Pediatric Ophthalmology is a subspecialty of Ophthalmology dealing with problems common to, or seen exclusively in, the pediatric age group.

Why is the pediatric eye different from that of an adult?

The brain cells that control our vision are not fully developed, or mature, when we are born. These cells develop throughout the first decade of life. Because of the immaturity of the child's visual system, disorders that may have little effect on an adult’s ability to see can have a profound and life-long effect on a child's vision. Poor vision due to inadequate stimulation of these brain cells, amblyopia, is a common cause of loss of vision in this age group.

What is a Pediatric Ophthalmologist?

A pediatric ophthalmologist is a medical doctor who was first trained in diseases and surgery of the eye after finishing medical school. They then pursue further training in the diagnosis, treatment and surgery of those eye disorders that are unique to children.

Problems Seen in the Pediatric Age Group

Some disorders are only seen in children. Some disorders, such as certain types of tumors, may be found in both children and adults, but may have different effects when they occur in children, i.e. cataracts.

The Pediatric Eye Examination

This is what you can expect to have done during the course of your child's eye exam:

• Visual Acuity
  Your child's vision will be checked. This is possible even in children who do not speak yet. For older children, picture charts, letter games and letter recognition can be used.
  
  
• Eye Alignment (Muscle Balance)
  Various methods are used to test the alignment of the eyes and make sure the muscles, which move the eye, are functioning normally. This may be done using light reflexes or alternately covering each eye to make sure that they do not move from the straight ahead position.
  
  
• Binocular Vision
  These tests are used to make sure that the eyes are not only aligned correctly, but that the brain is using them together as well. If the eyes are properly aligned, it does not always follow that the brain is using them together.  Proper eye alignment is important for the development of depth perception, or the ability to see objects in 3D.
  
  
• Refraction
  A refraction is used to measure the "power" of the eye. It determines if your child is nearsighted, farsighted or has an astigmatism.  This can be done in infants where they cannot cooperate to tell us how well they are seeing. A special light is placed into their eyes and the light is moved back and forth. The light enters the eye and "bounces" back to the examiner. The way the light behaves as it comes back out through the child's eye can be used to determine the refractive power of the eye. To obtain accurate measurements in young children, the focusing power of the eye must first be neutralized. This is done by placing drops into the eye to dilate the pupil and eliminate their focus mechanism. These drops often take 30-60 minutes to work.
  
  
• Fundus Examination
  The examiner uses a special light, often worn on his/her head, to look into the back of your child's eye. The retinal blood vessels and the optic nerve, an extension of the brain, can be seen. Because this is an area where blood vessels and portions of the brain can be seen, it is very valuable in helping to diagnose many disorders that can affect the entire body.

Once the examination is complete, your child may be prescribed glasses. Treatment for other problems may also be addressed. If your child received drops, he/she may experience blurry vision until their effect has resolved (anywhere from three to 24 hours). The duration of this effect is dependent on the type of drop used, the color of his/her eyes and the refractive power of the eyes.

What is Strabismus?

Strabismus is a misalignment of the eyes. It includes in-turned eyes (esotropia), out-turned eyes (exotropia) and other eye muscle disorders. Because strabismus is treated so often by pediatric ophthalmologists, many pediatric ophthalmologists also treat adults with strabismus.  When strabismus occurs in an adult for the first time, it can lead to double vision, or diplopia.

Causes of Strabismus in an Adult

The following are the most common causes of strabismus in adults:

Strabismus in an adult who had a history of strabismus as a child. Many children are successfully treated for strabismus only to redevelop strabismus later in life. This may be secondary to the inability of a person to use both eyes together (binocular vision) or other unknown causes.

Poor vision in one eye. People who have one eye that does not see well when fully corrected with glasses may develop strabismus with time. Most often, the poorer seeing eye drifts outward.

Vascular insults to a nerve that controls the movement of one or more eye muscles can lead to strabismus. This is most often seen in adults with a history of diabetes or high blood pressure.

Treatment of Strabismus in Adults

Treatment of strabismus in an adult depends on the cause of the strabismus. Small deviations that cause double vision can often be treated with prism glasses. These glasses do not "cure" the problem. They "compensate" for it by adjusting the rays of light that enter the eye in order to eliminate double vision. Only a relatively small strabismus can be treated in this way since prism glasses may distort vision and can be very thick.

