title: Intrastromal correction of presbyopia using a femtosecond laser system.
abstract: OBJECTIVE
  To introduce a new, minimally invasive intrastromal correction for presbyopia (INTRACOR procedure) using the TECHNOLAS femtosecond laser system (Technolas Perfect Vision GmbH).
  
  
  METHODS
  The INTRACOR procedure was performed in 83 eyes of 45 patients aged 44 to 67 years. Follow-up was 6 to 12 months. Data recorded included age; pre- and postoperative refraction; uncorrected distance (UDVA), intermediate, and near visual acuity (UNVA); corrected distance visual acuity (CDVA); distance corrected near visual acuity; corneal hysteresis (CH), corneal resistance factor (CRF), and asphericity; pachymetry; endothelial cell density; contrast sensitivity; and ocular aberrations.
  
  
  RESULTS
  At 6 months postoperatively, all 83 (100%) eyes had improved UNVA, with minimal or no change in UDVA. Twenty-two eyes were available at 12 months; UNVA improved to J1 in these eyes with continued improvement in mean UDVA. At last follow-up, a mild myopic shift in refraction was noted with only 3 (3.6%) eyes showing a 2- or 3-line decrease of UDVA, and 74 (89.2%) eyes achieved both J2 and 20/25 or better. Mean CDVA and distance corrected near visual acuity continued to improve with time. Two (2.4%) eyes lost 2 lines of CDVA at 6 months, but this did not occur in the 22 eyes seen at 1 year. Overall stability was noted in CH, CRF, pachymetry, endothelial cell density, and contrast sensitivity. Primary spherical aberrations shifted toward negative values and secondary spherical aberration shifted toward positive values. No corneal structural complications were observed.
  
  
  CONCLUSIONS
  The INTRACOR intrastromal procedure using the TECHNOLAS femtosecond laser is a promising procedure for presbyopia correction. It preserves the corneal epithelium and anterior stromal fibers.
authors.affiliation: Centro Oftalmológico Colombiano, Bogotá, Colombia. luisantonio.ruiz@gmail.com
authors.forename: Luis Antonio
authors.initials: LA
authors.lastname: Ruiz
authors.forename: Liliana Marcela
authors.initials: LM
authors.lastname: Cepeda
authors.forename: Vanessa Carolina
authors.initials: VC
authors.lastname: Fuentes
mesh_terms: D000328:Adult; D000368:Aged; D015350:Contrast Sensitivity / Q000502:physiology; D003319:Corneal Stroma / Q000601:surgery*; D005500:Follow-Up Studies; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D053844:Lasers, Solid-State / Q000627:therapeutic use*; D008875:Middle Aged; D011305:Presbyopia / Q000601:surgery*; D012029:Refraction, Ocular / Q000502:physiology; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology