The contact lens aspect of optometric practice is always an exciting and challenging component of our profession. Working with infants and toddlers brings this excitement and challenge to a new level and often results in our most rewarding patient experiences.
Although most of the standard skills of contact lens practice apply, often the optometrist must fit and evaluate the patient with just a penlight and a retinoscope. The good news however is that by managing just a few of these cases, you can quickly acquire the skills of caring for this population. The key element of success is educating and counseling the parents and caregivers.
Why Fit Toddlers?
There are several reasons to fit contact lenses on infants and toddlers. Key among them is the prevention of amblyopia. The most common cause of this problem is some type of anisometropia.1 When there is a significant difference in refractive error at a young age, the brain learns to use only the eye with the best focus.
After a relatively short time, the brain will shut down the pathway of vision for the fellow eye and will never develop a neurological center for detailed vision for that eye. This is followed by the absence of any binocular vision centers in the brain.
Leading the way in causes for this refractive error difference is a monocular cataract. Cataract surgery can lead to monocular aphakia.2 Today, we remove cataracts as soon as the lens opacity begins to affect vision performance or development. When present at birth, its ideal to remove them in the first week of life. An infant eye is too small for an adult refractive power, so implants should generally be avoided until the teen years. A typical aphakic refractive error for contact lenses in an infant is +32.00, a six-year-old is +23.00 and an adult is +13.00. Contact lenses are the treatment of choice for pediatric aphakia.2
The second most common reason for vision correction is accommodative esotropia, often accompanied by high hyperopia.1 In addition to the heavy weight of lenses for higher power correction, the image distortion and magnification inherent in these lenses make spectacle correction less than satisfactory for children. Children often look over the glasses to avoid the image problem. The full amount of plus power can be prescribed easily with contact lens correction. In some cases, you can also correct a significant amount of the latent hyperopia. The contact lens management of this problem can often completely resolve the esotropia.
Another medical indication for fitting children with contacts is high refractive error. The spectacle correction of myopia, hyperopia or astigmatism of greater than 5.00D results in a change in image size that will adversely affect visual development in children under five years of age.1 Thick glasses also weigh heavy on a young face and can cause permanent disfigurement of the bridge of the nose and in some cases affect the angle of the ears.
Also, corneal distortion at any age leads to a degraded image and loss of visual acuity. Keratoconus leads the way as the most common reason for this problem in adults, but for children the most common reason is trauma, including birth trauma.3 As in adults, the first line of management for this problem is rigid contact lenses. For young children, uncorrected corneal distortion will lead to amblyopia.
Less common but equally important medical reasons for fitting kids with contacts are light control for anirida or ocular albinism. Custom soft contact lenses can be darkly tinted and made with an opaque iris ring.
Contact lenses can also help a child overcome the social problems that can accompany thick glasses. Children who have to wear glasses from a young age can develop the feeling that they are defective and this can lead to the handicap stigma. Glasses on a child can also lead to low self-esteem. Contact lenses, when fit prior to school, can minimize or eliminate these social problems.
Recipe for Success
Fitting contacts on infants and small children is not as difficult as you might imagine. It requires some self-confidence and a few clinical pearls as noted below.
On initial exam, a comprehensive history from the parents or care-givers is critical. Involve the family from the start so that they can provide the necessary support. For medical problems such as aphakia or other conditions where amblyopia is a concern, consider an aggressive extended wear lens to minimize disruption of the visual input to the brain.
Aphakia is the most common reason for vision correction in an infant.
Your examination of the cornea and anterior segment is best preformed at the slit lamp. For infants and very small children, this is sometimes impossible and a good penlight exam with the magnification of a head-borne loupe magnifier is acceptable. You can judge the corneal integrity by the clarity of the iris and overall corneal reflex. The conjunctiva should be white and have a healthy light reflex. Use a Burton lamp to check for fluorescein or rose bengal staining.
Whenever possible, use the retinoscope with cycloplegia to determine refraction. Be sure to compensate for vertex distance, as these lenses are often of significant power. In aphakia for example, a calculated prescription of +24.00 at the spectacle plane would translate to a contact lens power of +29.00. Also, you must factor in the working distance for these patients. A baby does not watch TV or drive a car. Most of the visual development of a baby occurs at one to three feet. Focus babies and small children with +1.00 to +3.00D over the distance prescription. You can move the focus out to the distance once the child starts school.
Trial and Error
Trial lenses are a must for fitting this patient population. Until you can feasibly obtain keratometry readings, rely on the trial fitting to establish the relative corneal curvature. Some basic observations can also be helpful. Microphthalmic eyes and highly myopic eyes are most likely to have a steep cornea. While megalocornea, high hyperopia or a large eye tend to have a flat cornea. For most cases however, these clues are not available so youll need a basic starting point:
RGPs. For rigid gas permeable fitting, a good initial trial lens has a diameter of 9.5 and a base curve of 7.50. This should allow you to evaluate fluorescein patterns with a Burton lamp.