Most strabismus caused by vascular insults get better with time. Therefore, the treatment for this form of strabismus is often watchful waiting. Patching one eye, or the use of prism glasses, may eliminate the bothersome double vision until time has allowed the problem to correct itself.

Patients with a history of strabismus, poor vision in one eye that has lead to the development of strabismus, unresolved strabismus from a vascular insult and a large angle strabismus may be helped with strabismus surgery.

Summary: Adult strabismus is common and has a number of causes. Most adult patients can be helped with a variety of treatment modalities. 

Causes of Strabismus in Children

• Congenital Esotropia
  This form of esotropia (crossed eyes) is also known as infantile esotropia.  It usually develops before the child is six months old and is characterized by a large eye turn.  Unlike accommodative esotropia these children are normally farsighted for their age and glasses will not correct the eye turn.
  Amblyopia is common in children with congenital esotropia and should be treated early. Once the child's vision is equalized, treatment can be recommended for the eye turn. Eye muscle surgery is the treatment for patients with infantile esotropia. The surgery is usually on both eyes, although it may also be done on one eye.   The goal of treatment is infantile esotropia is to straighten the eyes so that the child can learn to use them together, develop "binocular vision. The ability to use both eyes together will help to keep them aligned.
  Studies have shown that early surgical alignment improves the chances of developing binocular vision. Therefore, many pediatric ophthalmologists recommend surgery when the angle of crossing is stable and the vision in each eye is good.
  
  Other disorders associated with Congenital Esotropia
  
  Many children with congenital esotropia develop other eye muscle disorders. This occurs even when their eyes have been made successfully straight with surgery. Recurrent esotropia following surgery for congenital esotropia occurs in about 25% of patients. Most, about 75%, can be treated with glasses and do not require further surgery. This is a different type of esotropia than the original infantile crossing. Up to 75% of patients develop overacting Inferior Oblique Muscles or Dissociated Vertical Deviations. These can occur months to years after the original surgery.  Treatment may require surgery.
  
  In conclusion, infantile esotropia is a complex disorder. Although surgery is required to treat it, it is only the start of the process. These children must be carefully followed for other problems during the visually immature period of their life.
  
  
• Accommodative Esotropia
  Most children are farsighted. In children, this means that they have the potential to see well at both distance and at near. However, they have to "focus" or accommodate to do so. This is usually not a problem as children have a large "focusing" ability. A reflex exists that makes the eyes want to cross when we try to focus. This normal reflex allows our eyes to maintain alignment when we focus to read material close to us, i.e. our eyes must both turn in a little to work together at near. However, if a child is very farsighted, their eyes will cross when they focus to see well. In this case, they must make a subconscious decision to see well or cross their eyes. The treatment for this type of strabismus is glasses. The child is given glasses to correct their farsightedness. Because they no longer have to focus to see well, they will no longer cross their eyes. Amblyopia is very common in this setting. If amblyopia is present, treatment for this, in addition to the glasses, may be required. Many children lose some of their farsightedness as they get older and will outgrow their glasses. This is dependent on the initial level of farsightedness and the growth curve of the eye. It is very individualized and therefore it is hard to predict who will outgrow their need for glasses.
  
  
• Intermittent Exotropia
  Intermittent Exotropia is a strabismic disorder when one, or both, eyes turn outward (exotropia) intermittently. It usually begins in the 2-3 year age group. It is first seen infrequently when the child is sick or tired and only when they are looking into the distance. For this reason, in its early stages, it may not be seen in a pediatrician's office, when the child is examined only up close and is well rested.  It generally progresses in frequency and duration with the eye turn occurring earlier in the day and the deviating eye staying out for longer periods of time. Often, the child closes one eye to eliminate the double vision that it may cause. This is especially noticeable in sunlight. As the disorder progresses, the eyes will also start to turn out when looking at close objects as well, i.e. reading. If not treated, the eye may turn out constantly and binocular vision could be lost. Amblyopia can occur in intermittent exotropia but is uncommon.
  
  Treatment is usually required when the deviation is noted to be progressing. Various treatments may be offered depending on the frequency and size of the deviation as well as the age of the child.
  
