All About Amblyopia (Lazy Eye)

Amblyopia is a vision development disorder when one eye has better vision than the other. The brain prefers the eye with the better vision so the weaker eye gets worse. For this reason, amblyopia is commonly referred to as “lazy eye” due to one eye having a significantly lower quality of vision than the other. In normal cases, the brain receives an equal amount of visual stimulation from each eye, allowing the brain to develop a proper connection and understanding with the eyes. When the brain receives considerably less visual stimulation from one eye, it will have a difficult time developing a connection and visual development in this eye can be severely impaired.

Visual development begins at birth but the most critical times are considered to be between 6 months to 3 years old. Since most children in this age range have a difficult time expressing visual imperfections, it is up to the parents or primary care physician of the child to monitor visual development during this critical time.

Symptoms

• Misaligned eyes
• Double vision
• Poor depth perception
• Head tilting
• Squinting or shutting one eye

Common Types of Amblyopia

• Refractive Amblyopia: Uncorrected refractive errors are the most common type of amblyopia. An abnormality in the structure of one eye causes light to focus in front of or behind the cornea, which leads to blurred or distorted vision. Having one eye with a significant refractive error can lead to the development of amblyopia.
• Strabismus Amblyopia: This type results from a misalignment of the eyes. One eye might turn upward, downward, inward or outward while the other stronger eye looks straight ahead. When the eyes are misaligned, the brain receives two different images. The brain prefers the image from the stronger eye, leading to a loss in visual acuity and depth perception in the misaligned eye. According to the American Academy of Opthalmology, roughly 4% of children in U.S. have strabismus.
• Deprivation Amblyopia: This is the least common and most severe type of amblyopia that happens when one eye is deprived of visual signals. Some common causes of visual deprivation are congenital cataracts or eyelid ptosis, also known as a droopy eyelid.

Amblyopia Treatments

• Prescription Eyeglasses: Glasses may be prescribed to help with eye alignment and increasing visual acuity along with treating common refractive errors.
• Vision Therapy: Patching and other types of vision therapy are often the first steps toward vision correction. Since amblyopia refers to the brain's decision to show preference to a “good” eye and ignore the bad eye, patching the good eye forces the brain to strengthen the other eye. Not always a popular choice with children due to the complete blocking of visual stimulation from the good eye, patching for 1-2 hours a day provides the 1-on-1 the brain needs with the amblyopic eye.
• Intentional Blurring: This treatment is when you blur the good eye using dilation drops or a Bangerter filter, which forces the brain to allocate attention to the amblyopic eye.
• Surgery: A surgical procedure is applicable to specific types of amblyopia and is an option an ophthalmologist may consider to remove congenital cataracts or to correct strabismus (misaligned eyes). It is common for ophthalmologists to postpone surgery until other treatment methods have been explored and progress has been made to strengthen the visual development of the amblyopic eye.

Treatment Effectiveness

If diagnosed early enough, and depending on the patient’s root cause of amblyopia, it is possible to treat and continue with acceptable visual development. Adults over the age of 18 can also see positive results from amblyopia treatments but in order to have the highest success rate, diagnosis and treatment of amblyopia should happen before the age of 9. As always, if you have any concerns about your child’s visual development, schedule a comprehensive eye exam with a pediatric ophthalmologist.