Contact Lens Materials for Babies
LORETTA B. SZCZOTKA-FLYNN, OD, MS, FAAO
As I write this column, I'm awaiting my second
child. While in the hospital, I know I'll do the same thing with my second
child as I did with my first: Grab the ophthalmoscope and make sure that my baby doesn't have a cataract.
For those unfortunate few babies who do have a cataract, contact
lenses fortunately are available to help them visually rehabilitate once they
undergo cataract surgery in the first few weeks of life. Here, I reflect on some
characteristics of babies that make them so special and how knowing those characteristics
will help you fit them with contact lenses.
Babies are Resilient
Babies don't stay mad at us when we let them cry themselves to
sleep, and they forget about mommy and daddy leaving them with a babysitter. Medically,
they heal well and they heal quickly. In fact, you can fit contact lenses within
a week of an infant's cataract surgery.
If our first lens doesn't work, we can try another. Multiple lens
material options are available for babies. The Silsoft lens (Bausch & Lomb)
is a pure silicone elastomer lens. It features a range of powers, three base curves
and two diameters, although powers between +20.00D and +32.00D come in 3.00D steps.
GP materials are also an option, and they offer unlimited parameters.
It takes skill to fit babies with GP lenses, and often I accompany the surgeon
to the operating room and fit the lens prior to cataract removal, then I order the
lens power empirically.
Lastly are low-Dk hydrogels. These lenses offer a decent selection
of curvatures, powers and diameters, but they suffer in extremely low oxygen transmissibility
in high plus powers.
Babies Sleep a Lot
Because babies' eyes are closed for about two-thirds of the day
(if you're lucky!), you should use materials approved for extended wear. In fact,
I typically recommend a three- to four-day extended wear schedule. This is
one reason why I never fit low-Dk hydrogels on babies; corneal swell-ing will undoubtedly
occur over time. The Silsoft lens has a Dk of 340, which makes it a tremendous material
for overnight use.
GP lenses can also provide enough oxygen transmission for safe
extended wear. My favorite materials are Menicon Z (Menicon Co., Ltd.), Fluoroperm
151 and HDS 100 (Paragon Vision Sciences) and Boston XO (B&L).
Babies Frequently Cry
Crying is a baby's way of telling us something is wrong, but babies
quickly turn happy once we attend to their needs. Contact lens fitting for babies
also has its ups and downs. Although the Silsoft lens has phenomenal material properties
for oxygen transmission, comfort and stability on an infant's eye, lipid deposits
can limit the life of the lens to only a few months. The hydrophobic material repels
water and creates a non-wettable surface.
Silicone hydrogel lens manufacturers have tried to remedy this
situation by combining hydrogel and silicone properties, often with a surface treatment
to make the surface wettable. I look forward to the day when manufacturers allow
custom orders in silicone hydrogel disposable materials for these tiny patients.
Dr. Szczotka-Flynn is an
associate professor at Case Western Reserve University Dept. of Ophthalmology and
is director of the Contact Lens
Service at University Hospitals of Cleveland.
Contact Lens Spectrum, Issue: February 2006