Effect of therapeutic ultrasound on intraocular lenses

High intensity, focused ultrasound energy is currently being evaluated as a therapy for glaucoma. The energy is delivered through conjunctiva and sclera to the pars plicata. The haptics of intraocular lenses may erode into the pars plicata, and we were therefore prompted to study the effects of ultrasound energy on intraocular lenses. The energy is highly absorbed by polymethylmethacrylate (PMMA), resulting in partial melting, vacuolization, and opacification of this material at intensities much lower than those used in the glaucoma treatment. Polypropylene absorbed much less of the energy, resulting in relatively minor morphologic changes with this material. We recommend caution in using this device in eyes with anterior chamber intraocular lenses and eyes with posterior chamber intraocular lenses having PMMA haptics.