Amblyopia and strabismus are two of the most common diagnoses encountered in pediatric ophthalmology. Many children may not have been diagnosed with either condition or they may have one of the conditions and do not know that treatment can be performed.
Amblyopia is the most common cause of vision loss in children. It is due to the brain not learning to use one or both eyes, and as a result, there is decreased vision.
This decrease in vision can be extremely mild or can be to the point that the child can only identify light from that eye. Amblyopia has many causes which include: high refractive errors, significant difference in refractive error between eyes, strabismus, cataracts, corneal opacities, ptosis of eyelid from numerous causes. Some causes can be easily seen such as a white cataract or eyelid drooping and blocking the eye. Other causes such as anisometropia cannot be seen at all.
Anisometropia and high refractive errors can cause amblyopia. Anisometropia means there is a significant difference in refractions between both eyes. One eye may have significant astigmatism, myopia or hyperopia compared to the other eye.
This can be a diagnosis that can be missed because if there is no strabismus, the child will usually not demonstrate any noticeable problems to the parents. If they are seeing well from their other eye, the child will not usually complain about anything. This is how pediatricians, family practice doctors and schools can help. They screen children to see if one eye is seeing worse than the other, and if this is noted, they are sent to an eye care professional to evaluate.
Identifying amblyopia earlier is crucial. With early detection, treatment can begin which allows better vision to be obtained. The treatment of amblyopia consists of getting the image from the eyes in best focus on the retina and then forcing the brain to use the eye. Getting an eye in focus may consist of doing something as difficult as cataract surgery to something as simple as placing the child in glasses. A child with anisometropic amblyopia that is identified early can end up with 20/20 vision in both eyes by just being placed in glasses at an early age. If these children are missed and not identified, they could possibly be blind in that eye for the rest of their lives.
The first treatment of amblyopia is getting the image in focus to the retina. Sometimes this is all that is needed. Other times, more treatment than just glasses are needed. If glasses alone do not or will not improve the vision, then the child may be required to patch the better seeing eye part of the day to force the brain to use the eye seeing worse. Other options than patching include using atropine 1 percent in the better-seeing eye to dilate it and blur it to force the brain to use the other eye. Another option is placing a Bangerter foil on the glasses that makes it darker and blurs the vision in the better-seeing eye. Another treatment that is being studied at this time is called dichoptic treatment. This consists of playing video games or watching videos in which special glasses are worn to cause one eye to be used more than the other.
All treatment is continued until vision is improved to as close to 20/20 in both eyes. Once reached, the treatment is tapered over time usually, instead of stopping all at once. The reason for this is that there can be a recurrence in the amblyopia, and vision can decrease again. This is also why it is important to continue to follow these children even when vision improves to make sure that it stays improved. Usually when a child reaches 8-10 years of age, the vision will remain stable.
There are still children that are not diagnosed until much later, even into their teens. These children still need treatment, because up to 25 percent of the older children can still have improvement in vision with treatment, whereas, if they are diagnosed by 3-5 years of age, about 90 percent will have response to treatment. This is why children need to be diagnosed as soon as possible.
Strabismus is when a child’s eye does not line up correctly. This includes crossing of eyes, turning out of eyes, or one eye being higher than the other eye. Strabismus can be seen at any age from birth and into all ages of adults. At a young age, treatment is important because it can prevent amblyopia or help treat amblyopia. It can also allow the child to be able to use both eyes together and have stereo acuity.
Many babies will have some degree of strabismus. This should resolve by 4 months of age. If it has not, the child should be sent for an eye exam. This eye exam may show strabismus only and require surgery to repair. It may show that the child has amblyopia that needs to be treated. If he or she still has significant strabismus after amblyopia treatment, they may then require surgery. Exam may show a well-controlled, mild deviation that requires observation only. Exam may also show an underlying disease such as retinoblastoma of the eye that requires immediate treatment to try to save the eye and prevent further spread of the tumor. Sending this child for an eye exam may be lifesaving. Other abnormalities in the retina causing decreased vision and strabismus may lead to diagnosis of systemic diseases.
Strabismus developing later also needs to be sent to the eye care professional. A common form of childhood strabismus is an accommodative esotropia. This is crossing of the eyes that start at 2-4 years of age. The treatment for this disease is placing the child in glasses to treat their hyperopia. Children and adolescents can also develop crossing of eyes that is non-accommodative that is due to abnormal connections from the brain to the eyes that require surgery on the eye muscles to correct. There are other forms of crossing that are due to congenital abnormalities of muscles or other forms of crossing that can be due to increased pressure on the brain or a brain tumor which require neurosurgical intervention. No matter what the cause, the child needs to be evaluated. It is not something to watch and hope that gets better.
Other forms of strabismus commonly encountered include exotropia. This is a turning out of the eyes. It can be mild and well controlled and require observation only. It can worsen and require strabismus surgery to correct. It can be related to poor vision in one eye that may improve if the vision can be improved. Other forms of strabismus can also cause abnormal head postures. This includes a superior oblique palsy or fourth nerve palsy. The superior oblique muscle does not work correctly and causes that eye to be higher than the opposite eye. The child will often tilt his or her head to the opposite side, which helps straightens the eyes out. Any child with an abnormal head posture should be evaluated for strabismus. Correction of the strabismus can then correct the abnormal head posture.
These were just a few common types of strabismus noted. There are numerous other types that cannot be covered in one article. Whatever type is encountered, the child should be sent for evaluation. This can make a huge difference in the child’s vision and life.
Amblyopia and strabismus are two common disorders encountered in children. Children need to be evaluated as soon as the disorder is suspected. Early diagnosis and treatment can lead to a lifetime of improved vision and self-esteem for the child.
Dr. John D. Hinrichsen is a pediatric ophthalmologist / strabisumus specialist at Highland Clinic who devotes his practice towards the diagnosis and treatment of eye problems in children. He specializes in the treatment of strabismus, amblyopia, ptosis and nystagmus. He can be reached at 222-8402, at his office at 1455 East Bert Kouns Industrial Loop, Suite 103. He also sees patients at the Louisiana Eye & Laser Pineville office. To schedule an appointment, call 1-800-437-0153 or visit the Web site www.highlandclinic.com/staff/johnhinrichsen-md.