An alignment to slightly steep pattern is the most desirable fit. Cycloplegic retinoscopy over the lens can help determine the power.
When ordering the custom lens, use a high Dk material and make the peripheral curves tighter than you normally would for a typical fit. Fit the lens with an overall tight philosophy. Lens ejection or displacement is a major issue with this population and just counseling against eye rubbing is ineffective.
Soft Lenses. For soft lens fitting, you will often need a custom, daily wear lens. A diameter of 12.5 and a base curve of 7.7 is your best starting point. Some manufacturers have custom fitting sets available with color-coded base curves. These lenses all have the same diameter and power. All lenses of the set are dumped into a Petri dish. This system allows for a quick assessment of the 7.7, 7.9 and 8.1 base curve on the eye. A penlight evaluation works well after a short, five minute adjustment period. A central bubble indicates a tight fit. A generous but stable movement is ideal due to the low water content of these lenses.
Overnight orthokeratology is an option for patients with myopia and astigmatism. Topography before and after shows the change in central base curve.
Cataracts are a common problem for infants, especially in premature children. Aphakia is often a complication of the surgical management of cataracts and is the most common reason for vision correction in an infant. Fit these patients in the office setting at the end of the first postoperative week. You should be able to fit the lens at this point because the surgical wound is normally healed enough and the risk of infection is minimal. Have the parent or guardian hold the child while you examine with a penlight.
The Silsoft lens from Bausch & Lomb is a good lens choice for these cases, use a base curve of 7.5, a diameter of 11.3, and a power of +32.00. To insert the lens, grasp it between the thumb and first finger and apply a gentle pressure to create a taco shape. Using the other hand, elevate the infants lid slightly, creating a space between the lid and the globe. Then, flipping the taco upside down, slip the lens in under the upper lid into the space.
You can remove the lens using two common techniques. The first is the standard soft lens removal procedure. Gently pinch the lens between the thumb and first finger. The Silsoft lens has a fairly rigid profile and fits with a high surface tension. Therefore, the optometrist and care-giver must have very clean, dry, and oil-free fingertips to remove this lens easily.
The second method is to approach the child from the side and use the index finger of each hand on the upper and lower lid respectively. Expose the cornea and lens and massage toward the cornea until the lens ejects. Instruct the parents or caregivers on these techniques during the fitting process to minimize manipulation of the eye. In the monocular aphakic child, patching is also a critical element of care. Depending on the age and clinical circumstances, patching ranges from full time to part time and should be coupled with vision stimulation techniques, such as television programs, video games or other lines of vision therapy.
Custom fitting sets that are available with color-coded base curves allow quick assesment of each lens on the eye.
This program also allows you to see the child more often and maintain control of solutions, wearing schedule, lens hygiene, proper lens fit, and optimal lens power. Annual contact lens programs, in general maximize clinical success.
A new option for managing children with contact lenses is the Paragon CRT program. Paragon received FDA approval for their Cornea Refractive Therapy program without age limits. This program uses a reverse geometry lens design in a very high Dk material to reshape the cornea during overnight wear. Approved for myopia of up 6.00D and astigmatism up to 1.75D, this program is ideal for children. The younger cornea responds faster to the treatment than adults and the total reversibility of this program makes it a safe alternative to traditional contact lens fitting.5
Fitting contact lenses for infants, toddlers, children, and young adults is an exciting, challenging, and highly rewarding aspect of optometry. Hospital-based optometry challenges the profession with many new clinical situations, which have led to creative new applications of contact lens treatment. The overwhelming success of the aggressive contact lens management of amblyopia and other serious ocular medical problems has paved the way for a more aggressive approach to everyday refractive problems of children. The thoughts and tips in this article should help every optometrist take a fresh look at this issue.
Dr. Edmonds is co-director of the Contact Lens and Low Vision Service at Wills Eye Hospital in Philadelphia. He also owns Edmonds & Associates group practice and is president of the Edmonds Group, a health-care consulting firm specializing in managed eye care.
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3. London, R., Cole, R.G., Rosenthal, B.P. Problems in Optometry. Vol. 4, Number 1. Philadelphia: J. B. Lippincott Company, 1992: 13-19.
4. Kogan, B. A., Walline, J. J., Rah M. J. Two studies examine overnight orthokeratology in adults, children. Primary Care Opt News 2002:12/1.
5. Edmonds, S.A. Contact Lens Management of Aphakic Children. Contact Lens Forum 1990; 15:#8, 15-18.
6. Catania, L. J., Edmonds, S. A., Shovlin, J. P. The Contact Lens in Therapy 1984. vol. 3, number 2; Anterior Segment at Risk: 35-83.