title: Rigid gas-permeable contact lens fitting in LASIK patients for the correction of multifocal corneas.
abstract: BACKGROUND
  Laser in situ keratomileusis (LASIK) has recently become the most commonly performed refractive surgery procedure. Results are promising in correcting low to moderate myopia. Most complications occur during the surgeon's learning curve. One of the complications is a decentration of the ablated 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 efficacy of rigid gas-permeable contact lens designs and fitting techniques used in eight eyes with multifocal LASIK ablations to correct haloes and impaired 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 corneal topographic map, 0.2 mm outside the ablated refractive area, for selection of the back optic zone radius of the RGP contact lenses. Procedures for lens fitting are described. Visual acuity (high-contrast logarithm of the minimum angle of resolution, LogMAR) 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 spectacle-corrected visual acuity was +0.3 LogMAR (SD 0.19; in Snellen equivalent, 20/40) and improved significantly with the contact lenses to +0.08 LogMAR (SD 0.11; in Snellen equivalent, 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 combination with selection of the back optic zone radius 0.2 mm peripheral of the refractive ablation zone, facilitate contact lens fitting to restore best-corrected visual acuity in LASIK patients with multifocal corneas.
authors.affiliation: Academic Hospital Maastricht, Department of Ophthalmology, The Netherlands. fred.eggink@hotmail.com
authors.forename: F A
authors.initials: FA
authors.lastname: Eggink
authors.forename: W H
authors.initials: WH
authors.lastname: Beekhuis
authors.forename: R M
authors.initials: RM
authors.lastname: Nuijts
mesh_terms: D000328:Adult; D003261:Contact Lenses; D003316:Corneal Diseases / Q000175:diagnosis / Q000209:etiology / Q000628:therapy*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D017755:Prosthesis Fitting; D014786:Vision Disorders / Q000175:diagnosis / Q000209:etiology / Q000628:therapy*; D014792:Visual Acuity