Choyce lens warp testing: effect of temperature and pressure changes

Choyce-style lenses made from sheer PMMA (ICI Perspex CQ) have a different thermal response than lenses made of Rohm & Haas injection molded PMMA: Perspex lenses are more resistant to high temperature deformation. However, under simulated physiologic temperatures and pressures, there is no apparent lens deformation, nor is there a difference in response between lens types. In general, the susceptibility of all thermoplastics to heat, and the ease with which high temperatures may be achieved in transportation, require improved packaging; great care must be taken to protect and inspect intraocular lenses before implantation. Demonstrated variation in thermal response from lens to lens, and even from foot to foot, further mandates such care and also cautions against the acceptance of claims based on inadequate or incomplete data. All lenses should be checked, with the best clinical test for flatness being that in which each foot is depressed to check for rocking or lift.