title: [Comparative study of multifocal LASIK for the correction of pre-presbyopic myopia].
abstract: OBJECTIVE
  To evaluate the feasibility of multifocal LASIK for the correction of pre-presbyopic myopia
  
  
  METHODS
  In this prospective,comparative case series, thirty-two patients were recruited into the study,mean age was (38.5 +/- 2.7) years, standard LASIK using Planoscan was performed on the patient's dominant eye, while multifocal LASIK was performed on the nondominant eye. Routine examinations included distance and near vision, refraction, corneal topography, intraocular pressure, ultrasonic corneal pachymetry, contrast sensitivity function, amplitude of accommodation ,depth of defocus, wavefront aberration.
  
  
  RESULTS
  The mean follow-up duration was 6.67 +/- 2.75 (range, 6 to 11 months). In the nondominant eyes,the near visual acuity was statistically significant difference, better in the postoperative visual acuity, however, there was no statistically significant difference between preoperation and postoperation in dominant eyes. The Q value of 6 mm diameter in the nondominant eyes was 0.081 +/- 0.274 (range, -0.53 to +0.53) and 0.464 +/- 0.266 (range, - 0.02 to +0.99) in the dominant eyes, significant difference were noted between two groups. Topography revealed high degree refractive power zone of (5.64 +/- 3.05) mm2 at central cornea in nondominant eyes. The wavefront analysis showed that after the multifocal procedure, a positive spherical aberration was induced ,which is opposite to that normally seen following a standard LASIK treatment for myopia. At 6 months, the nondominant eyes attained pseudoaccommodation of (0.84 +/- 0.61) diopters (range, 0 to 2.25 D), the amplitude of pseudoaccommodation are related to corneal multifocal index, spherical aberration. However, amplitude of accommodation was decreased (0. 10 +/- 0.67) diopters in dominant eyes at 6 months visit.
  
  
  CONCLUSIONS
  The results of this study show that multifocal LASIK is safe and effective in preserving near vision for pre-presbyopic myopia patients . Multifocal LASIK are reasonably to induce pseudoaccommodation by decreasing negative spheric aberration.
authors.affiliation: State Key Laboratory of Ophthalmology & Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China.
authors.forename: Guo-Fu
authors.initials: GF
authors.lastname: Huang
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang
authors.forename: Bin
authors.initials: B
authors.lastname: Yang
authors.forename: Xiao-Xiao
authors.initials: XX
authors.lastname: Zhang
authors.forename: Ping
authors.initials: P
authors.lastname: Qiu
authors.forename: Sheng
authors.initials: S
authors.lastname: Zhou
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery*; D011184:Postoperative Period; D011305:Presbyopia; D011446:Prospective Studies; D016896:Treatment Outcome; D014792:Visual Acuity