title: Rainbow glare as an optical side effect of IntraLASIK.
abstract: OBJECTIVE
  To report a new optical side effect associated with the IntraLASIK procedure.
  
  
  METHODS
  Retrospective chart review and questionnaire of all patients treated with IntraLASIK from June 2004 to August 2005.
  
  
  METHODS
  A cohort of 585 eyes (312 patients) was divided sequentially into those treated with the older-model IntraLase laser (group 1: 399 eyes of 215 patients) and those treated with the newer model (group 2: 186 eyes of 97 patients).
  
  
  METHODS
  Preoperative and postoperative refraction, visual acuity, pupillometry, pachymetry, intraocular pressure, mean topographic power and cylinder, wavefront aberrations, and answers to a questionnaire of symptoms were recorded. The precise spatial extent of the rainbow spectrum was drawn by select patients for calculation of the diffractive grating size responsible for the light scatter. A glass slide was also irradiated and photographed using the older model to simulate the rainbow spectrum.
  
  
  METHODS
  The symptom of rainbow glare was correlated with preoperative and postoperative factors and time between the most recent service call and surgery.
  
  
  RESULTS
  In group 1, 90.2% of patients were successfully contacted, and 37 (69 eyes) reported symptoms of rainbow glare around lights, for an incidence of 19.07%. In group 2, 88.6% of patients were contacted, and 2 (4 eyes) reported similar symptoms, for an incidence of 2.32%. The odds ratio (OR) between the 2 groups is 9.4 (P<0.001). For every 10-mum increase in ablation depth, the OR is 1.2 (P = 0.038), and for every 30 days from the last service call, it is 1.5 (P = 0.007). The spatial extent of the color pattern was used to calculate the spacing array at approximately 9 mum, corresponding to the laser spot and line separation.
  
  
  CONCLUSIONS
  Light scattering from the back surface of the IntraLASIK flap creates a spectral pattern whose visual impact is clinically inconsequential in the majority of patients. The spectral pattern and visual angle correspond to a grating size that matches the raster spot separation of IntraLase pulsing. Eyes treated with newer focusing optics of higher numerical aperture reduced the rainbow symptom. Variance in optical quality and numerical aperture can impact the spot size and uniformity of IntraLase flap creation.
authors.affiliation: Department of Refractive Surgery, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA. krueger@ccf.org
authors.forename: Ronald R
authors.initials: RR
authors.lastname: Krueger
authors.forename: Ivey L
authors.initials: IL
authors.lastname: Thornton
authors.forename: Meng
authors.initials: M
authors.lastname: Xu
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Bor
authors.forename: Thomas J T P
authors.initials: TJ
authors.lastname: van den Berg
mesh_terms: D019466:Glare; D006801:Humans; D006956:Hyperopia / Q000601:surgery; D015994:Incidence; D007429:Intraocular Pressure / Q000502:physiology; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects*; D054018:Lasers, Excimer / Q000009:adverse effects*; D008027:Light; D009216:Myopia / Q000601:surgery; D016017:Odds Ratio; D012029:Refraction, Ocular / Q000502:physiology; D012189:Retrospective Studies; D012542:Scattering, Radiation; D013524:Surgical Flaps / Q000473:pathology*; D011795:Surveys and Questionnaires; D014786:Vision Disorders / Q000209:etiology*; D014792:Visual Acuity / Q000502:physiology