title: Assessment of contrast sensitivity loss after intrastromal femtosecond laser and LASIK procedure.
abstract: OBJECTIVE
  To assess the loss of contrast sensitivity (CS) function for INTRACOR or intrastromal femtosecond laser presbyopia procedure to conventional LASIK procedures.
  
  
  METHODS
  Patients were recruited from a refractive surgery center for either INTRACOR or conventional LASIK. INTRACOR was performed on 8 eyes and LASIK was performed for 40 eyes in an overlapping period. Pre-operative evaluation and post-operative follow up for up to three months was done. Drops of CS in 4 spatial frequency (3 cpd, 6 cpd, 12 cpd and 18 cpd) right before and 3mo after the surgery were compared by Wilcoxon signed ranks test.
  
  
  RESULTS
  For INTRACOR, CS threshold showed significant drop at both glare and non-glare condition, the drop was seen in all 4 spatial frequency. The averaged loss over the 4 spatial frequencies 3mo after surgery was 1.18 for non-glare and 0.71 for glare. For LASIK the CS threshold drop was most significant in 12 cpd for glare.
  
  
  CONCLUSIONS
  INTRACOR procedure produces a gain of near vision for presbyopia patients but also introduces a high lost of contrast sensitivity plus worsen of vision quality. Pre-surgical patient selection and advise should be given with specific regards to night driving and glare conditions.
authors.affiliation: Far Eastern Memorial Hospital, Taipei 100, Taiwan, China.
authors.forename: Elsa L C
authors.initials: EL
authors.lastname: Mai
authors.affiliation: National Changhua University of Education, Changhua 500, Taiwan, China.
authors.forename: Ie-Bin
authors.initials: IB
authors.lastname: Lian
authors.affiliation: Taiwan Nobel Eye Institute, Taipei 100, Taiwan, China.
authors.forename: David C K
authors.initials: DC
authors.lastname: Chang
keywords: INTRACOR; Intrastromal femtosecond laser; LASIK; contrast sensitivity