Article Date: 5/1/2005

contact lens case reports
Fitting Corneal Reshaping Contact Lenses Post-LASIK
BY PATRICK J. CAROLINE, FAAO, & MARK P. ANDRÉ, FAAO

Figure 1. "Mini island" post LASIK.

Figure 2. CRT lens OD. Note the change in corneal topography pre-fitting vs. post fitting.

Figure 3. CRT lens OS. Again, note the flattening of the post-fitting central corneal topography.

While LASIK outcomes continue to improve, cumulative complications in the procedure can take place secondary to pre-surgical calculations, surgical technique and postoperative wound healing, all of which are difficult to predict or control. When we add late-onset refractive change (increased myopia) to the list, it becomes clear that a number of post-LASIK patients may experience suboptimal vision following the procedure (Figure 1).

Post-LASIK Residual Myopia

A case in point is patient TW, who underwent uncomplicated LASIK surgery in 2002 for correction of 4.00D of myopia. Her post-surgical refractive error stabilized at OD ­0.75D and OS ­1.50D. She presented interested in undergoing overnight corneal reshaping to correct her residual refractive error.

We informed TW as to the off-label nature of the procedure.

We began by referencing TW's pre-surgical refractive and keratometric data, which were: OD ­4.25 ­0.50 x 180, Ks 45.75 @ 180/46.50 @ 090, OS ­4.00 ­0.50 x 180, Ks 45.50 @ 180/45.75 @ 90. We entered these data into the Paragon CRT Slide Rule and calculated diagnostic lenses as if TW had never undergone LASIK. The suggested diagnostic lenses were OD 8.3 .575 ­34, OS 8.3 .550 ­34; however, we've learned that in fitting CRT lenses post LASIK, it's necessary to steepen the landing zone angle by two degrees.

We placed onto TW's eyes diagnostic lenses with the steeper peripheral angles, followed by fluorescein pattern evaluation, looking for centration and 4mm to 5mm of central treatment zone. We dispensed TW the following CRT lenses: OD 8.3 .550 ­36, OS 8.3 .550 ­37 and instructed her to wear them overnight.

CRT Success

One week after overnight lens wear, the apical radius of TW's right cornea had flattened 0.62D (Figure 2) and the left apical radius had flattened 1.63D (Figure 3). She enjoys stable 20/15 vision OU throughout the day and wears her CRT lenses only every other night.

Patrick Caroline is an associate professor of optometry at Pacific University and is an assistant professor of ophthalmology at the Oregon Health Sciences University. 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.

 

 


Contact Lens Spectrum, Issue: May 2005