title: Surgical control of late postkeratoplasty astigmatism with or without the use of computerized video keratography: a prospective, randomized study.
abstract: OBJECTIVE
  To assess the effectiveness of computerized videokeratography (CVK) in refining the surgical design and in improving predictability of surgical correction of postkeratoplasty astigmatism.
  
  
  METHODS
  A prospective, controlled, randomized, clinical trial.
  
  
  METHODS
  A total of 31 postkeratoplasty eyes, divided into 2 groups (group A, 16 eyes; group B, 15 eyes), with more than 4 diopters (D) of disabling astigmatism were studied.
  
  
  METHODS
  All eyes were treated with a combination of arcuate relaxing incisions and compression sutures. The surgical plan in group A was based on topographic information, whereas in the control group B, the surgical plan was based on information obtained by refraction and keratometry alone.
  
  
  METHODS
  Change in the surgical plan induced by the CVK information, astigmatism, topographic patterns, and factors associated with outcome were measured.
  
  
  RESULTS
  In all 16 cases of group A, the use of CVK changed some aspect of the surgical plan. At 12 months after surgery, both groups showed a significant net reduction (P = 0.001) of baseline astigmatism. However, the reduction (47% and 41 % for groups A and B, respectively) did not differ significantly between the two groups. The topographic astigmatism at 12 months measured 4.24 +/- 0.71 D in group A and 5.60 +/- 0.51 D in group B (P = 0.139). Significant differences between the two groups at 12 months were seen only for keratometric astigmatism (3.60 +/- 0.81 D in group A vs. 5.77 +/- 0.52 D in group B, P = 0.035) and refractive astigmatism (2.34 +/- 0.37 D in group A vs. 4.88 +/- 0.52 D in group B, P = 0.000). The mean vector surgical effect was 91 % for group A and 70% for group B. Regular astigmatism patterns had a greater benefit from surgery than irregular patterns (P = 0.008). Previous refractive surgery was associated with less-favorable outcome (P = 0.045).
  
  
  CONCLUSIONS
  The current study indicates that the use of CVK provides a benefit compared to keratometry and refraction alone in the planning and outcome of surgical treatment for high postgraft astigmatism.
authors.affiliation: Department of Ophthalmology, Bristol Eye Hospital, England.
authors.forename: C H
authors.initials: CH
authors.lastname: Karabatsas
authors.forename: S D
authors.initials: SD
authors.lastname: Cook
authors.forename: F C
authors.initials: FC
authors.lastname: Figueiredo
authors.forename: J P
authors.initials: JP
authors.lastname: Diamond
authors.forename: D L
authors.initials: DL
authors.lastname: Easty
mesh_terms: D000293:Adolescent; D000328:Adult; D001251:Astigmatism / Q000209:etiology / Q000601:surgery*; D003315:Cornea / Q000601:surgery*; D019781:Corneal Topography / Q000379:methods*; D006801:Humans; D015948:Keratoplasty, Penetrating / Q000009:adverse effects*; D007646:Keratotomy, Radial; D011183:Postoperative Complications / Q000601:surgery*; D011446:Prospective Studies; D012029:Refraction, Ocular; D013536:Suture Techniques; D014792:Visual Acuity