CARING FOR THE EYECARE NEEDS of pediatric patients presents interesting challenges and opportunities to improve lifelong vision and quality of life. Infants and young children have very plastic visual systems that are in the process of development, which makes providing the best possible vision critical.
Medically necessary contact lenses can help these young patients develop a functional visual system that can create vision in an eye that would otherwise be unable to see. Contact lenses can also make an impact on children who have normally developed vision who are myopic, as contact lenses can be fit to create peripheral hyperopic defocus to slow the progression of myopia in children.
Contact lenses have also been shown to make an impact on hand-eye coordination and self-image,1,2 making contact lens wear a compelling option in children who wear spectacles. This article will present different applications for fitting pediatric contact lenses and some tips for success.
MEDICALLY NECESSARY LENSES IN INFANTS AND CHILDREN
Aphakia It has been found that the overall prevalence of childhood cataract and congenital cataract was in the range from 0.32 to 22.9/10,000 children and 0.63 to 9.74/10,000, respectively.3 Infants born with cataracts have the best visual outcome when the lens is surgically removed within the first months of life.4,5 Bilateral infantile cataracts are typically genetic and the resulting bilateral aphakia after surgery can be corrected by either spectacle or contact lens correction.
Cases of unilateral cataracts have been reported to be close to half of the total cases of infantile cataracts.3,6 Unilateral infantile cataracts are generally considered to be idiopathic, although one recent study found numerous cases that were associated with persistent fetal vasculature.7 This association is most obvious clinically when persistent hyperplastic primary vitreous (PHPV) is present. Both an infantile cataract and PHPV require surgery to remove the elements blocking the visual system, and early removal also results in the best visual outcome.8
While surgical removal of cataracts has become the standard of care, the reconstruction of the optical system in these infants has been greatly debated in recent history. In the mid-2000s, the Infant Aphakia Treatment Study (IATS) was initiated to compare visual acuity and adverse events in contact lens wear compared to intraocular lens (IOL) implantation in infants after monocular cataract removal.9 In this 12 multisite study, 114 infants between 28 and 210 days of age, who were diagnosed with unilateral cataracts, underwent surgery and were randomized to either IOL placement or correction with a contact lens. Infants who have an IOL were under-corrected by 6-8D based on age and prescribed glasses to over-correct the patient by 2D .
Infants randomized to treatment with contact lenses were fit with either a silicone elastomer lens or a corneal rigid GP contact lens with a 2D overcorrection. The overcorrection was used to move the point of focus in infants in both groups to a near point. All infants wore a patch over the non-operated eye for one hour per day per each month of age until 8 months of age, and then for half of the infant’s waking hours after 8 months of age.10 At 1 year of age, the visual acuity was assessed by Teller acuity grating.10
The mean visual acuity of the two groups was not statistically different. However, a high number of adverse events and additional surgeries were required for infants in the IOL group. As a result of this study, surgeons are told to take caution when considering implanting an IOL following cataract surgery on infants under 7 months of age, and to utilize contact lenses for optical correction.11,12
Correction of aphakia with contact lenses includes several options.13 A silicone elastomer contact lens provides high oxygen permeability that allows for extended wear of these lenses in infants.14,15 Silicone elastomer contact lenses are available in 3D steps and three different base curves. Other lenses can be custom made in order to correct for the highly hyperopic powers resulting from aphakia.
Custom soft lenses can be made in this prescription range, but handling is difficult due to the low modulus of these materials, particularly if an infant is uncooperative. In addition, the oxygen permeability is poor, particularly in the high-plus powers in which a thick lens is required. Corneal rigid GP contact lenses are quite successful with these patients.16,17 Lens materials are available with high oxygen permeability and handling is easy to teach to parents and children as they grow older. The ability to customize the prescription and refine the fit of corneal GP lenses makes them a straightforward choice for infants and their parents.
Fitting an infant with lenses works best if the infant is seated either on the lap of the parent (Figure 1) or comfortably in a car seat or stroller (Figure 2). If application of lenses can be accomplished quickly without a need to restrain the baby, future daily application and removal of lenses will not become a fearful event. Giving the infant fingers to grab or something to hold onto can keep their hands away from their face as the lenses are “touched” onto the cornea while their eyes are open.
Keeping the lens application quick and “silly” (I like to use a “boop” sound effect when I put them on the eye) makes it a fun “game”—and often the baby looks back in surprise when they can see their surroundings. As the parents should remove lenses before bedtime each day, making lens application and removal fun will make adding this new task to their lives as simple as possible.
