Pediatric Prescription Analysis

By Katheryn Dabbs Schramm, FNAO, ABOC

LASTING EFFECTS

Adult spectacle prescriptions are relatively straightforward and the refractive error associated with the Rx is easily determined. Adult prescriptions either protect the eye from the environment, make the wearer see better while using the glasses, or both. The eyewear functions as a temporary vision-aid, only benefiting the wearer while being worn. Wearing or not wearing the glasses does not change the patient’s refractive error. However, glasses may help a child in other ways and the prescription presented is not always indicative of the primary condition being treated. Early childhood is one of the only times glasses may be prescribed for therapeutic value that may benefit the child for a lifetime.

DIFFERENT PURPOSES

While adult and pediatric spectacle prescriptions look identical, their purposes may be quite different. When an adult is prescribed +2.00 diopter lenses, the patient is assumed to be hyperopic. The same Rx prescribed for reading suggests presbyopia. In both cases, the Rx is written to enable the wearer to see 20/20 or as close to 20/20 as possible while wearing the glasses. However, a +2.00 diopter lens prescribed for a young child may or may not indicate hyperopia and the goal of treatment may not be to correct the child to 20/20, as 20/20 may not be normal or beneficial. Since the Rx presented is not necessarily indicative of the primary condition being treated, the dispenser must consider more than just the power prescribed.

Effective pediatric prescription analysis is based on the child’s age and stage of visual development, the most common conditions encountered within that age group, the prescription and information obtained from the parents.

WHY IS THIS IMPORTANT?

Early diagnosis and treatment of vision problems can be vital to the healthy development of a child’s visual system. A knowledgeable pediatric optician can significantly aid the success of that treatment. It is not enough to produce glasses that fit the child correctly and only meet or exceed ANSI standards. The best eyewear is of no benefit if it is not worn properly.

COMPLIANCE

Compliance simply means getting the child to wear his or her glasses as prescribed. If the dispenser does not understand the importance of the prescription, the parents will not understand the importance of the eyewear. No loving parent will establish the routine or exert the discipline required to gain compliance without understanding the risks of non-compliance. While the doctor may have explained the diagnosis, often parents are too emotional or distracted to fully comprehend. It is up to the pediatric optician to get enough information from the parents to see that the glasses are worn as the doctor intended.

A CHILD’S VISUAL SYSTEM

The eyes are present by the fourth week after conception. Vision actually begins at birth and develops rapidly thereafter. Newborns can distinguish contrasting colors and moving patterns and may respond to the mother’s face. Clear focusing begins by six weeks of age and fully matures around four months. This is the age when it is no longer normal for a child’s eyes to “wander” or “cross.”

The lens of the eye is critical to refractive development, second only to axial length (length of the eye). The average lens will undergo a 20-diopter change in power and will change in curvature from infancy through childhood. The cornea will undergo approximately a 5-diopter change in power and be fully developed by the age of two years.

The most critical period for development of the visual system is from birth to age three years and tremendous changes continue through age seven.

Visual maturity, while unique to each individual, generally occurs between ages eight and 10. Prior to this age, the visual process is malleable. However, after the visual system has matured, improvement is unlikely.

Early detection of vision problems can help minimize visual dysfunction and allow normal development of binocular vision and depth perception. Childhood represents the only time when treatment can have a positive and lasting effect on visual outcome.

REFRACTIVE ERRORS

Although refractive errors occur in approximately 15 to 30 percent of young children, modest, symmetric refractive errors generally do not require correction. Children with more severe refractive errors usually are prescribed glasses for full-time use to improve visual acuity, prevent amblyopia, increase learning efficiency or enhance binocularity.

Myopia—Premature and low birth-weight infants tend to be more nearsighted (myopic) than full-term, normal birth-weight infants. Approximately 45 percent of premature infants are myopic compared to 20 percent of full-term infants. Myopic children commonly are prescribed glasses based on their age and amount of myopia present. Younger children seldom are prescribed myopic corrections with less than 3 diopters of power. Minus lenses also may be prescribed to treat exotropia (eyes turn out) a less common condition.

Hyperopia—The normal eye at birth, due to its size and shape, is farsighted (hyperopic). As the visual system matures, the eye becomes longer in shape and less farsighted. Children with greater than 1.50 diopters of hyperopia at age five years tend to remain hyperopic. Frequently, plus lenses are used to treat esotropia (eyes turn in).

Astigmatism—Astigmatism results from an irregularly shaped cornea or lens. Approximately 50 percent of normal, full-term babies are likely to be astigmatic, which decreases after the age of 18 months, but still may be present in large amounts at age three.

Anisometropia—Commonly used to indicate a considerable difference in the refractive error of the two eyes, anisometropia may suggest amblyopia. Between 11 and 22 percent of normal, full-term babies are anisometropic. Approximately 32 percent of myopic preemies are anisometropic.

