POSTERIOR CAPSULE POLISHING WITH THE NEODYMIUM-YLF PICOSECOND LASER -MODEL EYE STUDY

Purpose: To determine the ability and threshold energy of the neodymiu m:yttriumlithium-fluoride (Nd:YLF) picosecond laser to achieve micron- level polishing of a latex posterior capsule facsimile (PCF) as an alt ernative to laser capsulotomy to treat posterior capsule opacification . Setting: University of Rochester Medical Center, Rochester, New York , USA. Methods: A solid-state, mode-locked Nd:YLF picosecond laser was used to polish a latex PCF in contact with a poly(methyl methacrylate ) intraocular lens (IOL) in an experimental model eye. Eight study gro ups were treated at different energy levels ranging from 5 to 15 mu J. All treatments were done at least three times in different latex caps ules and lenses. An atomic force microscope was used to measure IOL da mage and an interferometric surface analysis microscope to assess the polishing effect on the PCF. The IOLs were further subjected to a scat ter analysis to assess the optical significance of the damage produced .Results: The latex PCF revealed a polishing effect with all energy se ttings used. The IOLs were damaged with all energy settings but 5 mu J . Energy settings higher than 5 mu J caused significantly more polishi ng effect to the latex and damage to the lenses. At the 10 mu J energy level, a single parameter with no depth produced a relative polishing depth of 3.01 mu m +/- 0.10 (root mean square +/- SD). At this energy , the damage to the IOLs was 188 +/- 20.52 nm, and it was associated w ith typical craters over the surface at regular intervals that corresp onded to each individual laser pulse. Conclusion: This model documente d the feasibility of achieving micron-level precision in excising mate rial with the picosecond laser and showed that posterior capsule polis hing should be feasible and safe in human eyes.