contact lens case reports
An Option for Post-LASIK Cases
BY PATRICK J. CAROLINE, FAAO, & MARK P. ANDRÉ, FAAO
One of the more frequent long-term complications to modern LASIK surgery is uncorrected refractive error, most commonly as residual myopia. This can be effectively corrected through surgical enhancement procedures, contact lenses, or spectacles. However, in our hands the list of correction options would be incomplete if we didn't mention overnight corneal reshaping (orthokeratology).
While some patients elect to undergo an enhancement, in some cases additional surgery may be contraindicated because of corneal thickness, residual dry eyes, or financial limitations. For some patients the only remaining correction options are either glasses or contact lenses, the two modalities they had hoped to eliminate through refractive surgery. Clinical experience has taught us that when presented with the various options, some patients feel that overnight corneal reshaping fits best into their current lifestyle.
Post-LASIK Myopia Progression
Our patient is a 32-year-old male who underwent LASIK surgery at age 26 for correction of −6.50D of myopia. He enjoyed 20/20 uncorrected visual acuity for approximately four years, then began to experience a slow but steady decline in uncorrected visual acuity in both eyes, a decline he attributed to beginning law school at age 29.
Today, his residual refractive error is OD −1.50D sphere 20/20 and OS −2.00D sphere 20/20. We obtained his original pre-operative keratometric and refractive data, with K readings of OD 42.75/43.25 and OS 43.00/43.50 with a manifest refraction of −6.50D sphere OD and OS.
In fitting post-LASIK patients for overnight corneal reshaping, we design the initial lenses based on patients' pre-operative Ks and prescription and fit them as if they never had refractive surgery. In this situation, the Paragon CRT (Paragon Vision Sciences) calculator suggested diagnostic lenses of OD 9.5 0.550 −33 and OS 9.4 0.550 −33. We ordered these lenses and evaluated their lens-to-cornea fitting relationship with fluorescein. The desired fluorescein pattern should look identical to that seen in normal, unoperated eyes, with centration and a 4mm to 5mm treatment (applanation) zone (Figure 1).
Figure 1. Fluorescein pattern of the CRT lenses dispensed to the patient.
We ultimately dispensed the following CRT lenses: OD 9.5 0.525 −32 and OS 9.4 0.525 −32 for overnight wear. Within five days the patient was elated with his 20/20 uncorrected visual acuity, which was stable throughout his waking hours (Figures 2 and 3). While CRT post-LASIK remains an off-label use, it might be a modality to consider for certain selected patients. CLS
Figure 2. Corneal topography of the patient's post-LASIK right eye pre- and post-CRT, note the flattening of the post-fitting axial map and the corneal profile (below the map) along the flat corneal meridian.
Figure 3. Corneal topography of the patient's post-LASIK left eye pre- and post-CRT.
Patrick Caroline is an associate professor of optometry at Pacific University. He is also a consultant to Paragon Vision Sciences. Mark André is an associate professor of optometry at Pacific University. He is also a consultant for CooperVision.