COMMON CONDITIONS

Listed below are some common conditions that may be easily illustrated in the patient’s chart with simple hand drawn diagrams.

Strabismus—Strabismus can begin at birth, as the child matures or even in adulthood. Second only to refractive error, strabismus is the most common eye abnormality in infants and children. It is present in about 4 percent of the population.

While it is common for a newborn baby’s eyes to wander, within a few weeks of birth, as the baby learns to move the eyes together, the “wandering” should completely disappear. Strabismus threatens visual function and cannot be outgrown. However, when detected early, strabismus often can be corrected.

The most common form of strabismus is esotropia. With esotropia, the eye or eyes turns inward or “cross.” It is most often found in children who are hyperopic. A less common form of strabismus is exotropia. The opposite of esotropia, the exotrope’s eye (or eyes) turns outward and is most often associated with myopia

Accommodative Esotropia—Accommodative esotropia usually occurs in highly hyperopic children between ages two and four years of age. When the child with accommodative esotropia is tired, ill or plays with an object in near-point range, the eye turns in.

Prior to age three years, practitioners most often treat accommodative esotropia, by “overplussing” the child. Overplussing is the use of additional plus power added to a single-vision lens. After age three or when the additional plus power is problematic, multifocals are used to treat accommodative esotropia.

Amblyopia—Often referred to as “lazy eye, amblyopia is a condition of reduced sight, usually in one eye, resulting from poor visual stimulation during the first few years of life. It affects 2 to 4 percent of the population. Amblyopia is responsible for loss of vision in more children than any other form of ocular disease.

MOST COMMON CONDITIONS ENCOUNTERED, BY AGE
	Hyperopia	Myopia	Astigmatism	Accommodative Esotropia	Strabismus	Amblyopia
Preemies		X	X
Infants	X		X
Toddlers to age 3	X		X	X	X	X
3-6 years	X		X	X	X	X
Over 7 years		X	X	X

Without proper stimulation, the visual pathways of the brain develop abnormally. Although the eye may be capable of good vision, the brain does not receive clear images. In strabismic amblyopia, the brain, to avoid double vision, suppresses visual images from one eye. In anisometropic amblyopia, images from one eye are optically blurred, usually from astigmatism or hyperopia. Less frequently, amblyopia is the result of a defect within the eye, such as cataract.

Amblyopia often has no outward symptoms. If treatment is delayed, normal depth perception has no opportunity to develop. Left untreated, amblyopia will lead to permanent vision loss.

Treatment for amblyopia depends on the child’s age, severity of the vision loss and the prescribing doctor’s preference. Treatment options include, vision therapy, total or partial occlusion therapy, prescription eyeglasses or any combination.

Common types of occlusion therapy include the use of eye-patches or optical blurring. Optical blurring can include the use of pharmacological agents (eye drops) or visual degradation using either power to blur the image or foils placed over the lens.

OTHER CONDITIONS

Cataracts—In the United States, approximately 400 to 500 infants are born with congenital cataracts each year. Another 400 to 500 cases develop around the first year of life (Moore, “Eyecare for Infants,” p. 120). Although occurring less frequently than other conditions, congenital cataracts are the leading cause of vision impairment in young children. Children with bilateral congenital cataracts should be operated on as soon after detection as the infant is stable, preferably within the first week of life. Following surgery, immediate visual rehabilitation is essential.

Retinopathy of Prematurity—Retinopathy of Prematurity or ROP is a retinal vascular disease that affects premature and low birth weight infants. The lower the birth weight the greater the risk of developing ROP. Supplemental oxygenation and the lighting in neonatal units have also been linked to the development of ROP. In addition to retinal manifestations, children tend to have amblyopia, strabismus, cataracts, glaucoma, nystagmus and corneal problems.

Nystagmus—Nystagmus is an involuntary, jittery movement of the eyes, which is usually exaggerated by looking in a particular direction. Nystagmus usually develops in infants between six weeks and three months of age. It can occur alone or be associated with other conditions

THE PRESCRIPTION

While the prescription presented may not provide a definitive diagnosis, it may offer valuable clues. We can assume that a +2.00 diopter lens prescribed for a two-year-old child is NOT simply to treat hyperopia. Because it is normal for a child of this age to be hyperopic and the Rx is modest in power, the dispenser immediately suspects the most likely condition, strabismus.

This assumption is far more valuable than immediately apparent. First, it conveys a familiarity with pediatric conditions and promotes confidence in the optician. Secondly, it opens dialog with the parents.

THE PARENTS

When filling an Rx for an in-house doctor, the optician may know why glasses are being prescribed. But, for dispenser’s filling an outside doctor’s Rx, the parents are vital to understanding how the eyewear is to be worn and why it is being prescribed.

Parents usually know the diagnosis, even if they do not understand what it means or the importance of proper management of the condition. They know if occlusion therapy has been prescribed and, if so, the number of hours the eye is to be occluded. Parents know the history of the child’s visual development and the degree of cooperation expected from the child.

