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FITTING CONTACT LENSES FOR PEDIATRIC APHAKIA
CAITLIN J. MORRISON, OD, & DAVID P. LIBASSI, OD
Managing a child with contact lenses can be a daunting task. However, knowing what types of lenses are available to troubleshoot can turn an anxiety-inducing encounter into a simple one.
Pediatric aphakia typically occurs when a child is either born with a cataract or later develops one within the first five years of life. Congenital cataracts are surgically extracted, ideally within the first weeks of life, leaving the child without a natural lens. Until a child’s eye finishes developing, an intraocular lens implant should not be the first option. Instead, a highly breathable contact lens should be the go-to solution. Here are some tips from the SUNY College of Optometry to help you get started.
Initial Fitting Process
In the initial fitting process, begin with a silicone elastomer contact lens for pediatric aphakia. Silicone elastomer lenses are the only pediatric aphakic lenses cleared for continuous wear, which is a significant advantage when fitting a 1-month-old infant. They are easy to fit, and there is less of a chance that a child will lose a silicone elastomer lens as opposed to a GP lens, according to a study by Russell et al (2012).
To start, use a child’s age to select the initial lens with a high plus prescription, steep base curve, and small diameter. Perform retinoscopy through the diagnostic lens to determine the appropriate lens correction. A clear path for the retinal reflex should be observed. If a red reflex is difficult to observe, referral back to the pediatric ophthalmologist is appropriate to determine the health of the post-surgical retina. However, it may help to select a starting power from the averages in Table 1 (Sclafani, 2002).
|0 to 12 months||+29D to +32D|
|12 to 24 months||+20D to +26D|
|> 2 years||+12D to +20D|
A child’s age dictates where the child will hold his or her visual stimuli. A child’s final contact lens prescription should be over-corrected by +2.50D to +3.00D to compensate for the absence of accommodative abilities.
The diagnostic lens base curve may also be chosen based on a child’s age. Determine the appropriate base curve-to-cornea relationship with the use of fluorescein dye. The corneal shape of an infant or small child will initially be steep and will become flatter with time (Table 2) (Friling et al, 2004). As a pediatric aphake matures, flattening of the lens base curve will be necessary to maintain an appropriate fit.
|Pre-term infants||53.13D (6.35mm)|
|Full-term infants||47.50D (7.11mm)|
|Children 2 to 4 years||43.69D (7.73mm)|
Other Contact Lens Options
Are the parameters of silicone elastomer lenses not meeting a patient’s needs? Try fitting with a custom soft or GP contact lens. Both of these lens types are available in a wide range of high plus power, astigmatic correction, base curve, and lens diameter choices. Unfortunately, a major disadvantage of these lenses is their lack of extended or continuous wear approval.
Due to the nature of soft lens materials, we are unable to use fluorescein dye to determine the base curve-to-cornea fitting relationship. Consequently, a hand-held slit lamp or a 20D lens with trans-illuminator lighting are required to assess fitting characteristics.
With GP contact lenses, one major advantage is their ability to mask corneal astigmatism, especially if a toric soft lens had difficulty maintaining stability on a child’s eye.
When fitting a GP lens, first select a diagnostic lens with a high plus power (+10.00D to +20.00D) and small diameter (8.5mm to 9.0mm). Due to the significant contact lens mass of a high-plus correction and the small contact lens diameter needed to align patients’ small corneal diameter, it is imperative to begin the fitting process with appropriate pediatric diagnostic parameters.
Lens Handling and Wear
Once you have determined the appropriate contact lens prescription and fit, we recommend carefully training the parents on lens application and removal. One method to ensure that the parents develop excellent lens handling skills is to require lens removal each night and application the following morning.
Once parents are confident in their newfound skills, extending lens wear hours may be considered. Depending on the modality, the lenses approved for overnight wear can be removed every third night.
Schedule weekly follow-up visits with the patients and their parents to determine the suitable lens power and fit and to reinforce the parents’ degree of success with lens application, removal, and disinfection.
One study found that no matter the birth weight of the infant, the radius of corneal curvature reached normal childhood range at around 12 weeks after birth. The corneal curvature progressed to reach adult levels at around 3 years of age (Friling et al, 2004).
This study provides clinical evidence about how rapidly the fit of the lens, as well as the prescription, may change from birth to 3 years. Because of this, it is optimum to see children back every three months after the initial fitting process to check the parameters and condition of the current lens. CLS
To obtain references for this article, please visit www.clspectrum.com/references and click on document #252.
Dr. Morrison currently practices at New York Eye and Ear Infirmary in New York City. She has received travel expenses, stipend or reimbursement from CooperVision and Valley Contax.
Dr. Libassi is an assistant clinical professor at SUNY Optometry and has been the supervisor for the Cornea and Contact Lens Residency program since 1992. From 1995 to 2005, Dr. Libassi served as the SUNY Principle Investigator for the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study.