EFFECTS OF THE PICOSECOND NEODYMIUM-YLF LASER ON POLY(METHYL METHACRYLATE) INTRAOCULAR LENSES DURING EXPERIMENTAL POSTERIOR CAPSULOTOMY

We evaluated the effect of the neodymium:YLF picosecond laser on intraocular lenses (IOLs) during experimental posterior capsulotomy and established the minimum damage threshold for lathe-cut poly(methyl methacrylate) (PMMA) IOLs. Single-piece, biconvex, lathe-cut PMMA lenses were placed in a model eye chamber against a latex membrane with a central area of lens-capsule touch. Energy levels from 40 mu J to 360 mu J pulse (0.4 mJ to 3.6 mJ) with a 0.5 mm line and a spot pattern were tested using different focal offsets. Threshold damage level was determined under the scanning electron microscope after observing the minimal energy level that did not cause damage to or pits in the IOLs. Lenses were then analyzed for size and type of damage. The 0.5 mm line pattern at 160 mu J using 350 mu m offset was safe and effective for posterior capsulotomy in vitro. The spot pattern caused IOL damage in the form of small pits at much lower energy levels of 80 mu J using 400 mu m offset than the line pattern.