Pediatrician will evaluate your child for include:

    • strabismus - a misalignment of the two eyes, affecting about 4% of children. Strabismus is usually described by the direction of misalignment, which can be outward (exotropia), inward (esotropia), upward (hypertropia) or downward (hyotropia). A child may also have a phoria, with eye deviation only when one of the eyes is covered or when he is tired or sick.
    • amblyopia - reduced vision in an eye, which can be secondary to strabismus, anisometropia (unequal refractive errors in both eyes, for example, if one eye is more farsighted than the other eye), congenital cataracts, etc.
    • refractive errors - such as myopia (nearsightedness) and hypermetropia (farsightedness).

    In younger children, a vision evaluation will usually consist of an examination for the red reflex (checks for cataracts and retinoblastoma), eye alignment (misaligned eyes may indicate strabismus) and eye movements. Older children, beginning at three years of age, should have a more formal test of their vision. Until formal vision testing is possible after three years of age, younger children's vision can be assessed by observation of how they fixate and track objects and by the history of the child's parents. Visual milestones for infants include being able to follow an object to midline in the first 2-6 weeks, past midline by 1-3 months, and follow an object 180 degrees by 3-5 months. If your child isn't meeting these developmental milestones on time, then you should see your Pediatrician for an evaluation.

    
    

    Other testing may include the corneal light reflex test, in which a light is directed at the bridge of the nose and the light reflex is examined to make sure it is symmetrical or shines in the same spot on both eyes. If the light reflex is off-center or not symmetrical in both eyes, then it might indicate a misalignment of the eyes. This is useful to differentiate pseudostrabismus, a condition in which the eyes appear to be misaligned because of prominent epicanthal folds or a broad nasal bridge and which doesn't require treatment, from true strabismus.

    The unilateral cover test can be used to determine if an infant or young child will follow an object while one of the eyes is covered. For example, your Pediatrician can see if your child can fix on and follow a toy with both eyes, and then cover the left eye and see if he continues to follow it with his right eye. Then, the right eye is covered to see if he will follow the toy with his left eye. If he gets really fussy or refuses to follow the object when you cover one of his eyes, then that may indicate that the vision in the other eye is reduced.

    In older children, the unilateral cover test is also useful to check for strabismus. While the child is looking at a distant object, such as an eye chart or toy, cover one of his eyes. If the other eye moves outward or inward, then that might indicate that his eyes are misaligned and that he has strabismus. The test is then repeated by covering the other eye.

    Other problems that indicates the need for further evaluation include parents noticing that their child's eyes are crossing, that their eyes aren't straight or if they just don't seem to be seeing well. It is important to keep in mind that younger children usually don't report problems with their vision, especially if the problem is in just one eye and the other eye is accomodating for it. Older, school age children, may report that they can't see the board, or they may have frequent headaches, double vision or are frequently squinting. Formal testing of visual acuity is usually possible once a child is three years old, although 2 year olds may be able to be tested with picture cards