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

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.

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).

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).

In addition to its optical advantages, nonmechanical corneal trephination appears to have no adverse impact on cataract formation after PKP for keratoconus.