Amblyopia or Lazy Eye

Amblyopia (or lazy eye) is a functional loss of vision in one eye with a best corrected vision of 20/30 or worse. However it can be bilateral in some rare instances. It has been estimated to affect 1-5% of the population. There is a critical period of development of the visual system in humans from birth to two years where there needs to be a sharp focus on the retina of the eye. The affected eye is typically deprived of clear vision during this time. This in turn prevents the information processing channels of the retina, optic nerve tracts and the visual cortex of the brain to develop to their fullest potential. The abnormal eye sends a blurred image to the brain. The brain learns to ignore the image from the weaker eye and actively suppresses it. If both eyes fail to receive clear images, amblyopia may develop in both eyes. Amblyopia causes more visual loss in the under 40 age group than all other categories of disease combined.

• Eyes that do not appear to work together
• Eyes that turn in or out
• Inability to judge depth correctly
• Poor vision in one or both eyes
• noticeably favoring one eye
• tendency to bump into things on one side

Symptoms are not always apparent.

Ambyopia can be caused by the deprivation of vision in early life by congenital cataracts, by strabismus (misaligned eyes), anisometropia (differing amounts of myopia or hyperopia in each eye), or by significant amounts of astigmatism in one or both eyes. It can be psychogenic in nature as in hysterical amblyopia.

Strabismus (eye turning in or out) is the most common cause of amblyopia. Many use the term "lazy eye" imprecisely to refer to an eye turn but this is not correct. Eye turns (strabismus) can occur without amblyopia. Amblyopia can occur without strabismus.

Refractive or anisometropic amblyopia results when there are unequal refractive errors between the two eyes. These differences must be rather large to cause problems. The eye with the larger refractive error will be suppressed resulting in amblyopia.

Organic abmblyopia will develop when something physically blocks the vision of the eye such as a congenital cataract. Other causes are corneal disease, nutritional, and toxic such as methyl alcohol poisoning.

A complete eye examination can easily diagnose this condition. Detecting this condition in early childhood increases the probability of recovering the vision in the affected eye especially if detected before age 5. The earlier the detection and correction through glasses, contact lenses or surgery, the better the chances of improving the vision of the affected eye.

Treatment consists of correcting any refractive error present with glasses, contact lenses, and patching therapy. In patching therapy, the good eye is patched forcing the brain to use the amblyopic eye. Depending on the patient, patching could be constant or for as little as 3 hours per day. Some sort of nearpoint activity helps the therapy such as coloring or drawing. Eye patches that adhere to the skin around the eye are most effective in young children but sometimes pirate patches are used in older kids. Sometimes the good eye is pharmacologically blurred out so that patient is not stigmatized by wearing a patch. Some recent studies indicate that l-dopa prescription meds speeds the improvement of vision in patching therapy by 30%. Some research from China reports the benefits of acupuncture in amblyopia therapy.

If strabismus is present then surgery is indicated to align the eyes. A congenital cataract may necessitate cataract surgery in the infant. There is a nice video about strabismus surgery below.

The earlier the intervention the better, and ideally before age 8. The older the child, the poorer the prognosis for recovering useful vision in the affected eye. Certainly poor vision can affect school performance and subsequently career opportunities. There is a high correlation between poor vision in school and juvenile delinquency .

From birth to ages 6 to 8, the visual system is undergoing rapid development and is susceptible to amblyopia. This amblyopia can be a result of refractive errors, misalignment of the eyes and cataract. Prognosis for functional vision is very good with early detection and treatment. Please have your childrens' eyes examined at an early age.