Finding the Cause
of Soft Toric Lens Intolerance
PATRICK J. CAROLINE, FAAO, & MARK P. ANDRé,
Figure 1. Right eye inferior microcystic
Figure 2. Left eye inferior microcystic
The patient is a 47-year-old female with a 15-year
history of wearing soft lenses. We first evaluated her 12 months ago when her chief
complaint was a growing intolerance to her 38 percent water
polymacon, prism ballasted toric soft lenses that she replaced yearly. She used
a multipurpose solution nightly for cleaning and disinfection.
At the initial visit her visual acuities with contact lenses were
OD 20/50, OS 20/30. A sphero-cylinder over-refraction revealed a minimal improvement
in visual acuity. Manifest refraction OD was –3.75 –3.25 x 015, 20/40,
OS –3.25 –5.50 x 175, 20/30. Keratometric readings were OD 44.00 @ 008/48.37
@ 098, OS 43.87 @ 170/50.37 @ 080.
Slit lamp examination showed bilateral micropannus, superficial
punctate keratitis and inferior epithelial microcystic edema consistent with a localized
corneal hypoxia (Figures 1 and 2). We performed photokeratoscopy and videokeratography.
Both eyes showed significant inferior corneal distortion (Figure 3). We diagnosed
her with possible hypoxia-induced corneal distortion and advised her to discontinue
lens wear for four weeks.
she returned one month later, manifest refraction was OD –3.00 –2.75
x 010, 20/20, OS –3.25 –3.00 x 170, 20/20 and keratometric readings
were OD 43.50 @ 012/46.87 @ 102 and OS 44.00 @165/47.50 @ 075. Slit lamp examination
showed no distortion by either photokeratoscopy or videokeratoscopy.
Figure 3. Inferior corneal distortion by photokeratoscopy.
We refit her with Frequency 55 Toric XR lenses (CooperVision)
manufactured in 55 percent water methafilcon A material, OD 8.4 –3.25 –2.25
x 010 14.4mm, OS 8.4 –3.25 –2.25 x 170 14.4mm. She's worn them for 10
months with no recurrence of corneal edema. Her visual acuities are 20/20 OU with
no spectacle blur when alternating from lenses to glasses.
A Thinner Profile
This case demonstrates the long-term effects of wearing thick,
low-Dk, prism ballasted soft lenses. While this type of edema response is rare,
it illustrates that corneal hypoxia can occur in patients wearing traditional toric
soft lenses. These patients may benefit from lenses that incorporate a thinner overall
design profile and/or higher Dk materials.
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 director of contact lens services
at the Oregon Health Sciences University and serves as an assistant professor of
optometry at Pacific University. He is also a consultant for Alcon Labs, CooperVision
and SynergEyes, Inc.
Contact Lens Spectrum, Issue: September 2005