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

Purpose: To compare the lens opacity formation after penetrating keratoplas ty (PKP) using nonmechanical excimer laser corneal trephination and mechani cal motor trephination. Setting: University Eye Clinic, University of Erlangen-Nurnberg, Erlangen, Germany. Methods: Ninety-six patients with keratoconus (96 eyes) and clear crystalli ne lenses were randomly assigned to the nonmechanical trephination (NMT) gr oup (n = 46; 35 men; mean age 38.2 years +/- 10.8 [SD]) or the mechanical t rephination (MT) group (n = 50; 35 men; mean age 34.4 +/- 9.0 years). Sutur ing and postoperative treatment were identical. Dilated pupil biomicroscopy and slitlamp lens photography were performed preoperatively and postoperat ively 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% o f eyes. One patient in each group presented grade 3 posterior subcapsular o pacities. 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). Conclusion: In addition to its optical advantages, nonmechanical corneal tr ephination appears to have no adverse impact on cataract formation after PK P for keratoconus. J Cataract Refract Surg 2000; 26: 1605-1611 (C) 2000 ASC RS and ESCRS.