title: [Changes in high order aberrations of anterior and posterior surfaces of cornea before and after phacoemulsification].
abstract: OBJECTIVE
  To study the effects of phacoemulsification surgery on the optical high order aberrations (HOA) of the cornea measured with Pentacam.
  
  
  METHODS
  It was a prospective case series study. HOAs of the anterior and posterior surface of cornea were measured before and after phacoemulsification surgery on 51 eyes of 45 patients. Monofocal foldable IOLs were implanted after phacoemulsification through a clear-cornea, 3.2 mm incision without suture. Patients were observed 1 day before surgery, and at 7 days, 1 month and 3 months after surgery. HOAs included the total high order aberration (tHOA), spherical aberration (SA), coma, trefoil, 3rd, 4th, 5th, 6th order aberrations. Root-mean-square (RMS) values of HOAs were obtained with 3 mm and 6 mm aperture using corneal topography of Pentacam pre- and postoperatively, and were divided into 3 mm and 6 mm aperture groups. Aberrations were compared in each eye using repeated measures and the optical changes induced by surgery were investigated.
  
  
  RESULTS
  The total HOA of the anterior surface increased slightly from a mean of (0.289 +/- 0.171) microm preoperatively to (0.312 +/- 0.158) microm postoperatively with 3 mm aperture; and (0.980 +/- 0.215) microm preoperatively to (1.054 +/- 0.308) microm postoperatively with 6 mm aperture, respectively. The increase was not statistically significant (F = 1.55, P = 0.22), and the changing trend of the total HOA was similar between the two groups of 3 mm and 6 mm aperture (F = 0.95, P = 0.42). The changes of other HOAs were similar to the total HOA pre- and postoperative. The total HOA of the posterior surface increased significantly from (0.548 +/- 0.220) microm preoperatively to (0.661 +/- 0.275) microm postoperatively with 3 mm aperture, and (1.780 +/- 0.453) microm preoperatively to (1.945 +/- 0.532) microm postoperatively with 6 mm aperture. The increase was statistically significant (F = 15.83, P = 0.00). The changing trend of the total HOA showed statistically difference between these two groups (F = 12.46, P = 0.00). The changes of other HOAs were similar to the total HOA pre- and postoperatively.
  
  
  CONCLUSIONS
  Phacoemulsification cataract surgery does not systematically degrade the optical quality of the anterior corneal surface. However, it introduces significant changes in most HOAs of the posterior surface of cornea, so the surgery may degrade the optical quality of the posterior corneal surface.
authors.affiliation: Clinical College of Ophthalmology, Tianjin Medical University, Tianjin Eye Hospital, Tianjin 300020, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Wang
authors.forename: Xin
authors.initials: X
authors.lastname: Tang
authors.forename: Shuai
authors.initials: S
authors.lastname: Zhang
authors.forename: Li-hua
authors.initials: LH
authors.lastname: Li
mesh_terms: D000368:Aged; D003315:Cornea / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018918:Phacoemulsification; D011184:Postoperative Period; D011446:Prospective Studies; D012029:Refraction, Ocular; D012030:Refractive Errors; D014792:Visual Acuity