Fitting After Refractive Surgery: Is There Hope?
contact lens case reports
Fitting After Refractive Surgery: Is There Hope?
BY PATRICK J. CAROLINE, FAAO, & MARK P. ANDR, FCLSA
June 1999
Today's most common visual problems following refractive corneal surgery are related to
under and overcorrections, which frequently result in anisometropia and a loss of
binocular function. ss
Standard daily disposable or frequent replacement soft contact lenses often provide the
necessary convenience and optical correction for many patients. However, more complex
contact lens designs may be necessary for individuals with post-surgical irregular
astigmatism, significant central corneal flattening or decentered ablations.
The Patient and The MacroLens
A 32-year-old male underwent bilateral PRK surgery in 1997 (OS in January and OD in
March). His preoperative refractive error was OD -6.75 -0.75 x 180, OS -7.00 -0.75 x 175
with visual acuities of 20/20 OU. One year postoperatively, uncorrected visual acuities
were 20/100 OD , 20/25 OS, and his residual refractive error was OD +4.00 -0.25 x 40 and
OS -0.50 -0.50 x 165 (Fig. 1). Due to the patient's overcorrection OD and symptomatic
anisometropia, we suggested contact lens wear. Numerous RGP and soft lens designs were
tried and failed but were solved with the MacroLens (C&H Contact Lenses).
FIG. 1: Map of patient's OD post-PRK.
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The MacroLens is a large diameter, semi-scleral RGP lens, available in diameters from
13.9mm to 15.0mm. Its advantages over traditional RGP designs include centration with
stable optics over the pupil, total masking of all corneal cylinders and greater comfort
due to scleral support. It has a large limbal fenestration vent to facilitate tear flow
beneath the lens and to prevent lens adhesion. A diagnostic set of 12 lenses is available
with base curves from 46.00D to 40.50D, and diameters from 13.9mm to 15.0mm.
Fitting Recommendations
Measure the visible horizontal iris diameter and identify the flat K reading. The
optimum lens fit should exhibit relative alignment across the central and midperipheral
cornea. A band of tear film pooling should be present at the peripheral cornea adjacent to
the limbus (Fig. 2). This patient's post-surgical topography showed a slight pooling in
the central cornea with excellent midperipheral lens alignment (Fig. 3).
FIG. 2: Optimum fluorescein pattern of the MacroLens on a normal,
unoperated eye.
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FIG. 3: The MacroLens on patient's right eye, post-PRK.
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The MacroLens has been comfortable and versatile for many of our patients. Its ability
to center on irregular and asymmetric corneas has made it an extremely important addition
to our fitting armamentarium for the abnormal cornea.
Patrick Caroline is an associate professor of optometry at Pacific University and
an assistant professor of ophthalmology at the Oregon Health Sciences University. Mark
Andr is director of contact lens services at the Oregon Health Sciences University.