title: Time course of induced astigmatism after canaloplasty.
abstract: OBJECTIVE
  To study the changes in astigmatism after canaloplasty and to analyze its correlation with long-term intraocular pressure (IOP) results.
  
  
  METHODS
  Twenty-six eyes of 26 consecutive patients with primary open-angle glaucoma (n=14) and pseudoexfoliative glaucoma (n=12) undergoing canaloplasty were included in this retrospective study. Canaloplasty comprised of 360-degree catheterisation of Schlemm canal by means of a flexible microcatheter with distension of the canal by 2 tensioning 10-0 polypropylene sutures. Primary outcome measures included IOP, glaucoma medication usage, astigmatism, and adverse events at 2, 4, 12, and 24 weeks postoperatively.
  
  
  RESULTS
  The mean preoperative IOP was 21.1±5.8 mm Hg. The mean IOP decreased to 14.25 ±4.3 mm Hg at 6 months. Mean astigmatism preoperatively was 0.77±0.5 D, which increased to 3.3±1.7 D at 2 weeks postoperatively (P≤0.05; Wilcoxon-test). Thereafter, the astigmatism underwent a spontaneous decline, reaching 1.9±0.8 D at 4 weeks and 1.2±0.74 D at 12 weeks postoperatively. Best-corrected visual acuity did not change significantly. Six months after canaloplasty, mean astigmatism reached the preoperative range of 0.86±0.52 D. Astigmatism at 2 weeks correlated significantly and inversely with IOP at 6 months (r=0.59, P=0.005; Spearman).
  
  
  CONCLUSIONS
  The change of astigmatism after canaloplasty follows a clear time course with a maximum at 2 weeks reaching preoperative values at 6 months. The amount of surgically induced astigmatism might be helpful to predict outcome of canaloplasty in terms of IOP reduction.
authors.affiliation: *Department of Ophthalmology, University Hospital Erlangen, Erlangen †Department of Ophthalmology, University of Cologne, Cologne, Germany ‡Department of General Ophthalmology, Medical University of Lublin, Lublin §Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland.
authors.forename: Michaela C
authors.initials: MC
authors.lastname: Moelle
authors.forename: Claus
authors.initials: C
authors.lastname: Cursiefen
authors.forename: Robert
authors.initials: R
authors.lastname: Rejdak
authors.forename: Folkert K
authors.initials: FK
authors.lastname: Horn
authors.forename: Anselm G M
authors.initials: AG
authors.lastname: Jünemann
mesh_terms: D001251:Astigmatism / Q000209:etiology* / Q000503:physiopathology; D002404:Catheterization; D017889:Exfoliation Syndrome / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D018463:Filtering Surgery / Q000379:methods*; D005902:Glaucoma, Open-Angle / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D016850:Limbus Corneae / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D012189:Retrospective Studies; D013524:Surgical Flaps; D013997:Time Factors; D014065:Tonometry, Ocular; D014792:Visual Acuity / Q000502:physiology