title: Corneal shape changes after 2.0-mm or 3.0-mm clear corneal versus scleral tunnel incision cataract surgery.
abstract: OBJECTIVE
  To compare changes in corneal shape and in regular and irregular corneal astigmatism after 3.0- or 2.0-mm clear corneal incision cataract surgery (CICS) with those occurring after 3.0- or 2.0-mm scleral incision cataract surgery (SICS).
  
  
  METHODS
  Randomized, comparative clinical trials.
  
  
  METHODS
  Ninety patients scheduled for bilateral cataract surgery were randomized to 1 of 2 groups: 3.0- or 2.0-mm CICS in the left eye and 3.0- or 2.0-mm SICS in the right eye or CICS in the right eye and SICS in the left eye.
  
  
  METHODS
  All patients underwent CICS and SICS at the 9-o'clock meridian in fellow eyes.
  
  
  METHODS
  Induced corneal astigmatism was determined using vector analysis, and the averaged changes in corneal shape and irregular astigmatism were examined using videokeratography before surgery and at 2 days and 1, 2, 4, and 8 weeks after surgery.
  
  
  RESULTS
  For the 3.0-mm incision, induced astigmatism was significantly greater in the CICS group than in the SICS group (P < or = 0.0329) at 2 weeks and later. The average of difference map on videokeratography in the CICS group showed a marked wound-related flattening and coupled steepening around the flattened area at 2 days after surgery, and these changes persisted for up to 8 weeks: the changes were markedly less in the SICS group. Among the irregular astigmatic components, higher-order irregularity in the CICS group was greater than that in the SICS group (P<0.0001). For the 2.0-mm incision, no significant difference was found between the CICS and SICS groups in induced astigmatism or in irregular astigmatic components. The average of difference map of the CICS group showed a slight wound-related flattening around the incision at 2 days after surgery, but this decreased by 2 weeks; the map of the SICS group showed little change.
  
  
  CONCLUSIONS
  Changes in corneal astigmatism and shape after 2.0-mm CICS are virtually the same as those after 2.0-mm SICS, whereas those occurring after 3.0-mm CICS are significantly greater than those occurring after 3.0-mm SICS, which suggests that CICS is suitable for microincision cataract surgery.
  
  
  BACKGROUND
  The author(s) have no proprietary or commercial interest in any materials discussed in this article.
authors.affiliation: Hayashi Eye Hospital, Fukuoka, Japan. hayashi-ken@hayashi.or.jp
authors.forename: Ken
authors.initials: K
authors.lastname: Hayashi
authors.forename: Motoaki
authors.initials: M
authors.lastname: Yoshida
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Hayashi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001251:Astigmatism / Q000175:diagnosis / Q000209:etiology*; D003315:Cornea / Q000473:pathology* / Q000601:surgery; D019781:Corneal Topography; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular; D008297:Male; D008866:Microsurgery / Q000379:methods*; D008875:Middle Aged; D018918:Phacoemulsification / Q000379:methods*; D011183:Postoperative Complications; D012590:Sclera / Q000601:surgery*; D013524:Surgical Flaps; D014792:Visual Acuity / Q000502:physiology