title: Correction of pre-existing astigmatism during cataract surgery: comparison between the effects of opposite clear corneal incisions and a single clear corneal incision.
abstract: BACKGROUND
  Opposite clear corneal incisions (OCCIs) have been reported to reduce pre-existing astigmatism (PEA) during cataract surgery. Our goal was to evaluate the effect of OCCIs on correcting PEA in cataract surgery.
  
  
  METHODS
  Non-randomized prospective study. Thirty-four patients with PEA of greater than 1.5 diopters (D) underwent clear cornea phacoemulsification cataract extraction with 3.2-mm OCCIs (OCCI group). The control group consisted of 23 successive patients with PEA <1.5 D who underwent cataract extraction without OCCI. Best-corrected visual acuity, keratometry and refraction were recorded for all patients pre-operatively and post-operatively.
  
  
  RESULTS
  Using keratometric findings, mean astigmatism correction was 1.3 D (+/-0.9 SD; decreased from 2.6 D pre-operatively to 1.4 D post-operatively) in the OCCI group but only 0.4 D in the control group (P<0.005), 8 months post-operatively. Vector analysis of astigmatism correction showed greater change for OCCI patients (1.8 D vs 1.0 D, P=0.002). Using the Holladay method for calculating surgically induced refractive change (SIRC), the OCCI group showed a higher value of SIRC (-1.6 D vs -0.97 D), but this was not statistically significant. The OCCI patients showed a greater and significant change in refraction spherical equivalent than the controls. No complications related to OCCI or cataract surgery occurred during the follow-up period.
  
  
  CONCLUSIONS
  Opposite clear cornea incision seems to be a simple, predictable, safe and effective procedure in reducing pre-existing corneal astigmatism in cataract surgery. It has an enhanced effect in correcting astigmatism compared to a single clear cornea incision when using keratometric findings value but not when using refractive data. Future studies are needed to document the long-term effect of OCCI and to evaluate the correlation between incisions of different size and astigmatism correction.
authors.affiliation: Goldschleger Eye Institute and Department of Ophthalmology, Sheba Medical Center, Tel Aviv University, Tel Hashomer, Israel. simon@jsei.ucla.edu
authors.forename: Guy J
authors.initials: GJ
authors.lastname: Ben Simon
authors.forename: Howard
authors.initials: H
authors.lastname: Desatnik
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001251:Astigmatism / Q000601:surgery*; D003315:Cornea / Q000601:surgery*; D019781:Corneal Topography; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D018918:Phacoemulsification; D011446:Prospective Studies; D012029:Refraction, Ocular; D014792:Visual Acuity