Lens opacities after nonmechanical versus mechanical corneal trephination for keratoplasty in keratoconus

Purpose: To compare the lens opacity formation after penetrating keratoplasty (PKP) using nonmechanical excimer laser corneal trephination and mechanical motor trephination. Setting: University Eye Clinic, University of Erlangen-Nunberg, Erlangen, Germany. Methods: Ninety-six patients with keratoconus (96 eyes) and clear crystalline lenses were randomiy 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 2risk of lens opacity formation (P = .763 cortical, P = .530 posterior subcapsular). Conclusion: In addition to its optical advantages, nonmechanical corneal trephination appears to have no adverse impact on cataract formation after PKP for keratoconus. (C) 2000 ASCRS and ESCRS.