  

Amblyopia

Amblyopia is the medical term for poor vision in one, or sometimes both eyes. Children are born with poor vision.  As they develop the eyes send the message of what they see to the brain and the visual brain cells “learn” how to interpret these images.  Over time the brain learns how to fine-tune the images it is receiving and the vision improves.  If the image that is being sent to the brain is blurry then the brain will never learn how to see clearly from that eye.  The important piece in this problem is that the brain cannot “learn” how to see clearly after a certain age (that age is not known for certain).  We do know that the younger the patient is when he/she is treated the better the outcome will be.  So, amblyopia should be treated as early as possible.

Causes of Amblyopia

The most common forms of amblyopia are strabismic and anisometropic. Strabismic amblyopia occurs when a strabismus is present and the eyes are not aligned. The brain favors one eye over the other and the non-preferred eye is not adequately stimulated and the visual brain cells do not mature normally. Anisometropia refers to the condition when the eyes have an unequal "refractive power". As an example, one eye may be nearsighted and the other farsighted. Because the brain cannot "balance" this difference, it picks the eye that is "easier" to use and develops a preference for this eye only. Other causes of amblyopia include: cataracts, ptosis and trauma.

Treatment of Amblyopia

In most cases amblyopia is treatable. However, the success of treatment is dependent upon the initial level of vision, the amount of time the vision has been poor and the age of the child. The most important factor in treating amblyopia is compliance with the treatment protocol. Treatment requires "forcing" the brain to use the non-preferred eye. In most cases this means patching the better seeing eye for some part of the day. Glasses may also be required to "balance" an unequal refractive power between the two eyes. For some patients a drop can be used to blur the vision in the better seeing eye.  If a cataract is present, this may need to be removed before amblyopia treatment can be started. The initial treatment period may be difficult for the child, as he/she is being made to use their poorer seeing  eye. This usually lasts a short period of time, as their vision usually improves rapidly.

Prognosis of Children with Amblyopia

The prognosis for kids with amblyopia is quite good- if treatment is properly performed.  It cannot be overemphasized that the major reason for failure in the treatment of amblyopia is poor compliance with the treatment protocol. Remember, amblyopia can be treated only when a child is young. If it is delayed until the child is older and more understanding, it may be too late!

Pediatric Cataracts

A cataract is an opacification (clouding) of the normal lens.  Cataracts can occur at different ages in children.  The diagnosis of a congenital cataract (present at birth) can be made on the first day of life if a red reflex is not obtained in the newborn nursery. Early diagnosis and referral are important since irreversible damage can occur if a congenital cataract is not treated in the first few months of life.

Causes of Cataracts

Cataracts can result from problems with the eye itself or from systemic disorders.  Because of this a thorough ocular and systemic evaluation should be performed in any child who presents with a cataract. A genetic evaluation may be indicated in some cases as well.

Treatment of Cataracts

If the cataract is determined to be visually significant, surgery is indicated to remove the involved lens. Once the visual axis is cleared, the child will require optical correction to allow visual rehabilitation. This may include the use of glasses, a contact lens or an intraocular lens implant. Because of the small size of the infant eye, a high power optical correction is necessary, which often cannot be obtained by the use of glasses alone.

Glasses may also not be appropriate in a child following unilateral cataract extraction because of their magnification effect.  This can result in difficulty with clarity of vision as well as  problems with the development of binocular vision.  Because of these factors a contact lens is sometimes used.  These contact lenses should not be thought of as a substitute for glasses as they may be in adult patients. They are an absolute necessity for infants with cataracts or an older child with a unilateral cataract. In some patients an intraocular lens can be implanted. Because of concerns regarding the immaturity and future growth of the infant eye, some surgeons prefer not to implant an intraocular lens in a very young child.

Prognosis of Children with Cataracts

Children with bilateral cataracts tend to do better than those with unilateral cataracts. Amblyopia is a major obstacle to the development of good vision in these children. Amblyopia therapy is an important issue in the management of childhood cataracts. A good visual outcome is highly dependent on the compliance with amblyopia treatment. Other complications that can develop at any time following cataract surgery include retinal detachment and glaucoma.

Retinopathy of Prematurity

Retinopathy of Prematurity (ROP) describes problems with the development of the blood vessels in the retina in preterm infants.  ROP describes a spectrum of problems from minimal changes to the periphery of the retina to uncontrolled growth of blood vessels centrally.

