Revisiting Piggyback Lens Fitting for Flat
PATRICK J. CAROLINE, FAAO, & MARK P. ANDRé, FAAO
1a. DH's pre-fitting corneal topography OS.
Figure 1b. Topography over +6.00D
1Day Acuvue OS.
We rarely revisit one of our past Case Reports
topics, but when something continues to work so well it definitely deserves a second
look. In the April 2005 column "Fitting Piggyback Lenses on Excessively
Flat Corneas," we described the case of a patient who underwent bilateral radial keratotomies 12 years previously. Post operatively, his left eye experienced significant
corneal flattening with an apical radius of 36.00D and a refraction of OS +4.25
–0.50 x100, 20/25. We successfully altered the profile of the flat cornea
by fitting a +6.00D Night & Day lens (CIBA Vision) and then we piggybacked
a standard GP lens on top.
A Similar Case
More recently, patient DH, a 44-year-old police officer, presented
with an almost identical history. DH underwent RK 15 years ago and experienced radical
flattening to the left eye only. Cor-neal topography revealed simulated Ks OS of
37.62 @ 167/38.50 @ 077 with a paracentral radius of 34.25D. The manifest refraction
was OD +0.75 sphere 20/20 and OS +5.25 –0.25 x175 20/25.
to the surgically induced anisometropia, we fit DH's left eye with a wide range
of soft and GP lens designs and materials. Unfortunately, he was unable to achieve
adequate vision with the soft lenses or adequate comfort with the GPs. We decided
that DH might benefit from a piggyback system.
2a. A spherical GP lens design on DH's left eye.
Figure 2b shows the final piggyback lens combination.
Figure 1a shows DH's pre-fitting corneal topography OS with a
paracentral radius of 34.25D (9.85mm). Figure 1b shows the corneal topography over
a +6.00D 1Day Acuvue soft lens (Vistakon) with a paracentral radius of 41.00D
(8.25mm). Figure 2a shows a spherical GP lens design on DH's left eye with a base
curve radius of 43.00D (7.85mm), with a large, fixed central bubble. Figure 2b demonstrates
the 43.00D (7.85mm) GP lens on top of the +6.00D 1Day Acuvue.
Today, DH's VA with the lenses is stable at 20/20 and he now enjoys
all day lens comfort.
These two cases demonstrate how you can use plus powered soft
lenses (one a Night & Day and the other a 1Day Acuvue) to steepen anterior
corneal topography in individuals who exhibit radical corneal flattening post RK.
Patrick Caroline is an associate
professor of optometry at Pacific University and is an assistant professor of ophthalmology
at the Oregon Health Sciences University. He is also a consultant to Paragon Vision
Sciences and SynergEyes, Inc. Mark André is an associate professor of optometry
at Pacific University. He is also a consultant for Alcon Labs, CooperVision and
Contact Lens Spectrum, Issue: October 2006