Rigid gas-permeable contact lens fitting in LASIK patients for the correction of multifocal corneas

Background: Laser in situ keratomileusis (LASIK) has recently become the mo st commonly performed refractive surgery procedure. Results are promising i n correcting low to moderate myopia. Most complications occur during the su rgeon's learning curve. One of the complications is a decentration of the a blated area that causes monocular diplopia and a nocturnal halo phenomenon due to a multifocality of the corneal surface overlying the entrance pupil. The corneal shape is significantly altered after LASIK. We evaluate the ef ficacy of rigid gas-permeable contact lens designs and fitting techniques u sed in eight eyes with multifocal LASIK ablations to correct haloes and imp aired night vision complaints. Methods: We used large-diameter tetra-curved rigid gas-permeable (RGP) contact lenses for visual recovery in eight eyes of seven LASIK patients. We used the power on the transition zone of the c orneal topographic map, 0.2 mm outside the ablated refractive area, for sel ection of the back optic zone radius of the RGP contact lenses. Procedures for lens fitting are described. Visual acuity thigh-contrast logarithm of t he minimum angle of resolution, Log-MAR) was measured before- and 6 months after contact lens fitting. Results: Large-diameter tetra-curve RGP lenses with a mean diameter of 11.85 (SD 0.16) mm were successfully used in LASIK patients with multifocal corneas. Mean best spec tacle-corrected visual acu ity was +0.3 LogMAR (SD 0.19; in Snellen equivalent, 20/40) and improved si gnificantly with the contact lenses to +0.08 LogMAR (SD 0.11; in Snellen eq uivalent, 20/25, P=<0.01). During the follow-up period of 16.7 months, the average daily wearing time of the lenses was 12.5 h. Contact lenses with a standard geometry were not useful due to excessive movement and inadequate centration. Conclusions: Contact lenses with large diameters, in combinatio n with selection of the back optic zone radius 0.2 mm peripheral of the ref ractive ablation zone, facilitate contact lens fitting to restore best-corr ected visual acuity in LASIK patients with multifocal corneas.