title: Lens opacities after nonmechanical versus mechanical corneal trephination for keratoplasty in keratoconus.
abstract: OBJECTIVE
  To compare the lens opacity formation after penetrating keratoplasty (PKP) using nonmechanical excimer laser corneal trephination and mechanical motor trephination. SETTTING: University Eye Clinic, University of Erlangen-Nürnberg, Erlangen, Germany.
  
  
  METHODS
  Ninety-six patients with keratoconus (96 eyes) and clear crystalline lenses were randomly assigned to the nonmechanical trephination (NMT) group (n = 46; 35 men; mean age 38.2 years +/- 10.8 [SD]) or the mechanical trephination (MT) group (n = 50; 35 men; mean age 34.4 +/- 9.0 years). Suturing and postoperative treatment were identical. Dilated pupil biomicroscopy and slitlamp lens photography were performed preoperatively and postoperatively at 3 month intervals. Opacities were identified as cortical, nuclear, and posterior subcapsular and graded from 1 (mild) to 3 (severe).
  
  
  RESULTS
  Mean follow-up in the NMT/MT group was 3.2 +/- 1.3 years/3.4 +/- 1.1 years. Overall, incident opacities appeared in 23.9%/32.0% of eyes (4.3%/6.0% cortical; 19. 6%/26.0% posterior subcapsular; 0%/0% nuclear) (P =.833). All cortical opacities in both groups were grade 1; posterior subcapsular opacities were grade 1 in 66.6%/61.5% of eyes and grade 2 in 22.2%/30.8% of eyes. One patient in each group presented grade 3 posterior subcapsular opacities. No differences between trephination methods were seen in a 5 year Kaplan-Meier cumulative risk of lens opacity formation (P =.763 cortical, P =.530 posterior subcapsular).
  
  
  CONCLUSIONS
  In addition to its optical advantages, nonmechanical corneal trephination appears to have no adverse impact on cataract formation after PKP for keratoconus.
authors.affiliation: Department of Ophthalmology, University of Erlangen-Nürnberg, Erlangen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Behrens
authors.forename: B
authors.initials: B
authors.lastname: Seitz
authors.forename: A
authors.initials: A
authors.lastname: Langenbucher
authors.forename: M M
authors.initials: MM
authors.lastname: Kus
authors.forename: M
authors.initials: M
authors.lastname: Küchle
authors.forename: G O
authors.initials: GO
authors.lastname: Naumann
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002386:Cataract / Q000209:etiology*; D003315:Cornea / Q000601:surgery*; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000601:surgery*; D015948:Keratoplasty, Penetrating / Q000009:adverse effects* / Q000379:methods; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors