Amblyopia, more commonly known as lazy eye, is the eye condition noted by reduced vision not correctable by glasses or contact lenses and is not due to any eye disease. The brain, for some reason, does not acknowledge the images seen by the amblyopic eye. This is almost always a unilateral problem but may manifest with reduction of vision in both eyes. It is estimated that up to five percent of the children under six have some form of amblyopia.
The exact cause is still unknown other than the brain will disregard the image from one eye. Normally the images sent by each eye to the brain are identical. When they are different the brain will inhibit the visual pathway from one of the eyes one image and prefer the other. This is a result of double vision as in strabismus (eye turn) or due to blurred images from large enough difference in the degree of (refraction) nearsightedness, farsightedness or astigmatism between the two eyes. As these developmental conditions usually occur as infants, amblyopia is generally the result of poor early visual development. Certain nutritional and chemical factors can play a role also.
Since amblyopia usually occurs in one eye only, many children may be unaware of the condition. It is often first identified at preschool and pediatrician screenings although an effective screening is difficult with young children. This allows many students to sneak by until they have their eyes examined at the eye doctors office. A parent, teacher or school nurse may notice the child favoring one eye. The most important diagnostic tools are the special visual acuity tests other than the standard letter charts used by the pediatric optometrist. With them, children as young as six months can accurately be evaluated to rule out amblyopia. The doctor will ask a detailed history and should dilate the eyes to make sure that there is no hidden eye disease masquerading as amblyopia.
For many years, it was thought that amblyopia was only treatable during the “Critical Period.” This is the period up to age seven years. Current research shows that effective treatment can occur at any age and therefore age is not a restriction for treatment. The limiting factor remains that the length of time the amblyopia is not treated increases the eventual treatment duration. In most cases, eyeglasses, prisms, contact lenses and/or vision therapy (eye-exercises) are used in the treatment regimen. Active vision therapy has been shown to be the most effective way to manage amblyopia. In some cases, patching the good eye stimulates and strengthens the amblyopic eye when accompanied by vision therapy.
Whether it is strabismic or refractive, amblyopia always requires appropriate evaluation and treatment. When diagnosed and treated early the prognosis is excellent. Regular visits to your family optometrist will ensure a lifetime of healthy eyes and good vision.