Lazy eye or amblyopia, is the #1 cause of preventable and reversible blindness in children. Amblyopia can be caused by a variety of eye conditions, but the most common reasons why a child develops amblyopia is due to eye teaming failure (strabismus) or significant unequal refractive error between the two eyes. In either case, the reason behind the cause of amblyopia is due to an interference with the vision from each eye reaching the brain. Since humans are not born with 20/20 acuity, good vision must gradually develop naturally during infancy and toddler-hood. However, if something gets in the way of that normal sight development, then the result can be poor vision in one eye...amblyopia.
One interesting fact is that amblyopia is a diagnosis that is universally understood among eye care professionals as a condition that responds to vision therapy. The most common form of vision therapy for amblyopia is patching or occlusion therapy. Yes, patching therapy is an example of a "passive" form of vision therapy! The rational behind using occlusion therapy is that by patching the "good eye" you "force" the amblyopic eye to begin to do the work of seeing. So, occlusion therapy is the most universally accepted form of vision therapy in the eye care community. However, patching has many limitations as a stand alone treatment.
Patching can be accomplished with using a "black patch" to occlude the "good" eye or it can be in the form of a bandage that tapes over the good eye so that the child can not peek around the eye-wear frame. Patching can also be done pharmacologically, ie with a special eye drop called Atropine that will temporarily prevent the good eye from focusing by interfering with the focusing muscle of the eye.
But, it is important to know that "stand alone" occlusion therapy can bring about other signficant problems. First it is important to understand that when you cover up one eye in a child who does not see clearly in the other eye, that alone is very disruptive to that child's spatial orientation, motor development and coordination. To find out for your self put on someone else's glasses that results in you experiencing blurred vision and then cover one eye and walk around your house. How does that feel? Now imagine you are a young child and just learning how to coordinate you body and learn in the classroom and now you must wear a cover on your good eye. Do you think you would be very happy?
The second problem with patching is that it reinforces the child to be a one-eyed person. In other words, occlusion therapy does not teach a patient with strabismus how to see with two eyes since it reinforces the use of only one eye.
Third, using patching therapy alone is the equivalent of having only 1 tool in a tool box to build a house.
For example, if you set out to build a house and the only tool you had in your tool box was a hammer, then you most likely would only be able to hit nails. What type of house would you be able to build with just a hammer and nails?? A house that was not very well built or functional.
The same is true in when working with a patient with amblyopia. While occlusion therapy has been prescribed by optometrists and ophthalmologists for over 100 years in the treatment and management of amblyopia, as a stand alone treatment it often leaves the patient with an incompletely developed visual system where there is a lack of "two-eyed" vision and poor or no depth perception.
While there is a place for occlusion in the treatment of amblyopia, it is a passive form of treatment and it must be judiciously prescribed and monitored. But, most importantly, the child with amblyopia represents a patient with a complex binocular vision problem that requires more than the limitations of patching the "good eye"!
Active office based vision therapy guided by the doctor and vision therapist (in conjunction with appropriate lenses, prisms and when appropriate occlusion) is the proven treatment for children with amblyopia in the 21st century. Active vision therapy builds binocular vision, depth perception and function of the visual system. This is the "glue" to maintain your child's vision after treatment.
If your child has been diagnosed with amblyopia don't settle for a treatment plan that involves just an eye patch, just like you would not expect the builder of your home to have only a hammer as the only tool in his tool box.
Your child's doctor may begin with the judicious application of occlusion treatment as a starting point, for possibly a couple hours per day for a few weeks and monitor your child's progress. It will also be important for you to ask your doctor if he or she doesn't mention it in the beginning, who they would recommend your child to see for vision therapy to help with development of their binocular vision. It could make a difference that will affect their entire life.
Good binocular vision (with depth perception) means success for the patient recovering from amblyopia. That is what active vision therapy brings to child with amblyopia. A whole toolbox full of tools to build a complete and functional "visual home".
Dan L. Fortenbacher, O.D.,FCOVD