Similarly, removal of lenses can be accomplished by first placing the index fingers on the upper and lower lid margins and pulling the lids apart just enough to see both the top and bottom of the contact lens, and then moving the lid margins toward each other with just enough inward motion to “scoop” one or both of the lid margins under the lens edge. Older toddlers who are being fit after they become strong and opinionated may require some restraint, and lenses can be gently slid under the upper eyelid without hurting the cornea. However, trying to make lens application and removal as positive as possible should always be the goal.
Evaluation of the lenses while on the eye can be accomplished by touching a fluorescein strip wet with saline on the front surface of the lens. As a lens material with a UV filter is needed in these children who do not have their own natural lens to filter UV light from reaching the retina, the fluorescein pattern can be dim. However, the pattern is certainly viewable with a cobalt filter on a direct ophthalmoscope or a handheld slit lamp.
Lenses fit best when the lens edge is under the upper lid. Larger diameters keep the lenses in the eyes and prevent an infant from easily rubbing a lens out of the eye. Consider fitting lenses with an overall diameter of 10mm or slightly larger, although care must be taken to make sure that “chubby cheeks” can’t force lenses out with a giant smile and a forceful blink.
Retinoscopy over the lens allows the practitioner to determine whether a power change is needed. Children under the age of two should be over-corrected so that near vision is put into focus. Consider giving an extra +3.00D of power in order to create clear vision at the close working distance of an infant.
After a toddler reaches two years of age, their world shifts from near to distance, and contact lenses should be fit to correct distance vision, with a pair of spectacles worn over the lenses with a flat-top segment bifocal and a high add power (generally +3.00D in toddlers). Using polycarbonate lenses in spectacles gives additional UV protection and impact resistance.
Of course, much work occurs after the lenses are fit, particularly if amblyopia is present. Discussions with parents about the importance of patching is critical at every visit. A stable contact lens fit is generally followed every six months at this age, and amblyopia is typically monitored every two or three months, so the infant’s eyes and lenses are viewed several times in one year.
Irregular Corneas Unfortunately, an irregular cornea can occur in children, resulting from trauma at birth, an accident, or an infection that created a corneal scar.18-20 A rigid corneal GP lens is best for this scenario, as they can best correct irregular astigmatism. GPs can be fit similarly to the method
described above for aphakia. Depending on the age of the child and the cause of the irregular astigmatism, some older children may be fearful of the lens being applied. Extra time may be needed to help make the experience positive. Quick hands when applying lenses are a must!
Keratoconus is another cause of irregular corneas in children. Prompt consultation with an ophthalmologist for consideration of corneal cross-linking is important. Early keratoconus can be fit with rigid corneal lenses easily, and children generally can apply and remove these lenses on their own whether at home or at school. As a result of the extra supplies and effort needed for scleral lens care, rigid corneal lenses may be a better choice for most children.
Anisometropia Hyperopic anisometropia can cause amblyopia in children. A retrospective study of anisometropic amblyopes found that best-corrected vision with contact lenses was improved over spectacle wear, even after children had been “maximally treated” with a spectacle and patching regimen.21 Often, these children can be fit with soft contact lenses, depending on the prescription. Careful attention to vertexing the prescription and fully correcting any astigmatism, if present, is important. Vision with contact lenses should be at least equal to that of vision with spectacle correction upon fitting the lenses, as the purpose of fitting these lenses is to improve vision.
Myopia Slowing the progression of myopia in children is of great interest, as worldwide rates of myopia are increasing globally. Five billion people are expected to have myopia and 1 billion people are expected to have high myopia (–5.00D or more) by 2050.22 These predictions indicate that half of the world’s population will have myopia, and 10% of the population will have high myopia.22
People with myopia have higher axial length (longer eyes), which is stretched and often thinned by continued growth.23As a result, eyes with myopia, and especially high myopia, are associated with a number of ocular health complications later in life, which can lead to vision impairment. These include myopic macular degeneration, retinal detachments, cataracts, and glaucoma.22,23 Two types of contact lens designs—soft distance-centered multifocal lenses and orthokeratology lenses—are reported to create peripheral myopic defocus, which is a mechanism by which myopia progression can be slowed in children.24
SOFT MULTIFOCAL CONTACT LENSES FOR SLOWING MYOPIA PROGRESSION IN CHILDREN
Soft, distance-center multifocal lenses have been studied in the Bifocal Lenses in Nearsighted Kids (BLINK) study. Study participants who wore distance-center multifocal contact lenses with +2.50D addition power resulted in an average slowing of the progression of myopia by 0.46D compared to single-vision contact lenses over three years.25Those wearing a +1.50D add did not have a significant difference in myopia progression compared to the single-vision lens wearers, and it is proposed that the higher add power creates a greater amount of peripheral defocus than the lower add powers.