The parents may be emotional and confused, but they hold the keys to accurate prescription analysis. It is the parents who will fill-in the missing pieces—pieces essential to the visual welfare of the child.

PUTTING IT ALL TOGETHER

General Assumptions

• Plus or minus power for a toddler is probably prescribed to treat strabismus—esotropia if a plus power and exotropia if a minus power.
• An Rx written for a child aged 10 or over is usually prescribed because of a refractive error, which wearing glasses will not “cure.”
• Plus power, bifocal prescriptions probably indicate accommodative esotropia.
• Modest powers for younger children probably are prescribed to prevent amblyopia.
• Left untreated, strabismus could lead to amblyopia.
• If amblyopia is not treated prior to visual maturity, the child may suffer permanent vision loss not correctable by surgery, spectacles or contact lenses.

USING WHAT WE’VE LEARNED

Parents enter the dispensary with a nine-month-old male infant. They present an Rx of +4.00, O.U., written by a pediatric ophthalmologist six weeks prior. The father says they “only want to look around” and do not need assistance. Let’s look at what may actually be going on.

Based on the date the Rx was written, the parents may be having a difficult time. They may be delaying treatment because they lack confidence in the doctor, because they have received differing opinions, fear social acceptance or because they do not understand the importance of early treatment.

When questioned, the parents say that their older child’s eyes wandered when she was an infant and now she is fine. Their nine-month-old’s eye only turns when he is tired or doesn’t feel well. The parents hope he will outgrow the “crossing” just as their older child did. This presents the pediatric optician with a unique opportunity. This baby’s visual outcome may rest on the next few minutes. If the optician does not engage the parents now, more will be lost than a sale.

We know that:

1. It is normal for a child to be farsighted.
2. While it is normal for an infant’s eyes to wander, it is NOT normal for a nine-month-old baby.
3. Strabismus is the most likely diagnosis.
4. Left untreated, this child may develop amblyopia. It can be assumed this is not currently the diagnosis; based on the O.U. Rx. Asking the parents if the doctor also prescribed “patching” or another form of occlusion therapy can confirm this.

The parents need to know:

1. Different doctors may prescribe slightly different prescriptions. The difference in +4.00 and +4.50 Rx is not as important as getting the child in glasses as soon as possible.
2. A young child wearing glasses is socially acceptable and generally brings only positive comments from others.
3. The Rx is not extreme for this aged child.
4. The risks of NOT treating the child promptly.

LET’S TRY ANOTHER ONE

A five-year-old girl and her mother enter the office, presenting an Rx of +2.00 -0.50 X180, with a 3.00 add, O.U. The doctor has specified polycarbonate, Flattop 28 lenses set to bisect the pupil. The child’s current glasses, prescribed six months prior are single vision, +4.00 +0.50 X180 O.U.

The mother is quite reluctant to put bifocals on her daughter. She is concerned the bifocal set so high will not be safe. (Grandma had trouble adjusting to multifocals, which Mom remembers far too well.) The child’s mother is also worried about the power changing so soon. The child complains she cannot see well out of the glasses so Mom is considering removing the glasses and seeking a second opinion.

We know that:

1. The most likely diagnosis is accommodative esotropia. This is suggested by the “over-plussing” of the original Rx and the subsequent bifocal prescription.
2. Because the accommodative ability of young children is so acute, they usually adapt very easily to the high-segment placement recommended for children less than 10 years of age. The visual system of a young child functions very differently than that of a presbyopic adult.
3. If the child is NOT treated and the eye continues to turn at near point, she may suffer vision loss.

The mother needs to know:

1. This is a standard, customary treatment option.
2. Since the single-vision Rx was problematic, the doctor now is prescribing a multifocal. The multifocal will allow the child to see well at distance, but prevent the eye from turning at near point.
3. The change in treatment plan does not mean the child’s condition is deteriorating or that her eyes changed. It only indicates a need for another treatment option.
4. The child needs to remain in the glasses, even if a second option is desired.

FINAL THOUGHTS

A parent places flotation devices on a toddler playing in a pool. The child is not allowed to enter the pool without them. Yet, the same parent returns to the doctor or dispensary complaining the child refuses to wear the glasses. Why was the parent successful with the “floaties” but not with the glasses?

The parents understand the floaties are essential to the child’s well being. Therefore, they take on sufficient importance to make compliance mandatory. A knowledgeable and caring optician will help the parents understand eyeglasses also are vital to the child’s well being.

Next: If you enjoyed playing detective, you can further draw on the principles of Pediatric Prescription Analysis while learning new dispensing techniques in the follow-up course, Kid’s Kases—Practical Solutions. This advanced course will appear in a later edition of 20/20 magazine and will be available online at www.2020mag.com. Watch for it later in 2008.