Article Date: 10/1/2006

contact lens case reports
Revisiting Piggyback Lens Fitting for Flat Corneas


Figure 1a. DH's pre-fitting corneal topography OS.

Figure 1b. Topography over +6.00D 1•Day 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.

Due 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.

Déjà Vu

Figure 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 1•Day 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 1•Day 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 1•Day 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 SynergEyes, Inc.

Contact Lens Spectrum, Issue: October 2006