Causes of ROP

ROP occurs almost exclusively in preterm infants. Retinal blood vessels begin developing at 16 weeks of gestation and are not fully developed until 40 weeks of gestation.  In infants born prematurely the blood vessels can grow irregularly.  These changes can be transient with small changes to the periphery of the retina only.  However, they can also involve uncontrolled growth of blood vessels which in the most severe cases can cause a detachment of the whole retina.

The risk factors associated with ROP are not fully known, but prematurity and low birth weight are major factors.  Problems such as respiratory distress, bradycardia (low heart rate), heart disease, infection, hypoxia (low oxygen levels), anemia, and the need for blood transfusion are other risk factors. Generally, the lower the birth weight and the more medical problems with the infant, the greater the risk for ROP.

Treatment of ROP

In some cases ROP will need to be treated.  This is done using laser or cryo (a freezing treatment) therapy.  In severe cases, surgery to correct a retinal detachment can be required.

Prognosis of Children with ROP

In more than 90% of infants with ROP there is spontaneous regression of the disease process, with little or no residual effects or visual disability. In less than 10% of infants there is progression toward severe disease.  Despite treatment some of these cases can lead to detachment of the retina, and impairment of vision. Over the course of their lifetime children with ROP are at increased risk for strabismus, amblyopia, nystagmus and refractive errors.

Learning Disabilities

In general, learning disabilities are a problem of processing and understanding verbal and written language.  Dyslexia is one example of such a disability.  Keep in mind that these learning disabilities are not a problem of intelligence.  It is important to recognize their presence and help children learn to deal with the disability.  Also, do not forget to continue to provide support and encouragement to your child remembering to emphasize the areas where he/she excels.

Causes of Learning Disabilities

Causes of learning disabilities are not fully understood.  There is probably a genetic component so they can run in families.  There is no good evidence that suggests that learning difficulties are related to a child’s vision or visual system. 

Treatment of Learning Disabilities

Treatment requires a multidisciplinary approach.  Educators, psychologists and physicians should all be involved.  A pediatric ophthalmologist will test the eyes to ensure that there are no refractive errors, strabismus, eye movement problems, or problems with focusing and convergence of the eyes.  Once these areas have been addressed emphasis should be placed on a solid academic program of working to improve your child’s areas of weakness.

Double Vision

What causes Double Vision?

Diplopia, the medical term for double vision, can be caused by a number of disorders. Diplopia can be monocular or binocular.

Monocular diplopia does not go away when either eye is closed. This type of diplopia can be caused by defects in the front part of the eye, cataracts or the need for glasses.

Binocular diplopia does go away when either eye is closed. This type of diplopia can be caused by a misalignment of the eyes which can be secondary to many disorders. A new onset of binocular diplopia should be brought to the attention of your doctor promptly.

There are different ways diplopia can be treated and these include: patching, glasses with prisms and surgery.

Nasolacrimal Duct Disorders

Tearing in children is a common finding.  There are many different causes of tearing and it is important to have your doctor check your child for some of the more serious problems.  Most often tearing is caused by a blockage of the nasal lacrimal duct (NLD) passageway.  This is a common finding in infants- studies have shown that about 6% of infants are born with a NLD obstruction.

Causes of Nasal Lacrimal Duct Obstructions

The most common cause of an obstruction is from a mucous membrane of the nose which fails to regress during development.  Other causes of NLD obstructions include irregular development of the lacrimal drainage passageway,  infections, trauma, growths and medications.

Treatment

Treatment initially involves massaging the lacrimal system, warm compresses and sometimes antibiotic drops.  If these interventions are unsuccessful, a nasal lacrimal duct probing may be necessary.  At times this procedure can be performed in the office and at times in the operating room.  Some children require the placement of a silicone tube in the nasal lacrimal duct system to keep the passageway open.  This tube remains in place for 6-12 months and can usually be removed in the office.  If this is unsuccessful a balloon cather can be used to dilate the lacrimal system in addition to the silicone tube placement.

Outcome

Most obstructions will resolve on their own by one year of age.  However, some children have severe symptoms and require intervention before this age.  Studies have shown that probing the system is most successful if performed prior to one year of age.  The next most successful group of patients is those undergoing a probing by 2 years of age.  Probing in kids over 2 years of age is also successful but less so than if performed at a younger age.