While distance-center soft multifocals have been used off-label for myopia control for several years, one soft multifocal was approved by the U.S. Food and Drug Administration (FDA) for the purpose of slowing the progression of myopia in children aged 8 to 12 years with –0.75D to –4.00D of myopia and 0.75D or less of astigmatism. A three-year study of these single-use lenses showed that they resulted in significantly less increase in spherical equivalent myopia and axial length elongation when compared to single vision contact lenses.26
ORTHOKERATOLOGY LENSES FOR SLOWING MYOPIA PROGRESSION IN CHILDREN
Orthokeratology lenses use a reverse geometry lens design to reshape the cornea and flatten the central area, known as the treatment zone.27 When wearing the lenses, the corneal epithelial cells shift toward the area with greater clearance created by the return zone, resulting in a flatter central cornea.28
By flattening the central cornea with the base curve by an amount corresponding to the amount of the patient’s myopia, a patient can see during the day without glasses or contact lenses. The process is temporary, and lenses generally need to be worn each night in order to see clearly the following day. Control of the return zone and the angle of the landing zone can change the treatment effect, centration, and fit of the lenses.
Much like the central distance correction with surrounding add power in a soft multifocal lens used for myopia control, creating a central treatment zone to correct for distance vision surrounded by an uncorrected portion within the visual axis creates myopic defocus on the peripheral retina.
Studies have shown that significantly less axial length growth occurs in children using orthokeratology lenses compared to spectacles and soft single-vision contact lenses.29,30 As these lenses require overnight wear and, therefore, have higher risk associated with use, they are considered to be Class 3 devices.31 Although reverse geometry lenses were approved by the FDA for orthokeratology in 2002, they were not approved for the purpose of myopia management until 2021.32
By making a treatment zone smaller than the size of the pupil, the surrounding zone creates myopic defocus on the peripheral retina.33 The Retardation of Myopia in Orthokertology (ROMIO) study, a two-year study comparing axial length in children wearing orthokeratology lenses overnight compared to spectacle lenses, found less axial length growth in those using orthokeratology lenses.29 Similarly, the Corneal Reshaping and Yearly Observation of Nearsightedness (CRAYON) study compared orthokeratology to single-vision soft contact lenses and also found significantly less axial elongation with orthokeratology.30 Numerous studies have followed, with attention to axial length to assess myopic progression.
Patients using orthokeratology should ideally have no refractive error that requires correction during the day, thereby making cycloplegic refraction an invalid parameter to measure progression. Assessing changes in axial length makes sense for all myopia control methods, as the health complications resulting from highly elongated eyes are one of the primary reasons that myopia progression is a concern. Axial length can be measured with ultrasound biometry, which requires contact with the ocular surface, or optical biometry, which is noncontact.34 A 0.1mm increase in axial length is approximately equal to a 0.25D increase in refractive error.
Parents should be made aware that fitting orthokeratology lenses requires multiple follow-up visits beyond the first fitting visit, including one visit the morning after the lenses were worn overnight for the first time, and follow-up visits at one week and one month, at a minimum. Some children need additional visits to master application and removal. Children should be taught to apply and remove the lenses themselves and should be supervised by parents. It is best not to have parents apply and remove contact lenses unless the lenses are medically necessary.
CONTACT LENSES FOR REFRACTIVE ERROR
As children are active in sports, dance, and a variety of activities that benefit from contact lens wear, soft lenses are a great choice for children with most types of refractive error. Fitting high hyperopes with contact lenses helps increase their visual field by eliminating the magnification that high-plus-power lenses create.
Hand-eye coordination has been shown to be improved with contact lens wear in adults when compared to spectacle wear, so it is likely that contact lenses could also be beneficial for children involved in sports that utilize these skills.35 The Contact Lenses in Pediatrics (CLIP) study found that teaching lens application and removal may take about 15 minutes longer for children aged 8 to 12 years compare to children aged 13 to 17 years old.36 Explaining the need for extra time and patience by family members when scheduling appointments can help to create realistic expectations and a pleasant experience for both kids and parents.
CONCLUSION
Fitting children with contact lenses can make a positive impact on the vision and lives of children. Playing a part in the visual development of children who have a medical need for contact lenses is very gratifying, and it is a privilege to watch their vision improve as they grow. Building relationships with all kids who wear contact lenses is a joy, and practitioners and patients both appreciate the accomplishments that they achieve together on the contact lens fitting journey.
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