title: Improved technique of circular keratotomy for the correction of corneal astigmatism.
abstract: BACKGROUND
  Based on Gauss' law governing the comparison of hyperbaric pressure in the eye and atmospheric pressure, the authors present a procedure to correct astigmatism. The present paper describes an improvement of a technique for circular keratotomy that was published previously.
  
  
  METHODS
  We present data on a consecutive series of 32 eyes with a mean corneal astigmatism of 4.66 diopters (D) (range -2.25 to -6.00 D) with a variety of clinical diagnoses. The astigmatic cornea was trephined with a diameter of 7 mm and a depth of 300 microns. After deepening of the trephination with a diamond knife to 550 microns over the steeper semimeridians, the intraocular pressure created a rounding of the cornea. The amount of astigmatic correction and extent of deepening were controlled intraoperatively with a keratoscope. No sutures were placed.
  
  
  RESULTS
  In 32 consecutive eyes, corrections were between 50 and 90% of the initial cylindrical values after 1 week to 1 month. In 29 eyes (91%), the results obtained remained stable during a 1-year follow-up; in two eyes (6%), the 1-month results worsened by more than 1.00 D and in one eye (3%), results improved by more than 1.00 D. There were no complications during or after surgery. Wound gaping resulting in epithelial plugs did not occur. No patient lost one or more lines of spectacle-corrected visual acuity, but 13 eyes (40%) gained one or more lines.
  
  
  CONCLUSIONS
  The technique of correcting corneal astigmatism by trephining to a depth of 300 microns, with deepening of the wound to 550 microns along the steep meridian and using no sutures can correct up to 10.00 D of astigmatism with reasonable stability.
authors.affiliation: Martin-Luther-Hospital, Bochum, Germany.
authors.forename: J H
authors.initials: JH
authors.lastname: Krumeich
authors.forename: A
authors.initials: A
authors.lastname: Knülle
authors.forename: J
authors.initials: J
authors.lastname: Daniel
mesh_terms: D001251:Astigmatism / Q000601:surgery*; D003315:Cornea / Q000473:pathology / Q000601:surgery*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007646:Keratotomy, Radial / Q000295:instrumentation / Q000379:methods*; D011446:Prospective Studies; D016896:Treatment Outcome; D014792:Visual Acuity