title: [Comparative study of the tilt, decentration and higher-order aberrations (HOA) of single-piece and 3-piece tecnis aspheric intraocular lenses].
abstract: OBJECTIVE
  To compare the tilt and decentration between a single-piece and a 3-piece aspheric intraocular lens (IOL), and the impact of these factors on the HOAs after phacoemulsification and IOL implanted in capsular bag.
  
  
  METHODS
  It is a prospective randomized clinical trial. According to the table of random number, 72 eyes of 49 patients were divided into 2 groups. One group received a 1-piece aspheric IOL (Tecnis ZCB00, AMO) and a 3-piece aspheric IOL (Tecnis ZA9003, AMO) in the other group. The tilt at 45°, 90°, 135° and180° and decentration of the IOL were obtained using Scheimphlug system (Pentacam,Oculus) and image-analysis 3 months after the surgery. The internal ocular HOA of the IOL were evaluated with iTrace examination. The tilt and decentration of the IOL and the variables of the internal ocular HOAs were compared by independent-samples t test. The effect of tilt and decentration on the HOAs was assessed by Pearson correlation analysis.
  
  
  RESULTS
  Patients age ranged from 50 to 80 years. The best corrected visual acuity (BCVA) of both group were all not less than 0.5. In 3-piece IOLs group, there was a significant positive correlation between the BCVA and the astigmatism (Z3) (r=0.504, P=0.003; r=0.637, P=0.000) and a significant negative correlation between the BCVA and the fourth-order astigmatism (Z13) of the 3-piece aspheric IOL group [(0.90±0.78)° and (0.98±0.73)°, respectively] were higher than those in 1-piece aspheric IOL group [(0.50±0.33)° and (0.69±0.41)°, respectively], the differences were statistically significant (t=2.899, P=0.005; t=2.120, P=0.038). At 5.0 mm pupil, the defocus (Z4), astigmatism (Z5), third-order coma (Z8), fourth-order astigmatism (Z11) and fourth-order spherical (Z12) in 3-piece aspheric IOLs group were higher than those in 1-piece aspheric IOL group, the difference were statistically significant (t=2.372, P=0.021; t=2.801, P=0.007; t=3.269, P=0.002; t=3.230, P=0.002; t=3.468, P=0.001). In 3-piece IOL group, a significant positive correlation was found between the mean tilt and the fourth-order astigmatism (Z13) at 3.0 mm and 5.0 mm pupil (r=0.396, P=0.023; r=0.378, P=0.030), and a significant negative correlation was also found between the decentration and the fourth-order astigmatism (Z13) with at 3.0 mm pupil (r=-0.441, P=0.010).
  
  
  CONCLUSIONS
  Both 1-piece and 3-piece IOL designs showed well stability in capsular bag, the former was slightly more stable with better visual quality. There was no significant correlation between the internal ocular HOA and the degrees of IOL tilt and decentration in the 1-piece aspheric IOL group. At different pupil diameters, a significant correlation was found between the decentration and tilt of IOL and fourth-order astigmatism Z (13) in the 3-piece IOL group.
authors.affiliation: The Eye Hospital of Wenzhou Medical University, Wenzhou 325027, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Yu
authors.affiliation: The Eye Hospital of Wenzhou Medical University, Wenzhou 325027, China.
authors.forename: Pingjun
authors.initials: P
authors.lastname: Chang
authors.affiliation: The Eye Hospital of Wenzhou Medical University, Wenzhou 325027, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Li
authors.affiliation: The Eye Hospital of Wenzhou Medical University, Wenzhou 325027, China.
authors.forename: Yongmou
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: The Eye Hospital of Wenzhou Medical University, Wenzhou 325027, China; Email: 13819707056@qq.com.
authors.forename: Yun'e
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D006801:Humans; D019654:Lens Implantation, Intraocular; D007908:Lens, Crystalline; D007910:Lenses, Intraocular; D018918:Phacoemulsification; D011446:Prospective Studies; D011680:Pupil; D014792:Visual Acuity