Abstract
Purpose :
To determine the posterior optic edge profile of Akreos intraocular lenses (Bausch & Lomb) that have been tumble polished using a “mask” to protect the posterior optic square edge.
Methods :
Akreos IOLs are diamond turned lathed products, designed and machined to have a 360° posterior optic barrier edge with an intended posterior optic edge radius measuring less than 10µm. To maintain the “as machined” square posterior optic edge, a two part mask molded from polypropylene material was developed and used to encapsulate the product and protect the posterior optic edge from contact with polish beads during the tumble polish process, hence maintaining the posterior optic edge feature as it was created during the lathing process.
After machining and before polishing, the posterior optic edge radius was measured with the lens in the pre-hydrated state. Measurements were made at two locations, on the optic body edge and on the optic/haptic edge. These measurements were made in air using a Keyence model VK-8710 confocal microscope at a calibrated magnification of approximately 1000x. Lenses were then polished using the normal Akreos polish process but with each lens contained in a “mask”. After the lens was hydrated and polished, lenses were cross-sectioned and the posterior optic edge radius was measured. Measurements were made using a Keyence model VW-6000 at a calibrated 1000x magnification. The edge radius measurements were calculated using Keyence analysis tools for a three point fit to the edge section profile. Pre hydrated data provided the basis from which the lathed edge was verified to be as designed, below 10µm. Sectioned hydrated lens data showed the final posterior optic radius for the finished product.
Results :
Test samples of Akreos intraocular lenses that were polished using a “mask” were found to have an average posterior optic edge radius of 5µm with an observed range of 4µm, with no measurements exceeding 9µm in radius. This compared closely to the before polished, as machined, posterior optic edge radius.
Conclusions :
The posterior optic edge of Akreos intraocular lenses is maintained to be less than 10µm when the lens is polished using a protective “mask” process.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.