RESUMO
PURPOSE: To develop a cadaver eye model that would assess posterior capsule (PC) vulnerability when different cataract removal technologies were evaluated and use the model to evaluate the relative amplitude levels required to rupture the human PC with the AquaLase handpiece (Alcon) compared with an ultrasound (US) handpiece. SETTING: Private practice, Cincinnati, Ohio, USA. METHODS: In part 1 of the study, 26 phakic human cadaver eyes were sectioned in the anteroposterior meridian. The anterior portion of the globe was placed cornea side down, and the vitreous was gently cleared from the posterior surface of the lens capsule. Ultrasound was applied directly to the central capsule after achieving a vacuum of 100 mm Hg. The power was incremented until rupture was observed. In part 2 of the study, the same procedure was repeated with 50 eye pairs. For each pair, US was randomly applied to 1 eye and AquaLase to the other. The 50 pairs were divided into 3 groups based on vacuum level: 100, 300, or 500 mm Hg. RESULTS: Part 1 results show that at 100 mm Hg, the mean power needed to break the PC with US was 19% +/- 6% (SD). There was no correlation between time from harvest to test and rupture power (R(2) = 0.04) or between donor age and rupture power (R(2) = 0.2). When the same procedure was repeated in part 2, on average, US power ruptured the capsule at a lower power than the AquaLase magnitude at each vacuum setting. The respective means were 18.5% +/- 6.7% and 61.0% +/- 23.3% for 100 mm Hg, 15.2% +/- 5.4% and 47.1% +/- 14.5% for 300 mm Hg, and 11.8% +/- 6.5% and 20.0% +/- 9.4% for 500 mm Hg. The difference between the groups and the values within each group decreased as vacuum levels increased. CONCLUSION: This new experimental model in a cadaver eye provides a useful method for comparing factors and techniques that contribute to PC rupture.